KASAN: use-after-scope Read in corrupted

KASAN: use-after-scope Read in corrupted

[syzbot]

Hello,

syzbot found the following crash on:

HEAD commit:    1bdbe2274920 Merge tag 'vfio-v5.0-rc2' of git://github.com..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=1519d39f400000
kernel config:  https://syzkaller.appspot.com/x/.config?x=edf1c3031097c304
dashboard link: https://syzkaller.appspot.com/bug?extid=bd36b7dd9330f67037ab
compiler:       gcc (GCC) 9.0.0 20181231 (experimental)
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=10fce14f400000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=110b2017400000

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+bd36b7dd9330f67037ab@syzkaller.appspotmail.com

==================================================================
BUG: KASAN: use-after-scope in debug_lockdep_rcu_enabled.part.0+0x50/0x60  
kernel/rcu/update.c:249
Read of size 4 at addr ffff8880a945eabc by task  
`9������#�(\x15\x10�����<�����\x10\x1ak�������E�����>9h��������A/-2122188634

CPU: 0 PID: -2122188634 Comm: ��E�������������O2� Not tainted 5.0.0-rc1+  
#19
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS  
Google 01/01/2011
------------[ cut here ]------------
Bad or missing usercopy whitelist? Kernel memory overwrite attempt detected  
to SLAB object 'task_struct' (offset 1344, size 8)!
WARNING: CPU: 0 PID: -1455036288 at mm/usercopy.c:78  
usercopy_warn+0xeb/0x110 mm/usercopy.c:78
Kernel panic - not syncing: panic_on_warn set ...
CPU: 0 PID: -1455036288 Comm: ��E�������������O2� Not tainted 5.0.0-rc1+  
#19
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS  
Google 01/01/2011
Call Trace:
Kernel Offset: disabled
Rebooting in 86400 seconds..


---
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Re: KASAN: use-after-scope Read in corrupted

[Dmitry Vyukov]

On Tue, Jan 15, 2019 at 5:43 AM syzbot
<syzbot+bd36b7dd9330f67037ab@syzkaller.appspotmail.com> wrote:
>
> Hello,
>
> syzbot found the following crash on:
>
> HEAD commit:    1bdbe2274920 Merge tag 'vfio-v5.0-rc2' of git://github.com..
> git tree:       upstream
> console output: https://syzkaller.appspot.com/x/log.txt?x=1519d39f400000
> kernel config:  https://syzkaller.appspot.com/x/.config?x=edf1c3031097c304
> dashboard link: https://syzkaller.appspot.com/bug?extid=bd36b7dd9330f67037ab
> compiler:       gcc (GCC) 9.0.0 20181231 (experimental)
> syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=10fce14f400000
> C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=110b2017400000

Based on the reproducer this is:

#syz dup: kernel panic: stack is corrupted in udp4_lib_lookup2


> IMPORTANT: if you fix the bug, please add the following tag to the commit:
> Reported-by: syzbot+bd36b7dd9330f67037ab@syzkaller.appspotmail.com
>
> ==================================================================
> BUG: KASAN: use-after-scope in debug_lockdep_rcu_enabled.part.0+0x50/0x60
> kernel/rcu/update.c:249
> Read of size 4 at addr ffff8880a945eabc by task
> `9������#�(  �����<�����  k�������E�����>9h��������A/-2122188634
>
> CPU: 0 PID: -2122188634 Comm: ��E�������������O2� Not tainted 5.0.0-rc1+
> #19
> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
> Google 01/01/2011
> ------------[ cut here ]------------
> Bad or missing usercopy whitelist? Kernel memory overwrite attempt detected
> to SLAB object 'task_struct' (offset 1344, size 8)!
> WARNING: CPU: 0 PID: -1455036288 at mm/usercopy.c:78
> usercopy_warn+0xeb/0x110 mm/usercopy.c:78
> Kernel panic - not syncing: panic_on_warn set ...
> CPU: 0 PID: -1455036288 Comm: ��E�������������O2� Not tainted 5.0.0-rc1+
> #19
> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
> Google 01/01/2011
> Call Trace:
> Kernel Offset: disabled
> Rebooting in 86400 seconds..
>
>
> ---
> 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#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
>
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