Re: [ 0.003333] BUG: KASAN: use-after-scope in console_unlock+0x605/0xcc0

Andrey Ryabinin
2017-11-30T13:04:07Z

On 11/30/2017 11:29 AM, 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.

.config has CONFIG_GCC_PLUGIN_STRUCTLEAK_BYREF_ALL=y
It's known to cause use-after-scope problems, so printk/console code is likely
has nothing to do with the bug.

>>
>> 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).

I suspect you don't have gcc 7. That's is requirement for use-after-scope.

> -ss
>