Hello,
syzbot found the following crash on:
HEAD commit: 123906095e30 kmsan: introduce kmsan_interrupt_enter()/kmsa..
git tree: https://github.com/google/kmsan.git/master
console output: https://syzkaller.appspot.com/x/log.txt?x=1249fcb8400000
kernel config: https://syzkaller.appspot.com/x/.config?x=848e40757852af3e
dashboard link: https://syzkaller.appspot.com/bug?extid=2dcfeaf8cb49b05e8f1a
compiler: clang version 7.0.0 (trunk 334104)
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=116ef050400000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=122870ff800000
IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: [email protected]
random: sshd: uninitialized urandom read (32 bytes read)
==================================================================
BUG: KMSAN: kernel-infoleak in copyout lib/iov_iter.c:140 [inline]
BUG: KMSAN: kernel-infoleak in copy_page_to_iter_iovec lib/iov_iter.c:212
[inline]
BUG: KMSAN: kernel-infoleak in copy_page_to_iter+0x754/0x1b70
lib/iov_iter.c:716
CPU: 0 PID: 4516 Comm: blkid Not tainted 4.17.0+ #9
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+0x185/0x1d0 lib/dump_stack.c:113
kmsan_report+0x188/0x2a0 mm/kmsan/kmsan.c:1125
kmsan_internal_check_memory+0x17e/0x1f0 mm/kmsan/kmsan.c:1238
kmsan_copy_to_user+0x7a/0x160 mm/kmsan/kmsan.c:1261
copyout lib/iov_iter.c:140 [inline]
copy_page_to_iter_iovec lib/iov_iter.c:212 [inline]
copy_page_to_iter+0x754/0x1b70 lib/iov_iter.c:716
generic_file_buffered_read mm/filemap.c:2185 [inline]
generic_file_read_iter+0x2ef8/0x44d0 mm/filemap.c:2362
blkdev_read_iter+0x20d/0x280 fs/block_dev.c:1930
call_read_iter include/linux/fs.h:1778 [inline]
new_sync_read fs/read_write.c:406 [inline]
__vfs_read+0x775/0x9d0 fs/read_write.c:418
vfs_read+0x36c/0x6b0 fs/read_write.c:452
ksys_read fs/read_write.c:578 [inline]
__do_sys_read fs/read_write.c:588 [inline]
__se_sys_read fs/read_write.c:586 [inline]
__x64_sys_read+0x1bf/0x3e0 fs/read_write.c:586
do_syscall_64+0x15b/0x230 arch/x86/entry/common.c:287
entry_SYSCALL_64_after_hwframe+0x44/0xa9
RIP: 0033:0x7fdeff68f310
RSP: 002b:00007ffe999660b8 EFLAGS: 00000246 ORIG_RAX: 0000000000000000
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007fdeff68f310
RDX: 0000000000000100 RSI: 0000000001e78df8 RDI: 0000000000000003
RBP: 0000000001e78dd0 R08: 0000000000000028 R09: 0000000001680000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000001e78030
R13: 0000000000000100 R14: 0000000001e78080 R15: 0000000001e78de8
Uninit was created at:
kmsan_save_stack_with_flags mm/kmsan/kmsan.c:282 [inline]
kmsan_alloc_meta_for_pages+0x161/0x3a0 mm/kmsan/kmsan.c:819
kmsan_alloc_page+0x82/0xe0 mm/kmsan/kmsan.c:889
__alloc_pages_nodemask+0xf7b/0x5cc0 mm/page_alloc.c:4402
alloc_pages_current+0x6b1/0x970 mm/mempolicy.c:2093
alloc_pages include/linux/gfp.h:494 [inline]
__page_cache_alloc+0x95/0x320 mm/filemap.c:946
pagecache_get_page+0x52b/0x1450 mm/filemap.c:1577
grab_cache_page_write_begin+0x10d/0x190 mm/filemap.c:3089
block_write_begin+0xf9/0x3a0 fs/buffer.c:2068
blkdev_write_begin+0xf5/0x110 fs/block_dev.c:584
generic_perform_write+0x438/0x9d0 mm/filemap.c:3139
__generic_file_write_iter+0x43b/0xa10 mm/filemap.c:3264
blkdev_write_iter+0x3a8/0x5f0 fs/block_dev.c:1910
do_iter_readv_writev+0x81c/0xa20 include/linux/fs.h:1778
do_iter_write+0x30d/0xd50 fs/read_write.c:959
vfs_writev fs/read_write.c:1004 [inline]
do_writev+0x3be/0x820 fs/read_write.c:1039
__do_sys_writev fs/read_write.c:1112 [inline]
__se_sys_writev fs/read_write.c:1109 [inline]
__x64_sys_writev+0xe1/0x120 fs/read_write.c:1109
do_syscall_64+0x15b/0x230 arch/x86/entry/common.c:287
entry_SYSCALL_64_after_hwframe+0x44/0xa9
Bytes 4-255 of 256 are uninitialized
Memory access starts at ffff8801b9903000
==================================================================
---
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#bug-status-tracking for how to communicate with
syzbot.
syzbot can test patches for this bug, for details see:
https://goo.gl/tpsmEJ#testing-patches
On Thu, Sep 13, 2018 at 11:18 AM syzbot
<[email protected]> wrote:
>
> Hello,
>
> syzbot found the following crash on:
>
> HEAD commit: 123906095e30 kmsan: introduce kmsan_interrupt_enter()/kmsa..
> git tree: https://github.com/google/kmsan.git/master
> console output: https://syzkaller.appspot.com/x/log.txt?x=1249fcb8400000
> kernel config: https://syzkaller.appspot.com/x/.config?x=848e40757852af3e
> dashboard link: https://syzkaller.appspot.com/bug?extid=2dcfeaf8cb49b05e8f1a
> compiler: clang version 7.0.0 (trunk 334104)
> syz repro: https://syzkaller.appspot.com/x/repro.syz?x=116ef050400000
> C reproducer: https://syzkaller.appspot.com/x/repro.c?x=122870ff800000
>
> IMPORTANT: if you fix the bug, please add the following tag to the commit:
> Reported-by: [email protected]
>
> random: sshd: uninitialized urandom read (32 bytes read)
> ==================================================================
> BUG: KMSAN: kernel-infoleak in copyout lib/iov_iter.c:140 [inline]
> BUG: KMSAN: kernel-infoleak in copy_page_to_iter_iovec lib/iov_iter.c:212
> [inline]
> BUG: KMSAN: kernel-infoleak in copy_page_to_iter+0x754/0x1b70
> lib/iov_iter.c:716
> CPU: 0 PID: 4516 Comm: blkid Not tainted 4.17.0+ #9
> 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+0x185/0x1d0 lib/dump_stack.c:113
> kmsan_report+0x188/0x2a0 mm/kmsan/kmsan.c:1125
> kmsan_internal_check_memory+0x17e/0x1f0 mm/kmsan/kmsan.c:1238
> kmsan_copy_to_user+0x7a/0x160 mm/kmsan/kmsan.c:1261
> copyout lib/iov_iter.c:140 [inline]
> copy_page_to_iter_iovec lib/iov_iter.c:212 [inline]
> copy_page_to_iter+0x754/0x1b70 lib/iov_iter.c:716
> generic_file_buffered_read mm/filemap.c:2185 [inline]
> generic_file_read_iter+0x2ef8/0x44d0 mm/filemap.c:2362
> blkdev_read_iter+0x20d/0x280 fs/block_dev.c:1930
> call_read_iter include/linux/fs.h:1778 [inline]
> new_sync_read fs/read_write.c:406 [inline]
> __vfs_read+0x775/0x9d0 fs/read_write.c:418
> vfs_read+0x36c/0x6b0 fs/read_write.c:452
> ksys_read fs/read_write.c:578 [inline]
> __do_sys_read fs/read_write.c:588 [inline]
> __se_sys_read fs/read_write.c:586 [inline]
> __x64_sys_read+0x1bf/0x3e0 fs/read_write.c:586
> do_syscall_64+0x15b/0x230 arch/x86/entry/common.c:287
> entry_SYSCALL_64_after_hwframe+0x44/0xa9
> RIP: 0033:0x7fdeff68f310
> RSP: 002b:00007ffe999660b8 EFLAGS: 00000246 ORIG_RAX: 0000000000000000
> RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007fdeff68f310
> RDX: 0000000000000100 RSI: 0000000001e78df8 RDI: 0000000000000003
> RBP: 0000000001e78dd0 R08: 0000000000000028 R09: 0000000001680000
> R10: 0000000000000000 R11: 0000000000000246 R12: 0000000001e78030
> R13: 0000000000000100 R14: 0000000001e78080 R15: 0000000001e78de8
>
> Uninit was created at:
> kmsan_save_stack_with_flags mm/kmsan/kmsan.c:282 [inline]
> kmsan_alloc_meta_for_pages+0x161/0x3a0 mm/kmsan/kmsan.c:819
> kmsan_alloc_page+0x82/0xe0 mm/kmsan/kmsan.c:889
> __alloc_pages_nodemask+0xf7b/0x5cc0 mm/page_alloc.c:4402
> alloc_pages_current+0x6b1/0x970 mm/mempolicy.c:2093
> alloc_pages include/linux/gfp.h:494 [inline]
> __page_cache_alloc+0x95/0x320 mm/filemap.c:946
> pagecache_get_page+0x52b/0x1450 mm/filemap.c:1577
> grab_cache_page_write_begin+0x10d/0x190 mm/filemap.c:3089
> block_write_begin+0xf9/0x3a0 fs/buffer.c:2068
> blkdev_write_begin+0xf5/0x110 fs/block_dev.c:584
> generic_perform_write+0x438/0x9d0 mm/filemap.c:3139
> __generic_file_write_iter+0x43b/0xa10 mm/filemap.c:3264
> blkdev_write_iter+0x3a8/0x5f0 fs/block_dev.c:1910
> do_iter_readv_writev+0x81c/0xa20 include/linux/fs.h:1778
> do_iter_write+0x30d/0xd50 fs/read_write.c:959
> vfs_writev fs/read_write.c:1004 [inline]
> do_writev+0x3be/0x820 fs/read_write.c:1039
> __do_sys_writev fs/read_write.c:1112 [inline]
> __se_sys_writev fs/read_write.c:1109 [inline]
> __x64_sys_writev+0xe1/0x120 fs/read_write.c:1109
> do_syscall_64+0x15b/0x230 arch/x86/entry/common.c:287
> entry_SYSCALL_64_after_hwframe+0x44/0xa9
>
> Bytes 4-255 of 256 are uninitialized
> Memory access starts at ffff8801b9903000
> ==================================================================
This particular report was caused by the repro program writing a byte
to /dev/nullb0 and /sbin/blkid reading from that device in the
background.
But it turns out that simply running `cat /dev/nullb0` already prints
uninitialized kernel memory.
Is this the intended behavior of the null block driver?
>
> ---
> 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#bug-status-tracking for how to communicate with
> syzbot.
> syzbot can test patches for this bug, for details see:
> https://goo.gl/tpsmEJ#testing-patches
>
> --
> You received this message because you are subscribed to the Google Groups "syzkaller-bugs" group.
> To unsubscribe from this group and stop receiving emails from it, send an email to [email protected].
> To view this discussion on the web visit https://groups.google.com/d/msgid/syzkaller-bugs/00000000000016eb330575bd2fab%40google.com.
> For more options, visit https://groups.google.com/d/optout.
--
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 Thu, Sep 13, 2018 at 11:23 AM Alexander Potapenko <[email protected]> wrote:
>
> On Thu, Sep 13, 2018 at 11:18 AM syzbot
> <[email protected]> wrote:
> >
> > Hello,
> >
> > syzbot found the following crash on:
> >
> > HEAD commit: 123906095e30 kmsan: introduce kmsan_interrupt_enter()/kmsa..
> > git tree: https://github.com/google/kmsan.git/master
> > console output: https://syzkaller.appspot.com/x/log.txt?x=1249fcb8400000
> > kernel config: https://syzkaller.appspot.com/x/.config?x=848e40757852af3e
> > dashboard link: https://syzkaller.appspot.com/bug?extid=2dcfeaf8cb49b05e8f1a
> > compiler: clang version 7.0.0 (trunk 334104)
> > syz repro: https://syzkaller.appspot.com/x/repro.syz?x=116ef050400000
> > C reproducer: https://syzkaller.appspot.com/x/repro.c?x=122870ff800000
> >
> > IMPORTANT: if you fix the bug, please add the following tag to the commit:
> > Reported-by: [email protected]
> >
> > random: sshd: uninitialized urandom read (32 bytes read)
> > ==================================================================
> > BUG: KMSAN: kernel-infoleak in copyout lib/iov_iter.c:140 [inline]
> > BUG: KMSAN: kernel-infoleak in copy_page_to_iter_iovec lib/iov_iter.c:212
> > [inline]
> > BUG: KMSAN: kernel-infoleak in copy_page_to_iter+0x754/0x1b70
> > lib/iov_iter.c:716
> > CPU: 0 PID: 4516 Comm: blkid Not tainted 4.17.0+ #9
> > 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+0x185/0x1d0 lib/dump_stack.c:113
> > kmsan_report+0x188/0x2a0 mm/kmsan/kmsan.c:1125
> > kmsan_internal_check_memory+0x17e/0x1f0 mm/kmsan/kmsan.c:1238
> > kmsan_copy_to_user+0x7a/0x160 mm/kmsan/kmsan.c:1261
> > copyout lib/iov_iter.c:140 [inline]
> > copy_page_to_iter_iovec lib/iov_iter.c:212 [inline]
> > copy_page_to_iter+0x754/0x1b70 lib/iov_iter.c:716
> > generic_file_buffered_read mm/filemap.c:2185 [inline]
> > generic_file_read_iter+0x2ef8/0x44d0 mm/filemap.c:2362
> > blkdev_read_iter+0x20d/0x280 fs/block_dev.c:1930
> > call_read_iter include/linux/fs.h:1778 [inline]
> > new_sync_read fs/read_write.c:406 [inline]
> > __vfs_read+0x775/0x9d0 fs/read_write.c:418
> > vfs_read+0x36c/0x6b0 fs/read_write.c:452
> > ksys_read fs/read_write.c:578 [inline]
> > __do_sys_read fs/read_write.c:588 [inline]
> > __se_sys_read fs/read_write.c:586 [inline]
> > __x64_sys_read+0x1bf/0x3e0 fs/read_write.c:586
> > do_syscall_64+0x15b/0x230 arch/x86/entry/common.c:287
> > entry_SYSCALL_64_after_hwframe+0x44/0xa9
> > RIP: 0033:0x7fdeff68f310
> > RSP: 002b:00007ffe999660b8 EFLAGS: 00000246 ORIG_RAX: 0000000000000000
> > RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007fdeff68f310
> > RDX: 0000000000000100 RSI: 0000000001e78df8 RDI: 0000000000000003
> > RBP: 0000000001e78dd0 R08: 0000000000000028 R09: 0000000001680000
> > R10: 0000000000000000 R11: 0000000000000246 R12: 0000000001e78030
> > R13: 0000000000000100 R14: 0000000001e78080 R15: 0000000001e78de8
> >
> > Uninit was created at:
> > kmsan_save_stack_with_flags mm/kmsan/kmsan.c:282 [inline]
> > kmsan_alloc_meta_for_pages+0x161/0x3a0 mm/kmsan/kmsan.c:819
> > kmsan_alloc_page+0x82/0xe0 mm/kmsan/kmsan.c:889
> > __alloc_pages_nodemask+0xf7b/0x5cc0 mm/page_alloc.c:4402
> > alloc_pages_current+0x6b1/0x970 mm/mempolicy.c:2093
> > alloc_pages include/linux/gfp.h:494 [inline]
> > __page_cache_alloc+0x95/0x320 mm/filemap.c:946
> > pagecache_get_page+0x52b/0x1450 mm/filemap.c:1577
> > grab_cache_page_write_begin+0x10d/0x190 mm/filemap.c:3089
> > block_write_begin+0xf9/0x3a0 fs/buffer.c:2068
> > blkdev_write_begin+0xf5/0x110 fs/block_dev.c:584
> > generic_perform_write+0x438/0x9d0 mm/filemap.c:3139
> > __generic_file_write_iter+0x43b/0xa10 mm/filemap.c:3264
> > blkdev_write_iter+0x3a8/0x5f0 fs/block_dev.c:1910
> > do_iter_readv_writev+0x81c/0xa20 include/linux/fs.h:1778
> > do_iter_write+0x30d/0xd50 fs/read_write.c:959
> > vfs_writev fs/read_write.c:1004 [inline]
> > do_writev+0x3be/0x820 fs/read_write.c:1039
> > __do_sys_writev fs/read_write.c:1112 [inline]
> > __se_sys_writev fs/read_write.c:1109 [inline]
> > __x64_sys_writev+0xe1/0x120 fs/read_write.c:1109
> > do_syscall_64+0x15b/0x230 arch/x86/entry/common.c:287
> > entry_SYSCALL_64_after_hwframe+0x44/0xa9
> >
> > Bytes 4-255 of 256 are uninitialized
> > Memory access starts at ffff8801b9903000
> > ==================================================================
> This particular report was caused by the repro program writing a byte
> to /dev/nullb0 and /sbin/blkid reading from that device in the
> background.
> But it turns out that simply running `cat /dev/nullb0` already prints
> uninitialized kernel memory.
> Is this the intended behavior of the null block driver?
A friendly ping, this bug is still reproducible on syzbot.
> > ---
> > 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#bug-status-tracking for how to communicate with
> > syzbot.
> > syzbot can test patches for this bug, for details see:
> > https://goo.gl/tpsmEJ#testing-patches
> >
> > --
> > You received this message because you are subscribed to the Google Groups "syzkaller-bugs" group.
> > To unsubscribe from this group and stop receiving emails from it, send an email to [email protected].
> > To view this discussion on the web visit https://groups.google.com/d/msgid/syzkaller-bugs/00000000000016eb330575bd2fab%40google.com.
> > For more options, visit https://groups.google.com/d/optout.
>
>
>
> --
> 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
--
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 12/19/18 3:23 AM, Alexander Potapenko wrote:
> On Thu, Sep 13, 2018 at 11:23 AM Alexander Potapenko <[email protected]> wrote:
>>
>> On Thu, Sep 13, 2018 at 11:18 AM syzbot
>> <[email protected]> wrote:
>>>
>>> Hello,
>>>
>>> syzbot found the following crash on:
>>>
>>> HEAD commit: 123906095e30 kmsan: introduce kmsan_interrupt_enter()/kmsa..
>>> git tree: https://github.com/google/kmsan.git/master
>>> console output: https://syzkaller.appspot.com/x/log.txt?x=1249fcb8400000
>>> kernel config: https://syzkaller.appspot.com/x/.config?x=848e40757852af3e
>>> dashboard link: https://syzkaller.appspot.com/bug?extid=2dcfeaf8cb49b05e8f1a
>>> compiler: clang version 7.0.0 (trunk 334104)
>>> syz repro: https://syzkaller.appspot.com/x/repro.syz?x=116ef050400000
>>> C reproducer: https://syzkaller.appspot.com/x/repro.c?x=122870ff800000
>>>
>>> IMPORTANT: if you fix the bug, please add the following tag to the commit:
>>> Reported-by: [email protected]
>>>
>>> random: sshd: uninitialized urandom read (32 bytes read)
>>> ==================================================================
>>> BUG: KMSAN: kernel-infoleak in copyout lib/iov_iter.c:140 [inline]
>>> BUG: KMSAN: kernel-infoleak in copy_page_to_iter_iovec lib/iov_iter.c:212
>>> [inline]
>>> BUG: KMSAN: kernel-infoleak in copy_page_to_iter+0x754/0x1b70
>>> lib/iov_iter.c:716
>>> CPU: 0 PID: 4516 Comm: blkid Not tainted 4.17.0+ #9
>>> 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+0x185/0x1d0 lib/dump_stack.c:113
>>> kmsan_report+0x188/0x2a0 mm/kmsan/kmsan.c:1125
>>> kmsan_internal_check_memory+0x17e/0x1f0 mm/kmsan/kmsan.c:1238
>>> kmsan_copy_to_user+0x7a/0x160 mm/kmsan/kmsan.c:1261
>>> copyout lib/iov_iter.c:140 [inline]
>>> copy_page_to_iter_iovec lib/iov_iter.c:212 [inline]
>>> copy_page_to_iter+0x754/0x1b70 lib/iov_iter.c:716
>>> generic_file_buffered_read mm/filemap.c:2185 [inline]
>>> generic_file_read_iter+0x2ef8/0x44d0 mm/filemap.c:2362
>>> blkdev_read_iter+0x20d/0x280 fs/block_dev.c:1930
>>> call_read_iter include/linux/fs.h:1778 [inline]
>>> new_sync_read fs/read_write.c:406 [inline]
>>> __vfs_read+0x775/0x9d0 fs/read_write.c:418
>>> vfs_read+0x36c/0x6b0 fs/read_write.c:452
>>> ksys_read fs/read_write.c:578 [inline]
>>> __do_sys_read fs/read_write.c:588 [inline]
>>> __se_sys_read fs/read_write.c:586 [inline]
>>> __x64_sys_read+0x1bf/0x3e0 fs/read_write.c:586
>>> do_syscall_64+0x15b/0x230 arch/x86/entry/common.c:287
>>> entry_SYSCALL_64_after_hwframe+0x44/0xa9
>>> RIP: 0033:0x7fdeff68f310
>>> RSP: 002b:00007ffe999660b8 EFLAGS: 00000246 ORIG_RAX: 0000000000000000
>>> RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007fdeff68f310
>>> RDX: 0000000000000100 RSI: 0000000001e78df8 RDI: 0000000000000003
>>> RBP: 0000000001e78dd0 R08: 0000000000000028 R09: 0000000001680000
>>> R10: 0000000000000000 R11: 0000000000000246 R12: 0000000001e78030
>>> R13: 0000000000000100 R14: 0000000001e78080 R15: 0000000001e78de8
>>>
>>> Uninit was created at:
>>> kmsan_save_stack_with_flags mm/kmsan/kmsan.c:282 [inline]
>>> kmsan_alloc_meta_for_pages+0x161/0x3a0 mm/kmsan/kmsan.c:819
>>> kmsan_alloc_page+0x82/0xe0 mm/kmsan/kmsan.c:889
>>> __alloc_pages_nodemask+0xf7b/0x5cc0 mm/page_alloc.c:4402
>>> alloc_pages_current+0x6b1/0x970 mm/mempolicy.c:2093
>>> alloc_pages include/linux/gfp.h:494 [inline]
>>> __page_cache_alloc+0x95/0x320 mm/filemap.c:946
>>> pagecache_get_page+0x52b/0x1450 mm/filemap.c:1577
>>> grab_cache_page_write_begin+0x10d/0x190 mm/filemap.c:3089
>>> block_write_begin+0xf9/0x3a0 fs/buffer.c:2068
>>> blkdev_write_begin+0xf5/0x110 fs/block_dev.c:584
>>> generic_perform_write+0x438/0x9d0 mm/filemap.c:3139
>>> __generic_file_write_iter+0x43b/0xa10 mm/filemap.c:3264
>>> blkdev_write_iter+0x3a8/0x5f0 fs/block_dev.c:1910
>>> do_iter_readv_writev+0x81c/0xa20 include/linux/fs.h:1778
>>> do_iter_write+0x30d/0xd50 fs/read_write.c:959
>>> vfs_writev fs/read_write.c:1004 [inline]
>>> do_writev+0x3be/0x820 fs/read_write.c:1039
>>> __do_sys_writev fs/read_write.c:1112 [inline]
>>> __se_sys_writev fs/read_write.c:1109 [inline]
>>> __x64_sys_writev+0xe1/0x120 fs/read_write.c:1109
>>> do_syscall_64+0x15b/0x230 arch/x86/entry/common.c:287
>>> entry_SYSCALL_64_after_hwframe+0x44/0xa9
>>>
>>> Bytes 4-255 of 256 are uninitialized
>>> Memory access starts at ffff8801b9903000
>>> ==================================================================
>> This particular report was caused by the repro program writing a byte
>> to /dev/nullb0 and /sbin/blkid reading from that device in the
>> background.
>> But it turns out that simply running `cat /dev/nullb0` already prints
>> uninitialized kernel memory.
>> Is this the intended behavior of the null block driver?
> A friendly ping, this bug is still reproducible on syzbot.
Does this fix it?
diff --git a/drivers/block/null_blk_main.c b/drivers/block/null_blk_main.c
index 62c9654b9ce8..08808c572692 100644
--- a/drivers/block/null_blk_main.c
+++ b/drivers/block/null_blk_main.c
@@ -655,7 +655,7 @@ static struct nullb_page *null_alloc_page(gfp_t gfp_flags)
if (!t_page)
goto out;
- t_page->page = alloc_pages(gfp_flags, 0);
+ t_page->page = alloc_pages(gfp_flags | __GFP_ZERO, 0);
if (!t_page->page)
goto out_freepage;
--
Jens Axboe
On Wed, Dec 19, 2018 at 2:23 PM Jens Axboe <[email protected]> wrote:
>
> On 12/19/18 3:23 AM, Alexander Potapenko wrote:
> > On Thu, Sep 13, 2018 at 11:23 AM Alexander Potapenko <[email protected]> wrote:
> >>
> >> On Thu, Sep 13, 2018 at 11:18 AM syzbot
> >> <[email protected]> wrote:
> >>>
> >>> Hello,
> >>>
> >>> syzbot found the following crash on:
> >>>
> >>> HEAD commit: 123906095e30 kmsan: introduce kmsan_interrupt_enter()/kmsa..
> >>> git tree: https://github.com/google/kmsan.git/master
> >>> console output: https://syzkaller.appspot.com/x/log.txt?x=1249fcb8400000
> >>> kernel config: https://syzkaller.appspot.com/x/.config?x=848e40757852af3e
> >>> dashboard link: https://syzkaller.appspot.com/bug?extid=2dcfeaf8cb49b05e8f1a
> >>> compiler: clang version 7.0.0 (trunk 334104)
> >>> syz repro: https://syzkaller.appspot.com/x/repro.syz?x=116ef050400000
> >>> C reproducer: https://syzkaller.appspot.com/x/repro.c?x=122870ff800000
> >>>
> >>> IMPORTANT: if you fix the bug, please add the following tag to the commit:
> >>> Reported-by: [email protected]
> >>>
> >>> random: sshd: uninitialized urandom read (32 bytes read)
> >>> ==================================================================
> >>> BUG: KMSAN: kernel-infoleak in copyout lib/iov_iter.c:140 [inline]
> >>> BUG: KMSAN: kernel-infoleak in copy_page_to_iter_iovec lib/iov_iter.c:212
> >>> [inline]
> >>> BUG: KMSAN: kernel-infoleak in copy_page_to_iter+0x754/0x1b70
> >>> lib/iov_iter.c:716
> >>> CPU: 0 PID: 4516 Comm: blkid Not tainted 4.17.0+ #9
> >>> 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+0x185/0x1d0 lib/dump_stack.c:113
> >>> kmsan_report+0x188/0x2a0 mm/kmsan/kmsan.c:1125
> >>> kmsan_internal_check_memory+0x17e/0x1f0 mm/kmsan/kmsan.c:1238
> >>> kmsan_copy_to_user+0x7a/0x160 mm/kmsan/kmsan.c:1261
> >>> copyout lib/iov_iter.c:140 [inline]
> >>> copy_page_to_iter_iovec lib/iov_iter.c:212 [inline]
> >>> copy_page_to_iter+0x754/0x1b70 lib/iov_iter.c:716
> >>> generic_file_buffered_read mm/filemap.c:2185 [inline]
> >>> generic_file_read_iter+0x2ef8/0x44d0 mm/filemap.c:2362
> >>> blkdev_read_iter+0x20d/0x280 fs/block_dev.c:1930
> >>> call_read_iter include/linux/fs.h:1778 [inline]
> >>> new_sync_read fs/read_write.c:406 [inline]
> >>> __vfs_read+0x775/0x9d0 fs/read_write.c:418
> >>> vfs_read+0x36c/0x6b0 fs/read_write.c:452
> >>> ksys_read fs/read_write.c:578 [inline]
> >>> __do_sys_read fs/read_write.c:588 [inline]
> >>> __se_sys_read fs/read_write.c:586 [inline]
> >>> __x64_sys_read+0x1bf/0x3e0 fs/read_write.c:586
> >>> do_syscall_64+0x15b/0x230 arch/x86/entry/common.c:287
> >>> entry_SYSCALL_64_after_hwframe+0x44/0xa9
> >>> RIP: 0033:0x7fdeff68f310
> >>> RSP: 002b:00007ffe999660b8 EFLAGS: 00000246 ORIG_RAX: 0000000000000000
> >>> RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007fdeff68f310
> >>> RDX: 0000000000000100 RSI: 0000000001e78df8 RDI: 0000000000000003
> >>> RBP: 0000000001e78dd0 R08: 0000000000000028 R09: 0000000001680000
> >>> R10: 0000000000000000 R11: 0000000000000246 R12: 0000000001e78030
> >>> R13: 0000000000000100 R14: 0000000001e78080 R15: 0000000001e78de8
> >>>
> >>> Uninit was created at:
> >>> kmsan_save_stack_with_flags mm/kmsan/kmsan.c:282 [inline]
> >>> kmsan_alloc_meta_for_pages+0x161/0x3a0 mm/kmsan/kmsan.c:819
> >>> kmsan_alloc_page+0x82/0xe0 mm/kmsan/kmsan.c:889
> >>> __alloc_pages_nodemask+0xf7b/0x5cc0 mm/page_alloc.c:4402
> >>> alloc_pages_current+0x6b1/0x970 mm/mempolicy.c:2093
> >>> alloc_pages include/linux/gfp.h:494 [inline]
> >>> __page_cache_alloc+0x95/0x320 mm/filemap.c:946
> >>> pagecache_get_page+0x52b/0x1450 mm/filemap.c:1577
> >>> grab_cache_page_write_begin+0x10d/0x190 mm/filemap.c:3089
> >>> block_write_begin+0xf9/0x3a0 fs/buffer.c:2068
> >>> blkdev_write_begin+0xf5/0x110 fs/block_dev.c:584
> >>> generic_perform_write+0x438/0x9d0 mm/filemap.c:3139
> >>> __generic_file_write_iter+0x43b/0xa10 mm/filemap.c:3264
> >>> blkdev_write_iter+0x3a8/0x5f0 fs/block_dev.c:1910
> >>> do_iter_readv_writev+0x81c/0xa20 include/linux/fs.h:1778
> >>> do_iter_write+0x30d/0xd50 fs/read_write.c:959
> >>> vfs_writev fs/read_write.c:1004 [inline]
> >>> do_writev+0x3be/0x820 fs/read_write.c:1039
> >>> __do_sys_writev fs/read_write.c:1112 [inline]
> >>> __se_sys_writev fs/read_write.c:1109 [inline]
> >>> __x64_sys_writev+0xe1/0x120 fs/read_write.c:1109
> >>> do_syscall_64+0x15b/0x230 arch/x86/entry/common.c:287
> >>> entry_SYSCALL_64_after_hwframe+0x44/0xa9
> >>>
> >>> Bytes 4-255 of 256 are uninitialized
> >>> Memory access starts at ffff8801b9903000
> >>> ==================================================================
> >> This particular report was caused by the repro program writing a byte
> >> to /dev/nullb0 and /sbin/blkid reading from that device in the
> >> background.
> >> But it turns out that simply running `cat /dev/nullb0` already prints
> >> uninitialized kernel memory.
> >> Is this the intended behavior of the null block driver?
> > A friendly ping, this bug is still reproducible on syzbot.
>
> Does this fix it?
There must be something wrong with my tool, as it stops reporting this
bug when I apply your patch.
However when I run `cat /dev/nullb0 | strings` and wait long enough I
start seeing meaningful strings (file names, env dumps etc.)
I suspect this is still unexpected, right?
>
> diff --git a/drivers/block/null_blk_main.c b/drivers/block/null_blk_main.c
> index 62c9654b9ce8..08808c572692 100644
> --- a/drivers/block/null_blk_main.c
> +++ b/drivers/block/null_blk_main.c
> @@ -655,7 +655,7 @@ static struct nullb_page *null_alloc_page(gfp_t gfp_flags)
> if (!t_page)
> goto out;
>
> - t_page->page = alloc_pages(gfp_flags, 0);
> + t_page->page = alloc_pages(gfp_flags | __GFP_ZERO, 0);
> if (!t_page->page)
> goto out_freepage;
>
>
> --
> Jens Axboe
>
--
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
From: Alexander Potapenko <[email protected]>
Date: Wed, Jan 2, 2019 at 11:09 AM
To: Jens Axboe
Cc: Andrew Morton, <[email protected]>,
<[email protected]>, Andi Kleen, <[email protected]>,
<[email protected]>, LKML, Linux Memory Management List,
<[email protected]>, <[email protected]>,
<[email protected]>
> On Wed, Dec 19, 2018 at 2:23 PM Jens Axboe <[email protected]> wrote:
> >
> > On 12/19/18 3:23 AM, Alexander Potapenko wrote:
> > > On Thu, Sep 13, 2018 at 11:23 AM Alexander Potapenko <[email protected]> wrote:
> > >>
> > >> On Thu, Sep 13, 2018 at 11:18 AM syzbot
> > >> <[email protected]> wrote:
> > >>>
> > >>> Hello,
> > >>>
> > >>> syzbot found the following crash on:
> > >>>
> > >>> HEAD commit: 123906095e30 kmsan: introduce kmsan_interrupt_enter()/kmsa..
> > >>> git tree: https://github.com/google/kmsan.git/master
> > >>> console output: https://syzkaller.appspot.com/x/log.txt?x=1249fcb8400000
> > >>> kernel config: https://syzkaller.appspot.com/x/.config?x=848e40757852af3e
> > >>> dashboard link: https://syzkaller.appspot.com/bug?extid=2dcfeaf8cb49b05e8f1a
> > >>> compiler: clang version 7.0.0 (trunk 334104)
> > >>> syz repro: https://syzkaller.appspot.com/x/repro.syz?x=116ef050400000
> > >>> C reproducer: https://syzkaller.appspot.com/x/repro.c?x=122870ff800000
> > >>>
> > >>> IMPORTANT: if you fix the bug, please add the following tag to the commit:
> > >>> Reported-by: [email protected]
> > >>>
> > >>> random: sshd: uninitialized urandom read (32 bytes read)
> > >>> ==================================================================
> > >>> BUG: KMSAN: kernel-infoleak in copyout lib/iov_iter.c:140 [inline]
> > >>> BUG: KMSAN: kernel-infoleak in copy_page_to_iter_iovec lib/iov_iter.c:212
> > >>> [inline]
> > >>> BUG: KMSAN: kernel-infoleak in copy_page_to_iter+0x754/0x1b70
> > >>> lib/iov_iter.c:716
> > >>> CPU: 0 PID: 4516 Comm: blkid Not tainted 4.17.0+ #9
> > >>> 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+0x185/0x1d0 lib/dump_stack.c:113
> > >>> kmsan_report+0x188/0x2a0 mm/kmsan/kmsan.c:1125
> > >>> kmsan_internal_check_memory+0x17e/0x1f0 mm/kmsan/kmsan.c:1238
> > >>> kmsan_copy_to_user+0x7a/0x160 mm/kmsan/kmsan.c:1261
> > >>> copyout lib/iov_iter.c:140 [inline]
> > >>> copy_page_to_iter_iovec lib/iov_iter.c:212 [inline]
> > >>> copy_page_to_iter+0x754/0x1b70 lib/iov_iter.c:716
> > >>> generic_file_buffered_read mm/filemap.c:2185 [inline]
> > >>> generic_file_read_iter+0x2ef8/0x44d0 mm/filemap.c:2362
> > >>> blkdev_read_iter+0x20d/0x280 fs/block_dev.c:1930
> > >>> call_read_iter include/linux/fs.h:1778 [inline]
> > >>> new_sync_read fs/read_write.c:406 [inline]
> > >>> __vfs_read+0x775/0x9d0 fs/read_write.c:418
> > >>> vfs_read+0x36c/0x6b0 fs/read_write.c:452
> > >>> ksys_read fs/read_write.c:578 [inline]
> > >>> __do_sys_read fs/read_write.c:588 [inline]
> > >>> __se_sys_read fs/read_write.c:586 [inline]
> > >>> __x64_sys_read+0x1bf/0x3e0 fs/read_write.c:586
> > >>> do_syscall_64+0x15b/0x230 arch/x86/entry/common.c:287
> > >>> entry_SYSCALL_64_after_hwframe+0x44/0xa9
> > >>> RIP: 0033:0x7fdeff68f310
> > >>> RSP: 002b:00007ffe999660b8 EFLAGS: 00000246 ORIG_RAX: 0000000000000000
> > >>> RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007fdeff68f310
> > >>> RDX: 0000000000000100 RSI: 0000000001e78df8 RDI: 0000000000000003
> > >>> RBP: 0000000001e78dd0 R08: 0000000000000028 R09: 0000000001680000
> > >>> R10: 0000000000000000 R11: 0000000000000246 R12: 0000000001e78030
> > >>> R13: 0000000000000100 R14: 0000000001e78080 R15: 0000000001e78de8
> > >>>
> > >>> Uninit was created at:
> > >>> kmsan_save_stack_with_flags mm/kmsan/kmsan.c:282 [inline]
> > >>> kmsan_alloc_meta_for_pages+0x161/0x3a0 mm/kmsan/kmsan.c:819
> > >>> kmsan_alloc_page+0x82/0xe0 mm/kmsan/kmsan.c:889
> > >>> __alloc_pages_nodemask+0xf7b/0x5cc0 mm/page_alloc.c:4402
> > >>> alloc_pages_current+0x6b1/0x970 mm/mempolicy.c:2093
> > >>> alloc_pages include/linux/gfp.h:494 [inline]
> > >>> __page_cache_alloc+0x95/0x320 mm/filemap.c:946
> > >>> pagecache_get_page+0x52b/0x1450 mm/filemap.c:1577
> > >>> grab_cache_page_write_begin+0x10d/0x190 mm/filemap.c:3089
> > >>> block_write_begin+0xf9/0x3a0 fs/buffer.c:2068
> > >>> blkdev_write_begin+0xf5/0x110 fs/block_dev.c:584
> > >>> generic_perform_write+0x438/0x9d0 mm/filemap.c:3139
> > >>> __generic_file_write_iter+0x43b/0xa10 mm/filemap.c:3264
> > >>> blkdev_write_iter+0x3a8/0x5f0 fs/block_dev.c:1910
> > >>> do_iter_readv_writev+0x81c/0xa20 include/linux/fs.h:1778
> > >>> do_iter_write+0x30d/0xd50 fs/read_write.c:959
> > >>> vfs_writev fs/read_write.c:1004 [inline]
> > >>> do_writev+0x3be/0x820 fs/read_write.c:1039
> > >>> __do_sys_writev fs/read_write.c:1112 [inline]
> > >>> __se_sys_writev fs/read_write.c:1109 [inline]
> > >>> __x64_sys_writev+0xe1/0x120 fs/read_write.c:1109
> > >>> do_syscall_64+0x15b/0x230 arch/x86/entry/common.c:287
> > >>> entry_SYSCALL_64_after_hwframe+0x44/0xa9
> > >>>
> > >>> Bytes 4-255 of 256 are uninitialized
> > >>> Memory access starts at ffff8801b9903000
> > >>> ==================================================================
> > >> This particular report was caused by the repro program writing a byte
> > >> to /dev/nullb0 and /sbin/blkid reading from that device in the
> > >> background.
> > >> But it turns out that simply running `cat /dev/nullb0` already prints
> > >> uninitialized kernel memory.
> > >> Is this the intended behavior of the null block driver?
> > > A friendly ping, this bug is still reproducible on syzbot.
> >
> > Does this fix it?
> There must be something wrong with my tool, as it stops reporting this
> bug when I apply your patch.
> However when I run `cat /dev/nullb0 | strings` and wait long enough I
> start seeing meaningful strings (file names, env dumps etc.)
> I suspect this is still unexpected, right?
A friendly ping, as we're still seeing similar errors.
> > diff --git a/drivers/block/null_blk_main.c b/drivers/block/null_blk_main.c
> > index 62c9654b9ce8..08808c572692 100644
> > --- a/drivers/block/null_blk_main.c
> > +++ b/drivers/block/null_blk_main.c
> > @@ -655,7 +655,7 @@ static struct nullb_page *null_alloc_page(gfp_t gfp_flags)
> > if (!t_page)
> > goto out;
> >
> > - t_page->page = alloc_pages(gfp_flags, 0);
> > + t_page->page = alloc_pages(gfp_flags | __GFP_ZERO, 0);
> > if (!t_page->page)
> > goto out_freepage;
> >
> >
> > --
> > Jens Axboe
> >
>
>
> --
> 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
--
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