linux-kernel - Re: [PATCH 1/2] ARM: check stack pointer in get

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Message-ID: <20131205113348.GE4360@n2100.arm.linux.org.uk>
Date:	Thu, 5 Dec 2013 11:33:48 +0000
From:	Russell King - ARM Linux <linux@....linux.org.uk>
To:	Konstantin Khlebnikov <k.khlebnikov@...sung.com>
Cc:	linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
	Will Deacon <will.deacon@....com>,
	Vyacheslav Tyrtov <v.tyrtov@...sung.com>
Subject: Re: [PATCH 1/2] ARM: check stack pointer in get_wchan

On Thu, Dec 05, 2013 at 12:34:24PM +0400, Konstantin Khlebnikov wrote:
> get_wchan() is lockless. Task may wakeup at any time and change its own stack,
> thus each next stack frame may be overwritten and filled with random stuff.
> 
> /proc/$pid/stack interface had been disabled for non-current tasks, see [1]
> But 'wchan' still allows to trigger stack frame unwinding on volatile stack.
> 
> This patch fixes oops in unwind_frame() by adding stack pointer validation on
> each step (as x86 code do), unwind_frame() already checks frame pointer.
> 
> Also I've found another report of this oops on stackoverflow (irony).

Your two patches look fine to me.  Please put them in the patch system
and we'll get them merged - I think they should also be merged into stable
trees too - it looks like this goes all the way back to 2.6.30 kernels.

Thanks.
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