From: david mosberger <dmosberger@gmail.com>
To: linux-ia64@vger.kernel.org
Subject: Re: [patch] make exception handler in copy_user more robust
Date: Wed, 07 Sep 2005 01:10:40 +0000 [thread overview]
Message-ID: <ed5aea4305090618101093a1bd@mail.gmail.com> (raw)
In-Reply-To: <200509062306.j86N64g19803@unix-os.sc.intel.com>
Since we no longer support GCC 2.x, could that code perhaps be
simplified by taking advantage of tags?
--david
On 9/6/05, Chen, Kenneth W <kenneth.w.chen@intel.com> wrote:
> The exception handler in copy user always expects fault occurs only on
> user space address and the fall back recovery code is written with that
> very assumption in mind. Recent source code inspection revealed that
> while it worked splendid and to the expectation under normal circumstances,
> It broke down under unexpected condition where some address calculation
> might go outside the legal address range the original copy_user was
> called for. This patch is to make copy_user exception handler more robust
> and to prevent potential memory corruption.
>
>
> Signed-off-by: Ken Chen <kenneth.w.chen@intel.com>
>
>
> --- linux-2.6.13/arch/ia64/lib/memcpy_mck.S.orig 2005-09-06 15:15:29.560795174 -0700
> +++ linux-2.6.13/arch/ia64/lib/memcpy_mck.S 2005-09-06 15:21:46.798095240 -0700
> @@ -625,8 +625,11 @@ EK(.ex_handler, (p17) st8 [dst1]=r39,8)
> clrrrb
> ;;
> alloc saved_pfs_stack=ar.pfs,3,3,3,0
> + cmp.lt p8,p0=A,r0
> sub B = dst0, saved_in0 // how many byte copied so far
> ;;
> +(p8) mov A = 0; // A shouldn't be negative, cap it
> + ;;
> sub C = A, B
> sub D = saved_in2, A
> ;;
>
> -
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--
Mosberger Consulting LLC, voice/fax: 510-744-9372,
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35706 Runckel Lane, Fremont, CA 94536
next prev parent reply other threads:[~2005-09-07 1:10 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2005-09-06 23:05 [patch] make exception handler in copy_user more robust Chen, Kenneth W
2005-09-07 1:10 ` david mosberger [this message]
2005-09-07 1:49 ` Chen, Kenneth W
2005-09-07 2:07 ` david mosberger
2005-09-07 2:11 ` Chen, Kenneth W
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