Hello,
syzbot found the following crash on:
HEAD commit: c10a026b kmsan: use __free_pages() in kmsan_iounmap_page_r..
git tree: kmsan
console output: https://syzkaller.appspot.com/x/log.txt?x=107d3c7d200000
kernel config: https://syzkaller.appspot.com/x/.config?x=a5675814e8eae69e
dashboard link: https://syzkaller.appspot.com/bug?extid=86b5c7c236a22616a72f
compiler: clang version 8.0.0 (trunk 350509)
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=1252834d200000
IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: [email protected]
IPv6: ADDRCONF(NETDEV_CHANGE): veth1_to_hsr: link becomes ready
IPv6: ADDRCONF(NETDEV_CHANGE): hsr_slave_1: link becomes ready
8021q: adding VLAN 0 to HW filter on device batadv0
8021q: adding VLAN 0 to HW filter on device batadv0
==================================================================
BUG: KMSAN: kernel-infoleak in _copy_to_user+0x16b/0x1f0 lib/usercopy.c:32
CPU: 0 PID: 10131 Comm: syz-executor.4 Not tainted 5.0.0+ #16
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
Google 01/01/2011
Call Trace:
__dump_stack lib/dump_stack.c:77 [inline]
dump_stack+0x173/0x1d0 lib/dump_stack.c:113
kmsan_report+0x131/0x2a0 mm/kmsan/kmsan.c:636
kmsan_internal_check_memory+0xaa1/0xbb0 mm/kmsan/kmsan.c:730
kmsan_copy_to_user+0xab/0xc0 mm/kmsan/kmsan_hooks.c:485
_copy_to_user+0x16b/0x1f0 lib/usercopy.c:32
copy_to_user include/linux/uaccess.h:174 [inline]
sctp_getsockopt_peer_addrs net/sctp/socket.c:5911 [inline]
sctp_getsockopt+0x1668e/0x17f70 net/sctp/socket.c:7562
sock_common_getsockopt+0x13f/0x180 net/core/sock.c:2950
__sys_getsockopt+0x489/0x550 net/socket.c:1938
__do_sys_getsockopt net/socket.c:1949 [inline]
__se_sys_getsockopt+0xe1/0x100 net/socket.c:1946
__x64_sys_getsockopt+0x62/0x80 net/socket.c:1946
do_syscall_64+0xbc/0xf0 arch/x86/entry/common.c:291
entry_SYSCALL_64_after_hwframe+0x63/0xe7
RIP: 0033:0x458209
Code: ad b8 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 48 89 f8 48 89 f7
48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff
ff 0f 83 7b b8 fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007fdbef191c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000037
RAX: ffffffffffffffda RBX: 0000000000000005 RCX: 0000000000458209
RDX: 000000000000006c RSI: 0000000000000084 RDI: 0000000000000004
RBP: 000000000073bf00 R08: 0000000020000300 R09: 0000000000000000
R10: 0000000020000280 R11: 0000000000000246 R12: 00007fdbef1926d4
R13: 00000000004c96c8 R14: 00000000004d0310 R15: 00000000ffffffff
Uninit was stored to memory at:
kmsan_save_stack_with_flags mm/kmsan/kmsan.c:205 [inline]
kmsan_save_stack mm/kmsan/kmsan.c:220 [inline]
kmsan_internal_chain_origin+0x134/0x230 mm/kmsan/kmsan.c:426
kmsan_memcpy_memmove_metadata+0xb5b/0xfe0 mm/kmsan/kmsan.c:304
kmsan_memcpy_metadata+0xb/0x10 mm/kmsan/kmsan.c:324
__msan_memcpy+0x58/0x70 mm/kmsan/kmsan_instr.c:139
sctp_getsockopt_peer_addrs net/sctp/socket.c:5906 [inline]
sctp_getsockopt+0x16556/0x17f70 net/sctp/socket.c:7562
sock_common_getsockopt+0x13f/0x180 net/core/sock.c:2950
__sys_getsockopt+0x489/0x550 net/socket.c:1938
__do_sys_getsockopt net/socket.c:1949 [inline]
__se_sys_getsockopt+0xe1/0x100 net/socket.c:1946
__x64_sys_getsockopt+0x62/0x80 net/socket.c:1946
do_syscall_64+0xbc/0xf0 arch/x86/entry/common.c:291
entry_SYSCALL_64_after_hwframe+0x63/0xe7
Uninit was stored to memory at:
kmsan_save_stack_with_flags mm/kmsan/kmsan.c:205 [inline]
kmsan_save_stack mm/kmsan/kmsan.c:220 [inline]
kmsan_internal_chain_origin+0x134/0x230 mm/kmsan/kmsan.c:426
kmsan_memcpy_memmove_metadata+0xb5b/0xfe0 mm/kmsan/kmsan.c:304
kmsan_memcpy_metadata+0xb/0x10 mm/kmsan/kmsan.c:324
__msan_memcpy+0x58/0x70 mm/kmsan/kmsan_instr.c:139
sctp_transport_init net/sctp/transport.c:61 [inline]
sctp_transport_new+0x16d/0x9a0 net/sctp/transport.c:115
sctp_assoc_add_peer+0x532/0x1f70 net/sctp/associola.c:637
sctp_process_param net/sctp/sm_make_chunk.c:2548 [inline]
sctp_process_init+0x1a1b/0x3ed0 net/sctp/sm_make_chunk.c:2361
sctp_cmd_process_init net/sctp/sm_sideeffect.c:682 [inline]
sctp_cmd_interpreter net/sctp/sm_sideeffect.c:1410 [inline]
sctp_side_effects net/sctp/sm_sideeffect.c:1220 [inline]
sctp_do_sm+0x3cfc/0x9af0 net/sctp/sm_sideeffect.c:1191
sctp_assoc_bh_rcv+0x65a/0xd80 net/sctp/associola.c:1074
sctp_inq_push+0x300/0x420 net/sctp/inqueue.c:95
sctp_backlog_rcv+0x20a/0xaf0 net/sctp/input.c:354
sk_backlog_rcv include/net/sock.h:936 [inline]
__release_sock+0x281/0x5f0 net/core/sock.c:2284
release_sock+0x99/0x2a0 net/core/sock.c:2800
sctp_wait_for_connect+0x3ee/0x860 net/sctp/socket.c:8751
sctp_sendmsg_to_asoc+0x2167/0x21a0 net/sctp/socket.c:1967
sctp_sendmsg+0x3fd7/0x6700 net/sctp/socket.c:2113
inet_sendmsg+0x54a/0x720 net/ipv4/af_inet.c:798
sock_sendmsg_nosec net/socket.c:622 [inline]
sock_sendmsg net/socket.c:632 [inline]
___sys_sendmsg+0xdb9/0x11b0 net/socket.c:2115
__sys_sendmsg net/socket.c:2153 [inline]
__do_sys_sendmsg net/socket.c:2162 [inline]
__se_sys_sendmsg+0x305/0x460 net/socket.c:2160
__x64_sys_sendmsg+0x4a/0x70 net/socket.c:2160
do_syscall_64+0xbc/0xf0 arch/x86/entry/common.c:291
entry_SYSCALL_64_after_hwframe+0x63/0xe7
Local variable description: ----addr.i@sctp_process_init
Variable was created at:
sctp_process_init+0xb5/0x3ed0 net/sctp/sm_make_chunk.c:2324
sctp_cmd_process_init net/sctp/sm_sideeffect.c:682 [inline]
sctp_cmd_interpreter net/sctp/sm_sideeffect.c:1410 [inline]
sctp_side_effects net/sctp/sm_sideeffect.c:1220 [inline]
sctp_do_sm+0x3cfc/0x9af0 net/sctp/sm_sideeffect.c:1191
Bytes 8-15 of 16 are uninitialized
Memory access of size 16 starts at ffff88809511fc28
Data copied to user address 0000000020000298
==================================================================
---
This bug is generated by a bot. It may contain errors.
See https://goo.gl/tpsmEJ for more information about syzbot.
syzbot engineers can be reached at [email protected].
syzbot will keep track of this bug report. See:
https://goo.gl/tpsmEJ#status for how to communicate with syzbot.
syzbot can test patches for this bug, for details see:
https://goo.gl/tpsmEJ#testing-patches
On Thu, Mar 28, 2019 at 09:25:06AM -0700, syzbot wrote:
> Hello,
>
> syzbot found the following crash on:
>
> HEAD commit: c10a026b kmsan: use __free_pages() in kmsan_iounmap_page_r..
> git tree: kmsan
> console output: https://syzkaller.appspot.com/x/log.txt?x=107d3c7d200000
> kernel config: https://syzkaller.appspot.com/x/.config?x=a5675814e8eae69e
> dashboard link: https://syzkaller.appspot.com/bug?extid=86b5c7c236a22616a72f
> compiler: clang version 8.0.0 (trunk 350509)
> syz repro: https://syzkaller.appspot.com/x/repro.syz?x=1252834d200000
>
> IMPORTANT: if you fix the bug, please add the following tag to the commit:
> Reported-by: [email protected]
>
> IPv6: ADDRCONF(NETDEV_CHANGE): veth1_to_hsr: link becomes ready
> IPv6: ADDRCONF(NETDEV_CHANGE): hsr_slave_1: link becomes ready
> 8021q: adding VLAN 0 to HW filter on device batadv0
> 8021q: adding VLAN 0 to HW filter on device batadv0
> ==================================================================
> BUG: KMSAN: kernel-infoleak in _copy_to_user+0x16b/0x1f0 lib/usercopy.c:32
> CPU: 0 PID: 10131 Comm: syz-executor.4 Not tainted 5.0.0+ #16
> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
> Google 01/01/2011
> Call Trace:
> __dump_stack lib/dump_stack.c:77 [inline]
> dump_stack+0x173/0x1d0 lib/dump_stack.c:113
> kmsan_report+0x131/0x2a0 mm/kmsan/kmsan.c:636
> kmsan_internal_check_memory+0xaa1/0xbb0 mm/kmsan/kmsan.c:730
> kmsan_copy_to_user+0xab/0xc0 mm/kmsan/kmsan_hooks.c:485
> _copy_to_user+0x16b/0x1f0 lib/usercopy.c:32
> copy_to_user include/linux/uaccess.h:174 [inline]
> sctp_getsockopt_peer_addrs net/sctp/socket.c:5911 [inline]
> sctp_getsockopt+0x1668e/0x17f70 net/sctp/socket.c:7562
> sock_common_getsockopt+0x13f/0x180 net/core/sock.c:2950
> __sys_getsockopt+0x489/0x550 net/socket.c:1938
> __do_sys_getsockopt net/socket.c:1949 [inline]
> __se_sys_getsockopt+0xe1/0x100 net/socket.c:1946
> __x64_sys_getsockopt+0x62/0x80 net/socket.c:1946
> do_syscall_64+0xbc/0xf0 arch/x86/entry/common.c:291
> entry_SYSCALL_64_after_hwframe+0x63/0xe7
> RIP: 0033:0x458209
> Code: ad b8 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 48 89 f8 48 89 f7
> 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff
> 0f 83 7b b8 fb ff c3 66 2e 0f 1f 84 00 00 00 00
> RSP: 002b:00007fdbef191c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000037
> RAX: ffffffffffffffda RBX: 0000000000000005 RCX: 0000000000458209
> RDX: 000000000000006c RSI: 0000000000000084 RDI: 0000000000000004
> RBP: 000000000073bf00 R08: 0000000020000300 R09: 0000000000000000
> R10: 0000000020000280 R11: 0000000000000246 R12: 00007fdbef1926d4
> R13: 00000000004c96c8 R14: 00000000004d0310 R15: 00000000ffffffff
>
> Uninit was stored to memory at:
> kmsan_save_stack_with_flags mm/kmsan/kmsan.c:205 [inline]
> kmsan_save_stack mm/kmsan/kmsan.c:220 [inline]
> kmsan_internal_chain_origin+0x134/0x230 mm/kmsan/kmsan.c:426
> kmsan_memcpy_memmove_metadata+0xb5b/0xfe0 mm/kmsan/kmsan.c:304
> kmsan_memcpy_metadata+0xb/0x10 mm/kmsan/kmsan.c:324
> __msan_memcpy+0x58/0x70 mm/kmsan/kmsan_instr.c:139
> sctp_getsockopt_peer_addrs net/sctp/socket.c:5906 [inline]
> sctp_getsockopt+0x16556/0x17f70 net/sctp/socket.c:7562
> sock_common_getsockopt+0x13f/0x180 net/core/sock.c:2950
> __sys_getsockopt+0x489/0x550 net/socket.c:1938
> __do_sys_getsockopt net/socket.c:1949 [inline]
> __se_sys_getsockopt+0xe1/0x100 net/socket.c:1946
> __x64_sys_getsockopt+0x62/0x80 net/socket.c:1946
> do_syscall_64+0xbc/0xf0 arch/x86/entry/common.c:291
> entry_SYSCALL_64_after_hwframe+0x63/0xe7
>
> Uninit was stored to memory at:
> kmsan_save_stack_with_flags mm/kmsan/kmsan.c:205 [inline]
> kmsan_save_stack mm/kmsan/kmsan.c:220 [inline]
> kmsan_internal_chain_origin+0x134/0x230 mm/kmsan/kmsan.c:426
> kmsan_memcpy_memmove_metadata+0xb5b/0xfe0 mm/kmsan/kmsan.c:304
> kmsan_memcpy_metadata+0xb/0x10 mm/kmsan/kmsan.c:324
> __msan_memcpy+0x58/0x70 mm/kmsan/kmsan_instr.c:139
> sctp_transport_init net/sctp/transport.c:61 [inline]
> sctp_transport_new+0x16d/0x9a0 net/sctp/transport.c:115
> sctp_assoc_add_peer+0x532/0x1f70 net/sctp/associola.c:637
> sctp_process_param net/sctp/sm_make_chunk.c:2548 [inline]
> sctp_process_init+0x1a1b/0x3ed0 net/sctp/sm_make_chunk.c:2361
> sctp_cmd_process_init net/sctp/sm_sideeffect.c:682 [inline]
> sctp_cmd_interpreter net/sctp/sm_sideeffect.c:1410 [inline]
> sctp_side_effects net/sctp/sm_sideeffect.c:1220 [inline]
> sctp_do_sm+0x3cfc/0x9af0 net/sctp/sm_sideeffect.c:1191
> sctp_assoc_bh_rcv+0x65a/0xd80 net/sctp/associola.c:1074
> sctp_inq_push+0x300/0x420 net/sctp/inqueue.c:95
> sctp_backlog_rcv+0x20a/0xaf0 net/sctp/input.c:354
> sk_backlog_rcv include/net/sock.h:936 [inline]
> __release_sock+0x281/0x5f0 net/core/sock.c:2284
> release_sock+0x99/0x2a0 net/core/sock.c:2800
> sctp_wait_for_connect+0x3ee/0x860 net/sctp/socket.c:8751
> sctp_sendmsg_to_asoc+0x2167/0x21a0 net/sctp/socket.c:1967
> sctp_sendmsg+0x3fd7/0x6700 net/sctp/socket.c:2113
> inet_sendmsg+0x54a/0x720 net/ipv4/af_inet.c:798
> sock_sendmsg_nosec net/socket.c:622 [inline]
> sock_sendmsg net/socket.c:632 [inline]
> ___sys_sendmsg+0xdb9/0x11b0 net/socket.c:2115
> __sys_sendmsg net/socket.c:2153 [inline]
> __do_sys_sendmsg net/socket.c:2162 [inline]
> __se_sys_sendmsg+0x305/0x460 net/socket.c:2160
> __x64_sys_sendmsg+0x4a/0x70 net/socket.c:2160
> do_syscall_64+0xbc/0xf0 arch/x86/entry/common.c:291
> entry_SYSCALL_64_after_hwframe+0x63/0xe7
>
> Local variable description: ----addr.i@sctp_process_init
> Variable was created at:
> sctp_process_init+0xb5/0x3ed0 net/sctp/sm_make_chunk.c:2324
> sctp_cmd_process_init net/sctp/sm_sideeffect.c:682 [inline]
> sctp_cmd_interpreter net/sctp/sm_sideeffect.c:1410 [inline]
> sctp_side_effects net/sctp/sm_sideeffect.c:1220 [inline]
> sctp_do_sm+0x3cfc/0x9af0 net/sctp/sm_sideeffect.c:1191
>
> Bytes 8-15 of 16 are uninitialized
> Memory access of size 16 starts at ffff88809511fc28
> Data copied to user address 0000000020000298
> ==================================================================
>
>
> ---
> This bug is generated by a bot. It may contain errors.
> See https://goo.gl/tpsmEJ for more information about syzbot.
> syzbot engineers can be reached at [email protected].
>
> syzbot will keep track of this bug report. See:
> https://goo.gl/tpsmEJ#status for how to communicate with syzbot.
> syzbot can test patches for this bug, for details see:
> https://goo.gl/tpsmEJ#testing-patches
>
>
Hmm, odd. I see where we are doing the copy_to_user call in
getsockopt_peer_addrs, but the length we copy should always be equal to or less
than what was memcopied to the temp variable. False positive?
Neil
On Fri, Mar 29, 2019 at 3:51 PM Neil Horman <[email protected]> wrote:
>
> On Thu, Mar 28, 2019 at 09:25:06AM -0700, syzbot wrote:
> > Hello,
> >
> > syzbot found the following crash on:
> >
> > HEAD commit: c10a026b kmsan: use __free_pages() in kmsan_iounmap_page_r..
> > git tree: kmsan
> > console output: https://syzkaller.appspot.com/x/log.txt?x=107d3c7d200000
> > kernel config: https://syzkaller.appspot.com/x/.config?x=a5675814e8eae69e
> > dashboard link: https://syzkaller.appspot.com/bug?extid=86b5c7c236a22616a72f
> > compiler: clang version 8.0.0 (trunk 350509)
> > syz repro: https://syzkaller.appspot.com/x/repro.syz?x=1252834d200000
> >
> > IMPORTANT: if you fix the bug, please add the following tag to the commit:
> > Reported-by: [email protected]
> >
> > IPv6: ADDRCONF(NETDEV_CHANGE): veth1_to_hsr: link becomes ready
> > IPv6: ADDRCONF(NETDEV_CHANGE): hsr_slave_1: link becomes ready
> > 8021q: adding VLAN 0 to HW filter on device batadv0
> > 8021q: adding VLAN 0 to HW filter on device batadv0
> > ==================================================================
> > BUG: KMSAN: kernel-infoleak in _copy_to_user+0x16b/0x1f0 lib/usercopy.c:32
> > CPU: 0 PID: 10131 Comm: syz-executor.4 Not tainted 5.0.0+ #16
> > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
> > Google 01/01/2011
> > Call Trace:
> > __dump_stack lib/dump_stack.c:77 [inline]
> > dump_stack+0x173/0x1d0 lib/dump_stack.c:113
> > kmsan_report+0x131/0x2a0 mm/kmsan/kmsan.c:636
> > kmsan_internal_check_memory+0xaa1/0xbb0 mm/kmsan/kmsan.c:730
> > kmsan_copy_to_user+0xab/0xc0 mm/kmsan/kmsan_hooks.c:485
> > _copy_to_user+0x16b/0x1f0 lib/usercopy.c:32
> > copy_to_user include/linux/uaccess.h:174 [inline]
> > sctp_getsockopt_peer_addrs net/sctp/socket.c:5911 [inline]
> > sctp_getsockopt+0x1668e/0x17f70 net/sctp/socket.c:7562
> > sock_common_getsockopt+0x13f/0x180 net/core/sock.c:2950
> > __sys_getsockopt+0x489/0x550 net/socket.c:1938
> > __do_sys_getsockopt net/socket.c:1949 [inline]
> > __se_sys_getsockopt+0xe1/0x100 net/socket.c:1946
> > __x64_sys_getsockopt+0x62/0x80 net/socket.c:1946
> > do_syscall_64+0xbc/0xf0 arch/x86/entry/common.c:291
> > entry_SYSCALL_64_after_hwframe+0x63/0xe7
> > RIP: 0033:0x458209
> > Code: ad b8 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 48 89 f8 48 89 f7
> > 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff
> > 0f 83 7b b8 fb ff c3 66 2e 0f 1f 84 00 00 00 00
> > RSP: 002b:00007fdbef191c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000037
> > RAX: ffffffffffffffda RBX: 0000000000000005 RCX: 0000000000458209
> > RDX: 000000000000006c RSI: 0000000000000084 RDI: 0000000000000004
> > RBP: 000000000073bf00 R08: 0000000020000300 R09: 0000000000000000
> > R10: 0000000020000280 R11: 0000000000000246 R12: 00007fdbef1926d4
> > R13: 00000000004c96c8 R14: 00000000004d0310 R15: 00000000ffffffff
> >
> > Uninit was stored to memory at:
> > kmsan_save_stack_with_flags mm/kmsan/kmsan.c:205 [inline]
> > kmsan_save_stack mm/kmsan/kmsan.c:220 [inline]
> > kmsan_internal_chain_origin+0x134/0x230 mm/kmsan/kmsan.c:426
> > kmsan_memcpy_memmove_metadata+0xb5b/0xfe0 mm/kmsan/kmsan.c:304
> > kmsan_memcpy_metadata+0xb/0x10 mm/kmsan/kmsan.c:324
> > __msan_memcpy+0x58/0x70 mm/kmsan/kmsan_instr.c:139
> > sctp_getsockopt_peer_addrs net/sctp/socket.c:5906 [inline]
> > sctp_getsockopt+0x16556/0x17f70 net/sctp/socket.c:7562
> > sock_common_getsockopt+0x13f/0x180 net/core/sock.c:2950
> > __sys_getsockopt+0x489/0x550 net/socket.c:1938
> > __do_sys_getsockopt net/socket.c:1949 [inline]
> > __se_sys_getsockopt+0xe1/0x100 net/socket.c:1946
> > __x64_sys_getsockopt+0x62/0x80 net/socket.c:1946
> > do_syscall_64+0xbc/0xf0 arch/x86/entry/common.c:291
> > entry_SYSCALL_64_after_hwframe+0x63/0xe7
> >
> > Uninit was stored to memory at:
> > kmsan_save_stack_with_flags mm/kmsan/kmsan.c:205 [inline]
> > kmsan_save_stack mm/kmsan/kmsan.c:220 [inline]
> > kmsan_internal_chain_origin+0x134/0x230 mm/kmsan/kmsan.c:426
> > kmsan_memcpy_memmove_metadata+0xb5b/0xfe0 mm/kmsan/kmsan.c:304
> > kmsan_memcpy_metadata+0xb/0x10 mm/kmsan/kmsan.c:324
> > __msan_memcpy+0x58/0x70 mm/kmsan/kmsan_instr.c:139
> > sctp_transport_init net/sctp/transport.c:61 [inline]
> > sctp_transport_new+0x16d/0x9a0 net/sctp/transport.c:115
> > sctp_assoc_add_peer+0x532/0x1f70 net/sctp/associola.c:637
> > sctp_process_param net/sctp/sm_make_chunk.c:2548 [inline]
> > sctp_process_init+0x1a1b/0x3ed0 net/sctp/sm_make_chunk.c:2361
> > sctp_cmd_process_init net/sctp/sm_sideeffect.c:682 [inline]
> > sctp_cmd_interpreter net/sctp/sm_sideeffect.c:1410 [inline]
> > sctp_side_effects net/sctp/sm_sideeffect.c:1220 [inline]
> > sctp_do_sm+0x3cfc/0x9af0 net/sctp/sm_sideeffect.c:1191
> > sctp_assoc_bh_rcv+0x65a/0xd80 net/sctp/associola.c:1074
> > sctp_inq_push+0x300/0x420 net/sctp/inqueue.c:95
> > sctp_backlog_rcv+0x20a/0xaf0 net/sctp/input.c:354
> > sk_backlog_rcv include/net/sock.h:936 [inline]
> > __release_sock+0x281/0x5f0 net/core/sock.c:2284
> > release_sock+0x99/0x2a0 net/core/sock.c:2800
> > sctp_wait_for_connect+0x3ee/0x860 net/sctp/socket.c:8751
> > sctp_sendmsg_to_asoc+0x2167/0x21a0 net/sctp/socket.c:1967
> > sctp_sendmsg+0x3fd7/0x6700 net/sctp/socket.c:2113
> > inet_sendmsg+0x54a/0x720 net/ipv4/af_inet.c:798
> > sock_sendmsg_nosec net/socket.c:622 [inline]
> > sock_sendmsg net/socket.c:632 [inline]
> > ___sys_sendmsg+0xdb9/0x11b0 net/socket.c:2115
> > __sys_sendmsg net/socket.c:2153 [inline]
> > __do_sys_sendmsg net/socket.c:2162 [inline]
> > __se_sys_sendmsg+0x305/0x460 net/socket.c:2160
> > __x64_sys_sendmsg+0x4a/0x70 net/socket.c:2160
> > do_syscall_64+0xbc/0xf0 arch/x86/entry/common.c:291
> > entry_SYSCALL_64_after_hwframe+0x63/0xe7
> >
> > Local variable description: ----addr.i@sctp_process_init
> > Variable was created at:
> > sctp_process_init+0xb5/0x3ed0 net/sctp/sm_make_chunk.c:2324
> > sctp_cmd_process_init net/sctp/sm_sideeffect.c:682 [inline]
> > sctp_cmd_interpreter net/sctp/sm_sideeffect.c:1410 [inline]
> > sctp_side_effects net/sctp/sm_sideeffect.c:1220 [inline]
> > sctp_do_sm+0x3cfc/0x9af0 net/sctp/sm_sideeffect.c:1191
> >
> > Bytes 8-15 of 16 are uninitialized
> > Memory access of size 16 starts at ffff88809511fc28
> > Data copied to user address 0000000020000298
> > ==================================================================
> >
> >
> > ---
> > This bug is generated by a bot. It may contain errors.
> > See https://goo.gl/tpsmEJ for more information about syzbot.
> > syzbot engineers can be reached at [email protected].
> >
> > syzbot will keep track of this bug report. See:
> > https://goo.gl/tpsmEJ#status for how to communicate with syzbot.
> > syzbot can test patches for this bug, for details see:
> > https://goo.gl/tpsmEJ#testing-patches
> >
> >
>
>
> Hmm, odd. I see where we are doing the copy_to_user call in
> getsockopt_peer_addrs, but the length we copy should always be equal to or less
> than what was memcopied to the temp variable. False positive?
I'll take a closer look next week.
The bug is reproducible with the following syzkaller program:
r0 = socket$inet(0x2, 0x80001, 0x84)
bind$inet(r0, &(0x7f0000000080)={0x2, 0x4e20, @empty}, 0x10)
sendmsg(r0, &(0x7f0000000100)={&(0x7f0000006000)=@in={0x2, 0x4e20,
@loopback}, 0x80, &(0x7f0000007f80)=[{&(0x7f00000001c0)="de", 0x1}],
0x1}, 0x0)
getsockopt$inet_sctp_SCTP_GET_PEER_ADDRS(r0, 0x84, 0x6c,
&(0x7f0000000000)={<r5=>0x0, 0x38,
"41925f90e4121fadc9c1296dd22ae19d0b1b0942e46fc79e2ecec1056b23199f0ca008915d8dba1b3896c154f2244bbe859fe3423a4b437a"},
&(0x7f0000000040)=0x40)
Just need to check where the uninitializedness comes from.
> Neil
>
--
Alexander Potapenko
Software Engineer
Google Germany GmbH
Erika-Mann-Straße, 33
80636 München
Geschäftsführer: Paul Manicle, Halimah DeLaine Prado
Registergericht und -nummer: Hamburg, HRB 86891
Sitz der Gesellschaft: Hamburg
On Fri, Mar 29, 2019 at 06:35:40PM +0100, Alexander Potapenko wrote:
> On Fri, Mar 29, 2019 at 3:51 PM Neil Horman <[email protected]> wrote:
> >
> > On Thu, Mar 28, 2019 at 09:25:06AM -0700, syzbot wrote:
> > > Hello,
> > >
> > > syzbot found the following crash on:
> > >
> > > HEAD commit: c10a026b kmsan: use __free_pages() in kmsan_iounmap_page_r..
> > > git tree: kmsan
> > > console output: https://syzkaller.appspot.com/x/log.txt?x=107d3c7d200000
> > > kernel config: https://syzkaller.appspot.com/x/.config?x=a5675814e8eae69e
> > > dashboard link: https://syzkaller.appspot.com/bug?extid=86b5c7c236a22616a72f
> > > compiler: clang version 8.0.0 (trunk 350509)
> > > syz repro: https://syzkaller.appspot.com/x/repro.syz?x=1252834d200000
> > >
> > > IMPORTANT: if you fix the bug, please add the following tag to the commit:
> > > Reported-by: [email protected]
> > >
> > > IPv6: ADDRCONF(NETDEV_CHANGE): veth1_to_hsr: link becomes ready
> > > IPv6: ADDRCONF(NETDEV_CHANGE): hsr_slave_1: link becomes ready
> > > 8021q: adding VLAN 0 to HW filter on device batadv0
> > > 8021q: adding VLAN 0 to HW filter on device batadv0
> > > ==================================================================
> > > BUG: KMSAN: kernel-infoleak in _copy_to_user+0x16b/0x1f0 lib/usercopy.c:32
> > > CPU: 0 PID: 10131 Comm: syz-executor.4 Not tainted 5.0.0+ #16
> > > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
> > > Google 01/01/2011
> > > Call Trace:
> > > __dump_stack lib/dump_stack.c:77 [inline]
> > > dump_stack+0x173/0x1d0 lib/dump_stack.c:113
> > > kmsan_report+0x131/0x2a0 mm/kmsan/kmsan.c:636
> > > kmsan_internal_check_memory+0xaa1/0xbb0 mm/kmsan/kmsan.c:730
> > > kmsan_copy_to_user+0xab/0xc0 mm/kmsan/kmsan_hooks.c:485
> > > _copy_to_user+0x16b/0x1f0 lib/usercopy.c:32
> > > copy_to_user include/linux/uaccess.h:174 [inline]
> > > sctp_getsockopt_peer_addrs net/sctp/socket.c:5911 [inline]
> > > sctp_getsockopt+0x1668e/0x17f70 net/sctp/socket.c:7562
> > > sock_common_getsockopt+0x13f/0x180 net/core/sock.c:2950
> > > __sys_getsockopt+0x489/0x550 net/socket.c:1938
> > > __do_sys_getsockopt net/socket.c:1949 [inline]
> > > __se_sys_getsockopt+0xe1/0x100 net/socket.c:1946
> > > __x64_sys_getsockopt+0x62/0x80 net/socket.c:1946
> > > do_syscall_64+0xbc/0xf0 arch/x86/entry/common.c:291
> > > entry_SYSCALL_64_after_hwframe+0x63/0xe7
> > > RIP: 0033:0x458209
> > > Code: ad b8 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 48 89 f8 48 89 f7
> > > 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff
> > > 0f 83 7b b8 fb ff c3 66 2e 0f 1f 84 00 00 00 00
> > > RSP: 002b:00007fdbef191c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000037
> > > RAX: ffffffffffffffda RBX: 0000000000000005 RCX: 0000000000458209
> > > RDX: 000000000000006c RSI: 0000000000000084 RDI: 0000000000000004
> > > RBP: 000000000073bf00 R08: 0000000020000300 R09: 0000000000000000
> > > R10: 0000000020000280 R11: 0000000000000246 R12: 00007fdbef1926d4
> > > R13: 00000000004c96c8 R14: 00000000004d0310 R15: 00000000ffffffff
> > >
> > > Uninit was stored to memory at:
> > > kmsan_save_stack_with_flags mm/kmsan/kmsan.c:205 [inline]
> > > kmsan_save_stack mm/kmsan/kmsan.c:220 [inline]
> > > kmsan_internal_chain_origin+0x134/0x230 mm/kmsan/kmsan.c:426
> > > kmsan_memcpy_memmove_metadata+0xb5b/0xfe0 mm/kmsan/kmsan.c:304
> > > kmsan_memcpy_metadata+0xb/0x10 mm/kmsan/kmsan.c:324
> > > __msan_memcpy+0x58/0x70 mm/kmsan/kmsan_instr.c:139
> > > sctp_getsockopt_peer_addrs net/sctp/socket.c:5906 [inline]
> > > sctp_getsockopt+0x16556/0x17f70 net/sctp/socket.c:7562
> > > sock_common_getsockopt+0x13f/0x180 net/core/sock.c:2950
> > > __sys_getsockopt+0x489/0x550 net/socket.c:1938
> > > __do_sys_getsockopt net/socket.c:1949 [inline]
> > > __se_sys_getsockopt+0xe1/0x100 net/socket.c:1946
> > > __x64_sys_getsockopt+0x62/0x80 net/socket.c:1946
> > > do_syscall_64+0xbc/0xf0 arch/x86/entry/common.c:291
> > > entry_SYSCALL_64_after_hwframe+0x63/0xe7
> > >
> > > Uninit was stored to memory at:
> > > kmsan_save_stack_with_flags mm/kmsan/kmsan.c:205 [inline]
> > > kmsan_save_stack mm/kmsan/kmsan.c:220 [inline]
> > > kmsan_internal_chain_origin+0x134/0x230 mm/kmsan/kmsan.c:426
> > > kmsan_memcpy_memmove_metadata+0xb5b/0xfe0 mm/kmsan/kmsan.c:304
> > > kmsan_memcpy_metadata+0xb/0x10 mm/kmsan/kmsan.c:324
> > > __msan_memcpy+0x58/0x70 mm/kmsan/kmsan_instr.c:139
> > > sctp_transport_init net/sctp/transport.c:61 [inline]
> > > sctp_transport_new+0x16d/0x9a0 net/sctp/transport.c:115
> > > sctp_assoc_add_peer+0x532/0x1f70 net/sctp/associola.c:637
> > > sctp_process_param net/sctp/sm_make_chunk.c:2548 [inline]
> > > sctp_process_init+0x1a1b/0x3ed0 net/sctp/sm_make_chunk.c:2361
> > > sctp_cmd_process_init net/sctp/sm_sideeffect.c:682 [inline]
> > > sctp_cmd_interpreter net/sctp/sm_sideeffect.c:1410 [inline]
> > > sctp_side_effects net/sctp/sm_sideeffect.c:1220 [inline]
> > > sctp_do_sm+0x3cfc/0x9af0 net/sctp/sm_sideeffect.c:1191
> > > sctp_assoc_bh_rcv+0x65a/0xd80 net/sctp/associola.c:1074
> > > sctp_inq_push+0x300/0x420 net/sctp/inqueue.c:95
> > > sctp_backlog_rcv+0x20a/0xaf0 net/sctp/input.c:354
> > > sk_backlog_rcv include/net/sock.h:936 [inline]
> > > __release_sock+0x281/0x5f0 net/core/sock.c:2284
> > > release_sock+0x99/0x2a0 net/core/sock.c:2800
> > > sctp_wait_for_connect+0x3ee/0x860 net/sctp/socket.c:8751
> > > sctp_sendmsg_to_asoc+0x2167/0x21a0 net/sctp/socket.c:1967
> > > sctp_sendmsg+0x3fd7/0x6700 net/sctp/socket.c:2113
> > > inet_sendmsg+0x54a/0x720 net/ipv4/af_inet.c:798
> > > sock_sendmsg_nosec net/socket.c:622 [inline]
> > > sock_sendmsg net/socket.c:632 [inline]
> > > ___sys_sendmsg+0xdb9/0x11b0 net/socket.c:2115
> > > __sys_sendmsg net/socket.c:2153 [inline]
> > > __do_sys_sendmsg net/socket.c:2162 [inline]
> > > __se_sys_sendmsg+0x305/0x460 net/socket.c:2160
> > > __x64_sys_sendmsg+0x4a/0x70 net/socket.c:2160
> > > do_syscall_64+0xbc/0xf0 arch/x86/entry/common.c:291
> > > entry_SYSCALL_64_after_hwframe+0x63/0xe7
> > >
> > > Local variable description: ----addr.i@sctp_process_init
> > > Variable was created at:
> > > sctp_process_init+0xb5/0x3ed0 net/sctp/sm_make_chunk.c:2324
> > > sctp_cmd_process_init net/sctp/sm_sideeffect.c:682 [inline]
> > > sctp_cmd_interpreter net/sctp/sm_sideeffect.c:1410 [inline]
> > > sctp_side_effects net/sctp/sm_sideeffect.c:1220 [inline]
> > > sctp_do_sm+0x3cfc/0x9af0 net/sctp/sm_sideeffect.c:1191
> > >
> > > Bytes 8-15 of 16 are uninitialized
> > > Memory access of size 16 starts at ffff88809511fc28
> > > Data copied to user address 0000000020000298
> > > ==================================================================
> > >
> > >
> > > ---
> > > This bug is generated by a bot. It may contain errors.
> > > See https://goo.gl/tpsmEJ for more information about syzbot.
> > > syzbot engineers can be reached at [email protected].
> > >
> > > syzbot will keep track of this bug report. See:
> > > https://goo.gl/tpsmEJ#status for how to communicate with syzbot.
> > > syzbot can test patches for this bug, for details see:
> > > https://goo.gl/tpsmEJ#testing-patches
> > >
> > >
> >
> >
> > Hmm, odd. I see where we are doing the copy_to_user call in
> > getsockopt_peer_addrs, but the length we copy should always be equal to or less
> > than what was memcopied to the temp variable. False positive?
> I'll take a closer look next week.
> The bug is reproducible with the following syzkaller program:
>
> r0 = socket$inet(0x2, 0x80001, 0x84)
> bind$inet(r0, &(0x7f0000000080)={0x2, 0x4e20, @empty}, 0x10)
> sendmsg(r0, &(0x7f0000000100)={&(0x7f0000006000)=@in={0x2, 0x4e20,
> @loopback}, 0x80, &(0x7f0000007f80)=[{&(0x7f00000001c0)="de", 0x1}],
> 0x1}, 0x0)
> getsockopt$inet_sctp_SCTP_GET_PEER_ADDRS(r0, 0x84, 0x6c,
> &(0x7f0000000000)={<r5=>0x0, 0x38,
> "41925f90e4121fadc9c1296dd22ae19d0b1b0942e46fc79e2ecec1056b23199f0ca008915d8dba1b3896c154f2244bbe859fe3423a4b437a"},
> &(0x7f0000000040)=0x40)
>
> Just need to check where the uninitializedness comes from.
my only guess would be if we somehow copied an ipv4 address worth of data to the
buffer (which contains an enum for both ipv4 and ipv6 addresses), and then
copied an ipv6 address worth of data to userspace, but I don't yet see how that
can happen.
Neil
> > Neil
> >
>
>
>
> --
> Alexander Potapenko
> Software Engineer
>
> Google Germany GmbH
> Erika-Mann-Stra?e, 33
> 80636 M?nchen
>
> Gesch?ftsf?hrer: Paul Manicle, Halimah DeLaine Prado
> Registergericht und -nummer: Hamburg, HRB 86891
> Sitz der Gesellschaft: Hamburg
>
On Fri, Mar 29, 2019 at 7:31 PM Neil Horman <[email protected]> wrote:
>
> On Fri, Mar 29, 2019 at 06:35:40PM +0100, Alexander Potapenko wrote:
> > On Fri, Mar 29, 2019 at 3:51 PM Neil Horman <[email protected]> wrote:
> > >
> > > On Thu, Mar 28, 2019 at 09:25:06AM -0700, syzbot wrote:
> > > > Hello,
> > > >
> > > > syzbot found the following crash on:
> > > >
> > > > HEAD commit: c10a026b kmsan: use __free_pages() in kmsan_iounmap_page_r..
> > > > git tree: kmsan
> > > > console output: https://syzkaller.appspot.com/x/log.txt?x=107d3c7d200000
> > > > kernel config: https://syzkaller.appspot.com/x/.config?x=a5675814e8eae69e
> > > > dashboard link: https://syzkaller.appspot.com/bug?extid=86b5c7c236a22616a72f
> > > > compiler: clang version 8.0.0 (trunk 350509)
> > > > syz repro: https://syzkaller.appspot.com/x/repro.syz?x=1252834d200000
> > > >
> > > > IMPORTANT: if you fix the bug, please add the following tag to the commit:
> > > > Reported-by: [email protected]
> > > >
> > > > IPv6: ADDRCONF(NETDEV_CHANGE): veth1_to_hsr: link becomes ready
> > > > IPv6: ADDRCONF(NETDEV_CHANGE): hsr_slave_1: link becomes ready
> > > > 8021q: adding VLAN 0 to HW filter on device batadv0
> > > > 8021q: adding VLAN 0 to HW filter on device batadv0
> > > > ==================================================================
> > > > BUG: KMSAN: kernel-infoleak in _copy_to_user+0x16b/0x1f0 lib/usercopy.c:32
> > > > CPU: 0 PID: 10131 Comm: syz-executor.4 Not tainted 5.0.0+ #16
> > > > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
> > > > Google 01/01/2011
> > > > Call Trace:
> > > > __dump_stack lib/dump_stack.c:77 [inline]
> > > > dump_stack+0x173/0x1d0 lib/dump_stack.c:113
> > > > kmsan_report+0x131/0x2a0 mm/kmsan/kmsan.c:636
> > > > kmsan_internal_check_memory+0xaa1/0xbb0 mm/kmsan/kmsan.c:730
> > > > kmsan_copy_to_user+0xab/0xc0 mm/kmsan/kmsan_hooks.c:485
> > > > _copy_to_user+0x16b/0x1f0 lib/usercopy.c:32
> > > > copy_to_user include/linux/uaccess.h:174 [inline]
> > > > sctp_getsockopt_peer_addrs net/sctp/socket.c:5911 [inline]
> > > > sctp_getsockopt+0x1668e/0x17f70 net/sctp/socket.c:7562
> > > > sock_common_getsockopt+0x13f/0x180 net/core/sock.c:2950
> > > > __sys_getsockopt+0x489/0x550 net/socket.c:1938
> > > > __do_sys_getsockopt net/socket.c:1949 [inline]
> > > > __se_sys_getsockopt+0xe1/0x100 net/socket.c:1946
> > > > __x64_sys_getsockopt+0x62/0x80 net/socket.c:1946
> > > > do_syscall_64+0xbc/0xf0 arch/x86/entry/common.c:291
> > > > entry_SYSCALL_64_after_hwframe+0x63/0xe7
> > > > RIP: 0033:0x458209
> > > > Code: ad b8 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 48 89 f8 48 89 f7
> > > > 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff
> > > > 0f 83 7b b8 fb ff c3 66 2e 0f 1f 84 00 00 00 00
> > > > RSP: 002b:00007fdbef191c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000037
> > > > RAX: ffffffffffffffda RBX: 0000000000000005 RCX: 0000000000458209
> > > > RDX: 000000000000006c RSI: 0000000000000084 RDI: 0000000000000004
> > > > RBP: 000000000073bf00 R08: 0000000020000300 R09: 0000000000000000
> > > > R10: 0000000020000280 R11: 0000000000000246 R12: 00007fdbef1926d4
> > > > R13: 00000000004c96c8 R14: 00000000004d0310 R15: 00000000ffffffff
> > > >
> > > > Uninit was stored to memory at:
> > > > kmsan_save_stack_with_flags mm/kmsan/kmsan.c:205 [inline]
> > > > kmsan_save_stack mm/kmsan/kmsan.c:220 [inline]
> > > > kmsan_internal_chain_origin+0x134/0x230 mm/kmsan/kmsan.c:426
> > > > kmsan_memcpy_memmove_metadata+0xb5b/0xfe0 mm/kmsan/kmsan.c:304
> > > > kmsan_memcpy_metadata+0xb/0x10 mm/kmsan/kmsan.c:324
> > > > __msan_memcpy+0x58/0x70 mm/kmsan/kmsan_instr.c:139
> > > > sctp_getsockopt_peer_addrs net/sctp/socket.c:5906 [inline]
> > > > sctp_getsockopt+0x16556/0x17f70 net/sctp/socket.c:7562
> > > > sock_common_getsockopt+0x13f/0x180 net/core/sock.c:2950
> > > > __sys_getsockopt+0x489/0x550 net/socket.c:1938
> > > > __do_sys_getsockopt net/socket.c:1949 [inline]
> > > > __se_sys_getsockopt+0xe1/0x100 net/socket.c:1946
> > > > __x64_sys_getsockopt+0x62/0x80 net/socket.c:1946
> > > > do_syscall_64+0xbc/0xf0 arch/x86/entry/common.c:291
> > > > entry_SYSCALL_64_after_hwframe+0x63/0xe7
> > > >
> > > > Uninit was stored to memory at:
> > > > kmsan_save_stack_with_flags mm/kmsan/kmsan.c:205 [inline]
> > > > kmsan_save_stack mm/kmsan/kmsan.c:220 [inline]
> > > > kmsan_internal_chain_origin+0x134/0x230 mm/kmsan/kmsan.c:426
> > > > kmsan_memcpy_memmove_metadata+0xb5b/0xfe0 mm/kmsan/kmsan.c:304
> > > > kmsan_memcpy_metadata+0xb/0x10 mm/kmsan/kmsan.c:324
> > > > __msan_memcpy+0x58/0x70 mm/kmsan/kmsan_instr.c:139
> > > > sctp_transport_init net/sctp/transport.c:61 [inline]
> > > > sctp_transport_new+0x16d/0x9a0 net/sctp/transport.c:115
> > > > sctp_assoc_add_peer+0x532/0x1f70 net/sctp/associola.c:637
> > > > sctp_process_param net/sctp/sm_make_chunk.c:2548 [inline]
> > > > sctp_process_init+0x1a1b/0x3ed0 net/sctp/sm_make_chunk.c:2361
> > > > sctp_cmd_process_init net/sctp/sm_sideeffect.c:682 [inline]
> > > > sctp_cmd_interpreter net/sctp/sm_sideeffect.c:1410 [inline]
> > > > sctp_side_effects net/sctp/sm_sideeffect.c:1220 [inline]
> > > > sctp_do_sm+0x3cfc/0x9af0 net/sctp/sm_sideeffect.c:1191
> > > > sctp_assoc_bh_rcv+0x65a/0xd80 net/sctp/associola.c:1074
> > > > sctp_inq_push+0x300/0x420 net/sctp/inqueue.c:95
> > > > sctp_backlog_rcv+0x20a/0xaf0 net/sctp/input.c:354
> > > > sk_backlog_rcv include/net/sock.h:936 [inline]
> > > > __release_sock+0x281/0x5f0 net/core/sock.c:2284
> > > > release_sock+0x99/0x2a0 net/core/sock.c:2800
> > > > sctp_wait_for_connect+0x3ee/0x860 net/sctp/socket.c:8751
> > > > sctp_sendmsg_to_asoc+0x2167/0x21a0 net/sctp/socket.c:1967
> > > > sctp_sendmsg+0x3fd7/0x6700 net/sctp/socket.c:2113
> > > > inet_sendmsg+0x54a/0x720 net/ipv4/af_inet.c:798
> > > > sock_sendmsg_nosec net/socket.c:622 [inline]
> > > > sock_sendmsg net/socket.c:632 [inline]
> > > > ___sys_sendmsg+0xdb9/0x11b0 net/socket.c:2115
> > > > __sys_sendmsg net/socket.c:2153 [inline]
> > > > __do_sys_sendmsg net/socket.c:2162 [inline]
> > > > __se_sys_sendmsg+0x305/0x460 net/socket.c:2160
> > > > __x64_sys_sendmsg+0x4a/0x70 net/socket.c:2160
> > > > do_syscall_64+0xbc/0xf0 arch/x86/entry/common.c:291
> > > > entry_SYSCALL_64_after_hwframe+0x63/0xe7
> > > >
> > > > Local variable description: ----addr.i@sctp_process_init
> > > > Variable was created at:
> > > > sctp_process_init+0xb5/0x3ed0 net/sctp/sm_make_chunk.c:2324
> > > > sctp_cmd_process_init net/sctp/sm_sideeffect.c:682 [inline]
> > > > sctp_cmd_interpreter net/sctp/sm_sideeffect.c:1410 [inline]
> > > > sctp_side_effects net/sctp/sm_sideeffect.c:1220 [inline]
> > > > sctp_do_sm+0x3cfc/0x9af0 net/sctp/sm_sideeffect.c:1191
> > > >
> > > > Bytes 8-15 of 16 are uninitialized
> > > > Memory access of size 16 starts at ffff88809511fc28
> > > > Data copied to user address 0000000020000298
> > > > ==================================================================
> > > >
> > > >
> > > > ---
> > > > This bug is generated by a bot. It may contain errors.
> > > > See https://goo.gl/tpsmEJ for more information about syzbot.
> > > > syzbot engineers can be reached at [email protected].
> > > >
> > > > syzbot will keep track of this bug report. See:
> > > > https://goo.gl/tpsmEJ#status for how to communicate with syzbot.
> > > > syzbot can test patches for this bug, for details see:
> > > > https://goo.gl/tpsmEJ#testing-patches
> > > >
> > > >
> > >
> > >
> > > Hmm, odd. I see where we are doing the copy_to_user call in
> > > getsockopt_peer_addrs, but the length we copy should always be equal to or less
> > > than what was memcopied to the temp variable. False positive?
> > I'll take a closer look next week.
> > The bug is reproducible with the following syzkaller program:
> >
> > r0 = socket$inet(0x2, 0x80001, 0x84)
> > bind$inet(r0, &(0x7f0000000080)={0x2, 0x4e20, @empty}, 0x10)
> > sendmsg(r0, &(0x7f0000000100)={&(0x7f0000006000)=@in={0x2, 0x4e20,
> > @loopback}, 0x80, &(0x7f0000007f80)=[{&(0x7f00000001c0)="de", 0x1}],
> > 0x1}, 0x0)
> > getsockopt$inet_sctp_SCTP_GET_PEER_ADDRS(r0, 0x84, 0x6c,
> > &(0x7f0000000000)={<r5=>0x0, 0x38,
> > "41925f90e4121fadc9c1296dd22ae19d0b1b0942e46fc79e2ecec1056b23199f0ca008915d8dba1b3896c154f2244bbe859fe3423a4b437a"},
> > &(0x7f0000000040)=0x40)
> >
> > Just need to check where the uninitializedness comes from.
> my only guess would be if we somehow copied an ipv4 address worth of data to the
> buffer (which contains an enum for both ipv4 and ipv6 addresses), and then
> copied an ipv6 address worth of data to userspace,
This seems to partially confirm this:
> Bytes 8-15 of 16 are uninitialized
Not 4 bytes are initialized, but still half of the ipv6 addr.
> but I don't yet see how that
> can happen.
The repro says "#{"threaded":true,"collide":true,"repeat":true,"procs":6".
So I would assume there is a race somewhere.
On Sat, Mar 30, 2019 at 2:52 AM Dmitry Vyukov <[email protected]> wrote:
>
> On Fri, Mar 29, 2019 at 7:31 PM Neil Horman <[email protected]> wrote:
> >
> > On Fri, Mar 29, 2019 at 06:35:40PM +0100, Alexander Potapenko wrote:
> > > On Fri, Mar 29, 2019 at 3:51 PM Neil Horman <[email protected]> wrote:
> > > >
> > > > On Thu, Mar 28, 2019 at 09:25:06AM -0700, syzbot wrote:
> > > > > Hello,
> > > > >
> > > > > syzbot found the following crash on:
> > > > >
> > > > > HEAD commit: c10a026b kmsan: use __free_pages() in kmsan_iounmap_page_r..
> > > > > git tree: kmsan
> > > > > console output: https://syzkaller.appspot.com/x/log.txt?x=107d3c7d200000
> > > > > kernel config: https://syzkaller.appspot.com/x/.config?x=a5675814e8eae69e
> > > > > dashboard link: https://syzkaller.appspot.com/bug?extid=86b5c7c236a22616a72f
> > > > > compiler: clang version 8.0.0 (trunk 350509)
> > > > > syz repro: https://syzkaller.appspot.com/x/repro.syz?x=1252834d200000
> > > > >
> > > > > IMPORTANT: if you fix the bug, please add the following tag to the commit:
> > > > > Reported-by: [email protected]
> > > > >
> > > > > IPv6: ADDRCONF(NETDEV_CHANGE): veth1_to_hsr: link becomes ready
> > > > > IPv6: ADDRCONF(NETDEV_CHANGE): hsr_slave_1: link becomes ready
> > > > > 8021q: adding VLAN 0 to HW filter on device batadv0
> > > > > 8021q: adding VLAN 0 to HW filter on device batadv0
> > > > > ==================================================================
> > > > > BUG: KMSAN: kernel-infoleak in _copy_to_user+0x16b/0x1f0 lib/usercopy.c:32
> > > > > CPU: 0 PID: 10131 Comm: syz-executor.4 Not tainted 5.0.0+ #16
> > > > > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
> > > > > Google 01/01/2011
> > > > > Call Trace:
> > > > > __dump_stack lib/dump_stack.c:77 [inline]
> > > > > dump_stack+0x173/0x1d0 lib/dump_stack.c:113
> > > > > kmsan_report+0x131/0x2a0 mm/kmsan/kmsan.c:636
> > > > > kmsan_internal_check_memory+0xaa1/0xbb0 mm/kmsan/kmsan.c:730
> > > > > kmsan_copy_to_user+0xab/0xc0 mm/kmsan/kmsan_hooks.c:485
> > > > > _copy_to_user+0x16b/0x1f0 lib/usercopy.c:32
> > > > > copy_to_user include/linux/uaccess.h:174 [inline]
> > > > > sctp_getsockopt_peer_addrs net/sctp/socket.c:5911 [inline]
> > > > > sctp_getsockopt+0x1668e/0x17f70 net/sctp/socket.c:7562
> > > > > sock_common_getsockopt+0x13f/0x180 net/core/sock.c:2950
> > > > > __sys_getsockopt+0x489/0x550 net/socket.c:1938
> > > > > __do_sys_getsockopt net/socket.c:1949 [inline]
> > > > > __se_sys_getsockopt+0xe1/0x100 net/socket.c:1946
> > > > > __x64_sys_getsockopt+0x62/0x80 net/socket.c:1946
> > > > > do_syscall_64+0xbc/0xf0 arch/x86/entry/common.c:291
> > > > > entry_SYSCALL_64_after_hwframe+0x63/0xe7
> > > > > RIP: 0033:0x458209
> > > > > Code: ad b8 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 48 89 f8 48 89 f7
> > > > > 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff
> > > > > 0f 83 7b b8 fb ff c3 66 2e 0f 1f 84 00 00 00 00
> > > > > RSP: 002b:00007fdbef191c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000037
> > > > > RAX: ffffffffffffffda RBX: 0000000000000005 RCX: 0000000000458209
> > > > > RDX: 000000000000006c RSI: 0000000000000084 RDI: 0000000000000004
> > > > > RBP: 000000000073bf00 R08: 0000000020000300 R09: 0000000000000000
> > > > > R10: 0000000020000280 R11: 0000000000000246 R12: 00007fdbef1926d4
> > > > > R13: 00000000004c96c8 R14: 00000000004d0310 R15: 00000000ffffffff
> > > > >
> > > > > Uninit was stored to memory at:
> > > > > kmsan_save_stack_with_flags mm/kmsan/kmsan.c:205 [inline]
> > > > > kmsan_save_stack mm/kmsan/kmsan.c:220 [inline]
> > > > > kmsan_internal_chain_origin+0x134/0x230 mm/kmsan/kmsan.c:426
> > > > > kmsan_memcpy_memmove_metadata+0xb5b/0xfe0 mm/kmsan/kmsan.c:304
> > > > > kmsan_memcpy_metadata+0xb/0x10 mm/kmsan/kmsan.c:324
> > > > > __msan_memcpy+0x58/0x70 mm/kmsan/kmsan_instr.c:139
> > > > > sctp_getsockopt_peer_addrs net/sctp/socket.c:5906 [inline]
> > > > > sctp_getsockopt+0x16556/0x17f70 net/sctp/socket.c:7562
> > > > > sock_common_getsockopt+0x13f/0x180 net/core/sock.c:2950
> > > > > __sys_getsockopt+0x489/0x550 net/socket.c:1938
> > > > > __do_sys_getsockopt net/socket.c:1949 [inline]
> > > > > __se_sys_getsockopt+0xe1/0x100 net/socket.c:1946
> > > > > __x64_sys_getsockopt+0x62/0x80 net/socket.c:1946
> > > > > do_syscall_64+0xbc/0xf0 arch/x86/entry/common.c:291
> > > > > entry_SYSCALL_64_after_hwframe+0x63/0xe7
> > > > >
> > > > > Uninit was stored to memory at:
> > > > > kmsan_save_stack_with_flags mm/kmsan/kmsan.c:205 [inline]
> > > > > kmsan_save_stack mm/kmsan/kmsan.c:220 [inline]
> > > > > kmsan_internal_chain_origin+0x134/0x230 mm/kmsan/kmsan.c:426
> > > > > kmsan_memcpy_memmove_metadata+0xb5b/0xfe0 mm/kmsan/kmsan.c:304
> > > > > kmsan_memcpy_metadata+0xb/0x10 mm/kmsan/kmsan.c:324
> > > > > __msan_memcpy+0x58/0x70 mm/kmsan/kmsan_instr.c:139
> > > > > sctp_transport_init net/sctp/transport.c:61 [inline]
> > > > > sctp_transport_new+0x16d/0x9a0 net/sctp/transport.c:115
> > > > > sctp_assoc_add_peer+0x532/0x1f70 net/sctp/associola.c:637
> > > > > sctp_process_param net/sctp/sm_make_chunk.c:2548 [inline]
> > > > > sctp_process_init+0x1a1b/0x3ed0 net/sctp/sm_make_chunk.c:2361
> > > > > sctp_cmd_process_init net/sctp/sm_sideeffect.c:682 [inline]
> > > > > sctp_cmd_interpreter net/sctp/sm_sideeffect.c:1410 [inline]
> > > > > sctp_side_effects net/sctp/sm_sideeffect.c:1220 [inline]
> > > > > sctp_do_sm+0x3cfc/0x9af0 net/sctp/sm_sideeffect.c:1191
> > > > > sctp_assoc_bh_rcv+0x65a/0xd80 net/sctp/associola.c:1074
> > > > > sctp_inq_push+0x300/0x420 net/sctp/inqueue.c:95
> > > > > sctp_backlog_rcv+0x20a/0xaf0 net/sctp/input.c:354
> > > > > sk_backlog_rcv include/net/sock.h:936 [inline]
> > > > > __release_sock+0x281/0x5f0 net/core/sock.c:2284
> > > > > release_sock+0x99/0x2a0 net/core/sock.c:2800
> > > > > sctp_wait_for_connect+0x3ee/0x860 net/sctp/socket.c:8751
> > > > > sctp_sendmsg_to_asoc+0x2167/0x21a0 net/sctp/socket.c:1967
> > > > > sctp_sendmsg+0x3fd7/0x6700 net/sctp/socket.c:2113
> > > > > inet_sendmsg+0x54a/0x720 net/ipv4/af_inet.c:798
> > > > > sock_sendmsg_nosec net/socket.c:622 [inline]
> > > > > sock_sendmsg net/socket.c:632 [inline]
> > > > > ___sys_sendmsg+0xdb9/0x11b0 net/socket.c:2115
> > > > > __sys_sendmsg net/socket.c:2153 [inline]
> > > > > __do_sys_sendmsg net/socket.c:2162 [inline]
> > > > > __se_sys_sendmsg+0x305/0x460 net/socket.c:2160
> > > > > __x64_sys_sendmsg+0x4a/0x70 net/socket.c:2160
> > > > > do_syscall_64+0xbc/0xf0 arch/x86/entry/common.c:291
> > > > > entry_SYSCALL_64_after_hwframe+0x63/0xe7
> > > > >
> > > > > Local variable description: ----addr.i@sctp_process_init
> > > > > Variable was created at:
> > > > > sctp_process_init+0xb5/0x3ed0 net/sctp/sm_make_chunk.c:2324
> > > > > sctp_cmd_process_init net/sctp/sm_sideeffect.c:682 [inline]
> > > > > sctp_cmd_interpreter net/sctp/sm_sideeffect.c:1410 [inline]
> > > > > sctp_side_effects net/sctp/sm_sideeffect.c:1220 [inline]
> > > > > sctp_do_sm+0x3cfc/0x9af0 net/sctp/sm_sideeffect.c:1191
> > > > >
> > > > > Bytes 8-15 of 16 are uninitialized
> > > > > Memory access of size 16 starts at ffff88809511fc28
> > > > > Data copied to user address 0000000020000298
> > > > > ==================================================================
> > > > >
> > > > >
> > > > > ---
> > > > > This bug is generated by a bot. It may contain errors.
> > > > > See https://goo.gl/tpsmEJ for more information about syzbot.
> > > > > syzbot engineers can be reached at [email protected].
> > > > >
> > > > > syzbot will keep track of this bug report. See:
> > > > > https://goo.gl/tpsmEJ#status for how to communicate with syzbot.
> > > > > syzbot can test patches for this bug, for details see:
> > > > > https://goo.gl/tpsmEJ#testing-patches
> > > > >
> > > > >
> > > >
> > > >
> > > > Hmm, odd. I see where we are doing the copy_to_user call in
> > > > getsockopt_peer_addrs, but the length we copy should always be equal to or less
> > > > than what was memcopied to the temp variable. False positive?
> > > I'll take a closer look next week.
> > > The bug is reproducible with the following syzkaller program:
> > >
> > > r0 = socket$inet(0x2, 0x80001, 0x84)
> > > bind$inet(r0, &(0x7f0000000080)={0x2, 0x4e20, @empty}, 0x10)
> > > sendmsg(r0, &(0x7f0000000100)={&(0x7f0000006000)=@in={0x2, 0x4e20,
> > > @loopback}, 0x80, &(0x7f0000007f80)=[{&(0x7f00000001c0)="de", 0x1}],
> > > 0x1}, 0x0)
> > > getsockopt$inet_sctp_SCTP_GET_PEER_ADDRS(r0, 0x84, 0x6c,
> > > &(0x7f0000000000)={<r5=>0x0, 0x38,
> > > "41925f90e4121fadc9c1296dd22ae19d0b1b0942e46fc79e2ecec1056b23199f0ca008915d8dba1b3896c154f2244bbe859fe3423a4b437a"},
> > > &(0x7f0000000040)=0x40)
> > >
> > > Just need to check where the uninitializedness comes from.
> > my only guess would be if we somehow copied an ipv4 address worth of data to the
> > buffer (which contains an enum for both ipv4 and ipv6 addresses), and then
> > copied an ipv6 address worth of data to userspace,
>
> This seems to partially confirm this:
>
> > Bytes 8-15 of 16 are uninitialized
From the call trace, Uninit memory was stored in 'addr' when processing
SCTP_PARAM_IPV4_ADDRESS in sctp_process_param() by
af->from_addr_param/sctp_v4_from_addr_param, in which
addr->v4.sin_family/port/sin_addr was set, but not addr->v4._pad,
which maches, 8-15 of 16 are uninitialized.
Then it went to sctp_transport_init(), and set the addr directly to
peer->ipaddr and added the new transport into asoc->peer.transport_addr_list.
When dumping peer_addrs in sctp_getsockopt_peer_addrs():
memcpy(&temp, &from->ipaddr, sizeof(temp));
copy_to_user(to, &temp, addrlen),
addrlen is sizeof(struct sockaddr_in), 16 bytes, but only the first 8
bytes were inited.
So we should fix it by setting addr->v4._pad in sctp_v4_addr_to_user as
sctp_v6_addr_to_user does:
@@ -600,6 +600,7 @@ static struct sock
*sctp_v4_create_accept_sk(struct sock *sk,
static int sctp_v4_addr_to_user(struct sctp_sock *sp, union sctp_addr *addr)
{
/* No address mapping for V4 sockets */
+ memset(addr->v4.sin_zero, 0, sizeof(addr->v4.sin_zero));
return sizeof(struct sockaddr_in);
}
>
> Not 4 bytes are initialized, but still half of the ipv6 addr.
>
>
> > but I don't yet see how that
> > can happen.
>
> The repro says "#{"threaded":true,"collide":true,"repeat":true,"procs":6".
> So I would assume there is a race somewhere.
On Sat, Mar 30, 2019 at 8:20 AM Xin Long <[email protected]> wrote:
>
> On Sat, Mar 30, 2019 at 2:52 AM Dmitry Vyukov <[email protected]> wrote:
> >
> > On Fri, Mar 29, 2019 at 7:31 PM Neil Horman <[email protected]> wrote:
> > >
> > > On Fri, Mar 29, 2019 at 06:35:40PM +0100, Alexander Potapenko wrote:
> > > > On Fri, Mar 29, 2019 at 3:51 PM Neil Horman <[email protected]> wrote:
> > > > >
> > > > > On Thu, Mar 28, 2019 at 09:25:06AM -0700, syzbot wrote:
> > > > > > Hello,
> > > > > >
> > > > > > syzbot found the following crash on:
> > > > > >
> > > > > > HEAD commit: c10a026b kmsan: use __free_pages() in kmsan_iounmap_page_r..
> > > > > > git tree: kmsan
> > > > > > console output: https://syzkaller.appspot.com/x/log.txt?x=107d3c7d200000
> > > > > > kernel config: https://syzkaller.appspot.com/x/.config?x=a5675814e8eae69e
> > > > > > dashboard link: https://syzkaller.appspot.com/bug?extid=86b5c7c236a22616a72f
> > > > > > compiler: clang version 8.0.0 (trunk 350509)
> > > > > > syz repro: https://syzkaller.appspot.com/x/repro.syz?x=1252834d200000
> > > > > >
> > > > > > IMPORTANT: if you fix the bug, please add the following tag to the commit:
> > > > > > Reported-by: [email protected]
> > > > > >
> > > > > > IPv6: ADDRCONF(NETDEV_CHANGE): veth1_to_hsr: link becomes ready
> > > > > > IPv6: ADDRCONF(NETDEV_CHANGE): hsr_slave_1: link becomes ready
> > > > > > 8021q: adding VLAN 0 to HW filter on device batadv0
> > > > > > 8021q: adding VLAN 0 to HW filter on device batadv0
> > > > > > ==================================================================
> > > > > > BUG: KMSAN: kernel-infoleak in _copy_to_user+0x16b/0x1f0 lib/usercopy.c:32
> > > > > > CPU: 0 PID: 10131 Comm: syz-executor.4 Not tainted 5.0.0+ #16
> > > > > > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
> > > > > > Google 01/01/2011
> > > > > > Call Trace:
> > > > > > __dump_stack lib/dump_stack.c:77 [inline]
> > > > > > dump_stack+0x173/0x1d0 lib/dump_stack.c:113
> > > > > > kmsan_report+0x131/0x2a0 mm/kmsan/kmsan.c:636
> > > > > > kmsan_internal_check_memory+0xaa1/0xbb0 mm/kmsan/kmsan.c:730
> > > > > > kmsan_copy_to_user+0xab/0xc0 mm/kmsan/kmsan_hooks.c:485
> > > > > > _copy_to_user+0x16b/0x1f0 lib/usercopy.c:32
> > > > > > copy_to_user include/linux/uaccess.h:174 [inline]
> > > > > > sctp_getsockopt_peer_addrs net/sctp/socket.c:5911 [inline]
> > > > > > sctp_getsockopt+0x1668e/0x17f70 net/sctp/socket.c:7562
> > > > > > sock_common_getsockopt+0x13f/0x180 net/core/sock.c:2950
> > > > > > __sys_getsockopt+0x489/0x550 net/socket.c:1938
> > > > > > __do_sys_getsockopt net/socket.c:1949 [inline]
> > > > > > __se_sys_getsockopt+0xe1/0x100 net/socket.c:1946
> > > > > > __x64_sys_getsockopt+0x62/0x80 net/socket.c:1946
> > > > > > do_syscall_64+0xbc/0xf0 arch/x86/entry/common.c:291
> > > > > > entry_SYSCALL_64_after_hwframe+0x63/0xe7
> > > > > > RIP: 0033:0x458209
> > > > > > Code: ad b8 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 48 89 f8 48 89 f7
> > > > > > 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff
> > > > > > 0f 83 7b b8 fb ff c3 66 2e 0f 1f 84 00 00 00 00
> > > > > > RSP: 002b:00007fdbef191c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000037
> > > > > > RAX: ffffffffffffffda RBX: 0000000000000005 RCX: 0000000000458209
> > > > > > RDX: 000000000000006c RSI: 0000000000000084 RDI: 0000000000000004
> > > > > > RBP: 000000000073bf00 R08: 0000000020000300 R09: 0000000000000000
> > > > > > R10: 0000000020000280 R11: 0000000000000246 R12: 00007fdbef1926d4
> > > > > > R13: 00000000004c96c8 R14: 00000000004d0310 R15: 00000000ffffffff
> > > > > >
> > > > > > Uninit was stored to memory at:
> > > > > > kmsan_save_stack_with_flags mm/kmsan/kmsan.c:205 [inline]
> > > > > > kmsan_save_stack mm/kmsan/kmsan.c:220 [inline]
> > > > > > kmsan_internal_chain_origin+0x134/0x230 mm/kmsan/kmsan.c:426
> > > > > > kmsan_memcpy_memmove_metadata+0xb5b/0xfe0 mm/kmsan/kmsan.c:304
> > > > > > kmsan_memcpy_metadata+0xb/0x10 mm/kmsan/kmsan.c:324
> > > > > > __msan_memcpy+0x58/0x70 mm/kmsan/kmsan_instr.c:139
> > > > > > sctp_getsockopt_peer_addrs net/sctp/socket.c:5906 [inline]
> > > > > > sctp_getsockopt+0x16556/0x17f70 net/sctp/socket.c:7562
> > > > > > sock_common_getsockopt+0x13f/0x180 net/core/sock.c:2950
> > > > > > __sys_getsockopt+0x489/0x550 net/socket.c:1938
> > > > > > __do_sys_getsockopt net/socket.c:1949 [inline]
> > > > > > __se_sys_getsockopt+0xe1/0x100 net/socket.c:1946
> > > > > > __x64_sys_getsockopt+0x62/0x80 net/socket.c:1946
> > > > > > do_syscall_64+0xbc/0xf0 arch/x86/entry/common.c:291
> > > > > > entry_SYSCALL_64_after_hwframe+0x63/0xe7
> > > > > >
> > > > > > Uninit was stored to memory at:
> > > > > > kmsan_save_stack_with_flags mm/kmsan/kmsan.c:205 [inline]
> > > > > > kmsan_save_stack mm/kmsan/kmsan.c:220 [inline]
> > > > > > kmsan_internal_chain_origin+0x134/0x230 mm/kmsan/kmsan.c:426
> > > > > > kmsan_memcpy_memmove_metadata+0xb5b/0xfe0 mm/kmsan/kmsan.c:304
> > > > > > kmsan_memcpy_metadata+0xb/0x10 mm/kmsan/kmsan.c:324
> > > > > > __msan_memcpy+0x58/0x70 mm/kmsan/kmsan_instr.c:139
> > > > > > sctp_transport_init net/sctp/transport.c:61 [inline]
> > > > > > sctp_transport_new+0x16d/0x9a0 net/sctp/transport.c:115
> > > > > > sctp_assoc_add_peer+0x532/0x1f70 net/sctp/associola.c:637
> > > > > > sctp_process_param net/sctp/sm_make_chunk.c:2548 [inline]
> > > > > > sctp_process_init+0x1a1b/0x3ed0 net/sctp/sm_make_chunk.c:2361
> > > > > > sctp_cmd_process_init net/sctp/sm_sideeffect.c:682 [inline]
> > > > > > sctp_cmd_interpreter net/sctp/sm_sideeffect.c:1410 [inline]
> > > > > > sctp_side_effects net/sctp/sm_sideeffect.c:1220 [inline]
> > > > > > sctp_do_sm+0x3cfc/0x9af0 net/sctp/sm_sideeffect.c:1191
> > > > > > sctp_assoc_bh_rcv+0x65a/0xd80 net/sctp/associola.c:1074
> > > > > > sctp_inq_push+0x300/0x420 net/sctp/inqueue.c:95
> > > > > > sctp_backlog_rcv+0x20a/0xaf0 net/sctp/input.c:354
> > > > > > sk_backlog_rcv include/net/sock.h:936 [inline]
> > > > > > __release_sock+0x281/0x5f0 net/core/sock.c:2284
> > > > > > release_sock+0x99/0x2a0 net/core/sock.c:2800
> > > > > > sctp_wait_for_connect+0x3ee/0x860 net/sctp/socket.c:8751
> > > > > > sctp_sendmsg_to_asoc+0x2167/0x21a0 net/sctp/socket.c:1967
> > > > > > sctp_sendmsg+0x3fd7/0x6700 net/sctp/socket.c:2113
> > > > > > inet_sendmsg+0x54a/0x720 net/ipv4/af_inet.c:798
> > > > > > sock_sendmsg_nosec net/socket.c:622 [inline]
> > > > > > sock_sendmsg net/socket.c:632 [inline]
> > > > > > ___sys_sendmsg+0xdb9/0x11b0 net/socket.c:2115
> > > > > > __sys_sendmsg net/socket.c:2153 [inline]
> > > > > > __do_sys_sendmsg net/socket.c:2162 [inline]
> > > > > > __se_sys_sendmsg+0x305/0x460 net/socket.c:2160
> > > > > > __x64_sys_sendmsg+0x4a/0x70 net/socket.c:2160
> > > > > > do_syscall_64+0xbc/0xf0 arch/x86/entry/common.c:291
> > > > > > entry_SYSCALL_64_after_hwframe+0x63/0xe7
> > > > > >
> > > > > > Local variable description: ----addr.i@sctp_process_init
> > > > > > Variable was created at:
> > > > > > sctp_process_init+0xb5/0x3ed0 net/sctp/sm_make_chunk.c:2324
> > > > > > sctp_cmd_process_init net/sctp/sm_sideeffect.c:682 [inline]
> > > > > > sctp_cmd_interpreter net/sctp/sm_sideeffect.c:1410 [inline]
> > > > > > sctp_side_effects net/sctp/sm_sideeffect.c:1220 [inline]
> > > > > > sctp_do_sm+0x3cfc/0x9af0 net/sctp/sm_sideeffect.c:1191
> > > > > >
> > > > > > Bytes 8-15 of 16 are uninitialized
> > > > > > Memory access of size 16 starts at ffff88809511fc28
> > > > > > Data copied to user address 0000000020000298
> > > > > > ==================================================================
> > > > > >
> > > > > >
> > > > > > ---
> > > > > > This bug is generated by a bot. It may contain errors.
> > > > > > See https://goo.gl/tpsmEJ for more information about syzbot.
> > > > > > syzbot engineers can be reached at [email protected].
> > > > > >
> > > > > > syzbot will keep track of this bug report. See:
> > > > > > https://goo.gl/tpsmEJ#status for how to communicate with syzbot.
> > > > > > syzbot can test patches for this bug, for details see:
> > > > > > https://goo.gl/tpsmEJ#testing-patches
> > > > > >
> > > > > >
> > > > >
> > > > >
> > > > > Hmm, odd. I see where we are doing the copy_to_user call in
> > > > > getsockopt_peer_addrs, but the length we copy should always be equal to or less
> > > > > than what was memcopied to the temp variable. False positive?
> > > > I'll take a closer look next week.
> > > > The bug is reproducible with the following syzkaller program:
> > > >
> > > > r0 = socket$inet(0x2, 0x80001, 0x84)
> > > > bind$inet(r0, &(0x7f0000000080)={0x2, 0x4e20, @empty}, 0x10)
> > > > sendmsg(r0, &(0x7f0000000100)={&(0x7f0000006000)=@in={0x2, 0x4e20,
> > > > @loopback}, 0x80, &(0x7f0000007f80)=[{&(0x7f00000001c0)="de", 0x1}],
> > > > 0x1}, 0x0)
> > > > getsockopt$inet_sctp_SCTP_GET_PEER_ADDRS(r0, 0x84, 0x6c,
> > > > &(0x7f0000000000)={<r5=>0x0, 0x38,
> > > > "41925f90e4121fadc9c1296dd22ae19d0b1b0942e46fc79e2ecec1056b23199f0ca008915d8dba1b3896c154f2244bbe859fe3423a4b437a"},
> > > > &(0x7f0000000040)=0x40)
> > > >
> > > > Just need to check where the uninitializedness comes from.
> > > my only guess would be if we somehow copied an ipv4 address worth of data to the
> > > buffer (which contains an enum for both ipv4 and ipv6 addresses), and then
> > > copied an ipv6 address worth of data to userspace,
> >
> > This seems to partially confirm this:
> >
> > > Bytes 8-15 of 16 are uninitialized
> From the call trace, Uninit memory was stored in 'addr' when processing
> SCTP_PARAM_IPV4_ADDRESS in sctp_process_param() by
> af->from_addr_param/sctp_v4_from_addr_param, in which
> addr->v4.sin_family/port/sin_addr was set, but not addr->v4._pad,
> which maches, 8-15 of 16 are uninitialized.
>
> Then it went to sctp_transport_init(), and set the addr directly to
> peer->ipaddr and added the new transport into asoc->peer.transport_addr_list.
Thanks for the analysis!
> When dumping peer_addrs in sctp_getsockopt_peer_addrs():
>
> memcpy(&temp, &from->ipaddr, sizeof(temp));
> copy_to_user(to, &temp, addrlen),
>
> addrlen is sizeof(struct sockaddr_in), 16 bytes, but only the first 8
> bytes were inited.
>
> So we should fix it by setting addr->v4._pad in sctp_v4_addr_to_user as
> sctp_v6_addr_to_user does:
>
> @@ -600,6 +600,7 @@ static struct sock
> *sctp_v4_create_accept_sk(struct sock *sk,
> static int sctp_v4_addr_to_user(struct sctp_sock *sp, union sctp_addr *addr)
> {
> /* No address mapping for V4 sockets */
> + memset(addr->v4.sin_zero, 0, sizeof(addr->v4.sin_zero));
> return sizeof(struct sockaddr_in);
> }
I can confirm this is a valid fix.
>
> >
> > Not 4 bytes are initialized, but still half of the ipv6 addr.
> >
> >
> > > but I don't yet see how that
> > > can happen.
> >
> > The repro says "#{"threaded":true,"collide":true,"repeat":true,"procs":6".
> > So I would assume there is a race somewhere.
--
Alexander Potapenko
Software Engineer
Google Germany GmbH
Erika-Mann-Straße, 33
80636 München
Geschäftsführer: Paul Manicle, Halimah DeLaine Prado
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Sitz der Gesellschaft: Hamburg