oss-security - CVE Request: some drm overflow checks

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Date: Mon, 21 May 2012 08:38:31 +0200
From: Marcus Meissner <meissner@...e.de>
To: OSS Security List <oss-security@...ts.openwall.com>
Subject: CVE Request: some drm overflow checks

Hi,

spotted in xorls blog, who spotted it in the kernel stable changelog:
https://xorl.wordpress.com/2012/05/17/linux-kernel-drm-intel-i915-multiple-ioctl-integer-overflows/

It has two issues:

1. overflow of cliprect kmalloc as args->num_cliprects is not bounded
  and passed in via a user ioctl.

  Fixed via ed8cd3b2cd61004cab85380c52b1817aca1ca49b in mainline:
  commit ed8cd3b2cd61004cab85380c52b1817aca1ca49b
  Author: Xi Wang <xi.wang@...il.com>
  Date:   Mon Apr 23 04:06:41 2012 -0400

    drm/i915: fix integer overflow in i915_gem_execbuffer2()

    On 32-bit systems, a large args->buffer_count from userspace via ioctl
    may overflow the allocation size, leading to out-of-bounds access.

    This vulnerability was introduced in commit 8408c282 ("drm/i915:
    First try a normal large kmalloc for the temporary exec buffers").


  8408c282 was added Feb 21 2011, and seemingly added during 2.6.38 development.


2. same file, overflow in args->buffer_count.

   Fix is in mainline 44afb3a04391a74309d16180d1e4f8386fdfa745

   commit 44afb3a04391a74309d16180d1e4f8386fdfa745
   Author: Xi Wang <xi.wang@...il.com>
   Date:   Mon Apr 23 04:06:42 2012 -0400

    drm/i915: fix integer overflow in i915_gem_do_execbuffer()

    On 32-bit systems, a large args->num_cliprects from userspace via ioctl
    may overflow the allocation size, leading to out-of-bounds access.

    This vulnerability was introduced in commit 432e58ed ("drm/i915: Avoid
    allocation for execbuffer object list").


   432e58ed was added during 2.6.37 development.


I think it needs 2 CVEs, due to the different kernel versions introducing it.

Ciao, Marcus

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