Re: Out-of-bounds access in get_wchan (arch/x86/kernel/process_64.c)

[Andi Kleen]

> Indeed, get_wchan ensures that fp<stack+THREAD_SIZE, but then dereferences fp+8:
> 
> 434                 if (fp < (unsigned long)stack ||
> 435                     fp >= (unsigned long)stack+THREAD_SIZE)
> 436                         return 0;
> 437                 ip = *(u64 *)(fp+8);
> 
> It must check that fp+8<stack+THREAD_SIZE.
> As far as I see, the bug can lead to garbage return values or in the
> worst case to crash.

Thanks for the report.

The change looks good to me. Can you please submit a formal signed off patch
to x86@xxxxxxxxxx ?

-Andi


-- 
ak@xxxxxxxxxxxxxxx -- Speaking for myself only
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