linux-kernel - Re: [ 0.003333] BUG: KASAN: use-after-scope in console

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Date:   Thu, 30 Nov 2017 22:30:06 +0800
From:   Fengguang Wu <fengguang.wu@...el.com>
To:     Sergey Senozhatsky <sergey.senozhatsky.work@...il.com>
Cc:     Dmitry Vyukov <dvyukov@...gle.com>,
        LKML <linux-kernel@...r.kernel.org>,
        Petr Mladek <pmladek@...e.com>,
        Sergey Senozhatsky <sergey.senozhatsky@...il.com>,
        Steven Rostedt <rostedt@...dmis.org>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Ingo Molnar <mingo@...nel.org>,
        Aleksey Makarov <aleksey.makarov@...aro.org>,
        Nicolas Pitre <nicolas.pitre@...aro.org>,
        Nikitas Angelinas <nikitas.angelinas@...il.com>,
        LKP <lkp@...org>, kasan-dev <kasan-dev@...glegroups.com>
Subject: Re: [ 0.003333] BUG: KASAN: use-after-scope in
 console_unlock+0x605/0xcc0

On Thu, Nov 30, 2017 at 05:29:09PM +0900, Sergey Senozhatsky wrote:
>On (11/30/17 09:16), Dmitry Vyukov wrote:
>[..]
>> > to be honest, this backtrace hardly makes any sense to me.
>> >
>> > vprintk_emit()
>> >  reserve_standard_io_resources()
>> >   __flush_tlb_all()
>> >    vprintk_emit()
>> >     __down_trylock_console_sem()
>> >      wake_up_klogd()
>> >       console_unlock()
>> >
>> > I need some help here.
>>
>>
>> You can try dirty patch from here:
>> https://groups.google.com/d/msg/kasan-dev/iDb5bhcMBT0/55QzwWaHAwAJ
>> It should make KASAN print the exact variable name and frame where it
>> was allocated.
>
>would be good if Fengguang can try this out. I can't reproduce the
>problem on my x86 box (linux-next and Linus's trees both work fine
>for me with KASAN + lockdep + TRACE_IRQ).

Attached is the dmesg with Dmitry's patch. The new output is:

[    0.003333] frame offset: 32
[    0.003333] desc: '2 32 4 3 __u 96 8 3 __u '
[    0.003333] func: console_unlock+0x0/0xcc0

Thanks,
Fengguang

Download attachment "dmesg.xz" of type "application/x-xz" (7052 bytes)