Re: KASAN: slab-out-of-bounds Read in corrupted (2)

[Dmitry Vyukov]

On Thu, Jun 6, 2019 at 3:52 PM syzbot
<syzbot+9a901acbc447313bfe3e@xxxxxxxxxxxxxxxxxxxxxxxxx> wrote:
>
> Hello,
>
> syzbot found the following crash on:
>
> HEAD commit:    156c0591 Merge tag 'linux-kselftest-5.2-rc4' of git://git...
> git tree:       upstream
> console output: https://syzkaller.appspot.com/x/log.txt?x=13512d51a00000
> kernel config:  https://syzkaller.appspot.com/x/.config?x=60564cb52ab29d5b
> dashboard link: https://syzkaller.appspot.com/bug?extid=9a901acbc447313bfe3e
> compiler:       gcc (GCC) 9.0.0 20181231 (experimental)
> syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=11a4b01ea00000

Looks +bpf related from the repro.

> IMPORTANT: if you fix the bug, please add the following tag to the commit:
> Reported-by: syzbot+9a901acbc447313bfe3e@xxxxxxxxxxxxxxxxxxxxxxxxx
>
> ==================================================================
> BUG: KASAN: slab-out-of-bounds in vsnprintf+0x1727/0x19a0
> lib/vsprintf.c:2503
> Read of size 8 at addr ffff8880a91c7d00 by task syz-executor.0/9821
>
> CPU: 0 PID: 9821 Comm: syz-executor.0 Not tainted 5.2.0-rc3+ #13
> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
> Google 01/01/2011
> Call Trace:
>
> Allocated by task 1024:
> (stack is not available)
>
> Freed by task 2310999008:
> ------------[ cut here ]------------
> Bad or missing usercopy whitelist? Kernel memory overwrite attempt detected
> to SLAB object 'skbuff_head_cache' (offset 24, size 1)!
> WARNING: CPU: 0 PID: 9821 at mm/usercopy.c:78 usercopy_warn+0xeb/0x110
> mm/usercopy.c:78
> Kernel panic - not syncing: panic_on_warn set ...
> Shutting down cpus with NMI
> Kernel Offset: disabled
>
>
> ---
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