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b=IxAJjWhBv/6wwBbIHee0vJrdRSNAhYd8hW2Y/4KvVHYhb1A6VwldydtAw47JKNfAHc E46c11cpwQojzuk3d89kofEEXwPUWBUhp4z5HihJpu6HQ4Rnnxst8yUYMSyuU096T/It KEqiLif6+owLmgEHe0Trmq/NU8jnp9huIhSq6rFMaaJRO0cUqy0VSCBQ/qjobex7patd TaYaNAIOiDsZoePU8so974HCy3VEfZtyH/4MXaZjEJMQvqMk6yOF07sw/HPaWatqj/Ha ltzJ5E6EWl77vAr8TxfL8qyeagNz6bRPr/VGOOOvfngfszUx3ZbfncyRJUNSNrgM7h0V qXpg== X-Gm-Message-State: APjAAAXYwqWndSk0yh6va5NIqfDKosQJwBaZTP5oTVBgDEHIh6XNXR87 +Jgv3exP0oP/Gn9EB0z9UJrGZQAvEU1hlzrZnVOL7g== X-Received: by 2002:ab0:270f:: with SMTP id s15mr29181398uao.110.1553880952164; Fri, 29 Mar 2019 10:35:52 -0700 (PDT) MIME-Version: 1.0 References: <000000000000407080058529ff40@google.com> <20190329123025.GB30213@hmswarspite.think-freely.org> In-Reply-To: <20190329123025.GB30213@hmswarspite.think-freely.org> From: Alexander Potapenko Date: Fri, 29 Mar 2019 18:35:40 +0100 Message-ID: Subject: Re: KMSAN: kernel-infoleak in sctp_getsockopt (3) To: Neil Horman Cc: syzbot , David Miller , LKML , linux-sctp@vger.kernel.org, Marcelo Ricardo Leitner , Networking , syzkaller-bugs , Vladislav Yasevich Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Mar 29, 2019 at 3:51 PM Neil Horman 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_pag= e_r.. > > git tree: kmsan > > console output: https://syzkaller.appspot.com/x/log.txt?x=3D107d3c7d200= 000 > > kernel config: https://syzkaller.appspot.com/x/.config?x=3Da5675814e8e= ae69e > > dashboard link: https://syzkaller.appspot.com/bug?extid=3D86b5c7c236a22= 616a72f > > compiler: clang version 8.0.0 (trunk 350509) > > syz repro: https://syzkaller.appspot.com/x/repro.syz?x=3D1252834d2= 00000 > > > > IMPORTANT: if you fix the bug, please add the following tag to the comm= it: > > Reported-by: syzbot+86b5c7c236a22616a72f@syzkaller.appspotmail.com > > > > 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 > > =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D > > 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 > > =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D > > > > > > --- > > 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 syzkaller@googlegroups.com. > > > > 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 o= r 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 =3D socket$inet(0x2, 0x80001, 0x84) bind$inet(r0, &(0x7f0000000080)=3D{0x2, 0x4e20, @empty}, 0x10) sendmsg(r0, &(0x7f0000000100)=3D{&(0x7f0000006000)=3D@in=3D{0x2, 0x4e20, @loopback}, 0x80, &(0x7f0000007f80)=3D[{&(0x7f00000001c0)=3D"de", 0x1}], 0x1}, 0x0) getsockopt$inet_sctp_SCTP_GET_PEER_ADDRS(r0, 0x84, 0x6c, &(0x7f0000000000)=3D{0x0, 0x38, "41925f90e4121fadc9c1296dd22ae19d0b1b0942e46fc79e2ecec1056b23199f0ca008915d= 8dba1b3896c154f2244bbe859fe3423a4b437a"}, &(0x7f0000000040)=3D0x40) Just need to check where the uninitializedness comes from. > Neil > -- Alexander Potapenko Software Engineer Google Germany GmbH Erika-Mann-Stra=C3=9Fe, 33 80636 M=C3=BCnchen Gesch=C3=A4ftsf=C3=BChrer: Paul Manicle, Halimah DeLaine Prado Registergericht und -nummer: Hamburg, HRB 86891 Sitz der Gesellschaft: Hamburg