From: Michael Ellerman <michael@ellerman.id.au>
To: Michael Neuling <mikey@neuling.org>
Cc: Paul Mackerras <paulus@samba.org>,
anton@samba.org, Linux PPC dev <linuxppc-dev@ozlabs.org>
Subject: Re: [PATCH] powerpc: Fix bad stack check in exception entry
Date: Wed, 18 Dec 2013 12:55:50 +1100 [thread overview]
Message-ID: <1387331750.19507.3.camel@concordia> (raw)
In-Reply-To: <15350.1387167163@ale.ozlabs.ibm.com>
On Mon, 2013-12-16 at 15:12 +1100, Michael Neuling wrote:
> In EXCEPTION_PROLOG_COMMON() we check to see if the stack pointer (r1)
> is valid when coming from the kernel. If it's not valid, we die but
> with a nice oops message.
>
> Currently we allocate a stack frame (subtract INT_FRAME_SIZE) before we
> check to see if the stack pointer is negative. Unfortunately, this
> won't detect a bad stack where r1 is less than INT_FRAME_SIZE.
The key detail being that we *expect* a negative value, because kernel
addresses (0xc000000000000000) are negative.
cheers
prev parent reply other threads:[~2013-12-18 1:55 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-12-16 4:12 [PATCH] powerpc: Fix bad stack check in exception entry Michael Neuling
2013-12-18 1:55 ` Michael Ellerman [this message]
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