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

[Dmitry Vyukov]

On Tue, Jan 15, 2019 at 5:43 AM syzbot
<syzbot+bd36b7dd9330f67037ab@xxxxxxxxxxxxxxxxxxxxxxxxx> 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@xxxxxxxxxxxxxxxxxxxxxxxxx
>
> ==================================================================
> 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
> `9ïïïïïï#ï(  ïïïïï<ïïïïï  kïïïïïïïEïïïïï>9hïïïïïïïïA/-2122188634
>
> CPU: 0 PID: -2122188634 Comm: ïïEïïïïïïïïïïïïïO2ï 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: ïïEïïïïïïïïïïïïïO2ï 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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