Bug 285991 (CVE-2007-4730) - CVE-2007-4730 X.org composite extension buffer overflow
Summary: CVE-2007-4730 X.org composite extension buffer overflow
Alias: CVE-2007-4730
Product: Security Response
Classification: Other
Component: vulnerability
Version: unspecified
Hardware: All
OS: Linux
Target Milestone: ---
Assignee: Red Hat Product Security
QA Contact:
URL: http://bugs.freedesktop.org/show_bug....
Depends On: 286051 286061 286071 286081 286091 286101 286111
TreeView+ depends on / blocked
Reported: 2007-09-11 14:01 UTC by Josh Bressers
Modified: 2021-11-12 19:43 UTC (History)
2 users (show)

Fixed In Version:
Doc Type: Bug Fix
Doc Text:
Clone Of:
Last Closed: 2007-10-26 09:16:28 UTC

Attachments (Terms of Use)

System ID Private Priority Status Summary Last Updated
Red Hat Product Errata RHSA-2007:0898 0 normal SHIPPED_LIVE Moderate: xorg-x11 security update 2008-01-07 19:28:35 UTC

Description Josh Bressers 2007-09-11 14:01:10 UTC
A buffer overflow flaw has been found in the X.org composite extension.  The
upstream bug has more details:


By running a server at depth 16, it becomes possible for a local user to
overflow a buffer by creating a window with depth 32, then resizing it.

Comment 2 Søren Sandmann Pedersen 2007-09-11 19:15:15 UTC
FC6, F7, Fdevel, and rhels 5.0.z, 5.1 are not vulnerable because of this patch:

localhost:~/vertigo/rpms/xorg-x11-server/RHEL-5% cat
Disable backfilling of windows created with bg=none, which otherwise
would force a framebuffer readback.

--- ./composite/compalloc.c.spiffiffity 2006-03-13 16:59:55.000000000 -0500
+++ ./composite/compalloc.c     2006-04-12 16:37:50.000000000 -0400
@@ -478,6 +478,7 @@
      * Copy bits from the parent into the new pixmap so that it will
      * have "reasonable" contents in case for background None areas.
+#if 0
     if (pGC)
        XID val = IncludeInferiors;
@@ -492,6 +493,7 @@
                               w, h, 0, 0);
        FreeScratchGC (pGC);
     return pPixmap;

Comment 3 Josh Bressers 2007-09-18 11:55:22 UTC
We are changing the severity here to moderate. Here is some additional
information provided by Adam Jackson:

- the Composite extension is not enabled by default in RHEL4, so the user
  would have had to go out of their way to turn it on.
- we don't ship any compositing manager in RHEL4, so they'd need to have
  installed one.
- the exploit requires the ability to authenticate to the X server, so the
  attacker would need to have already gained rights equivalent to the user.

Comment 4 Tomas Hoger 2007-10-26 09:16:28 UTC
For Red Hat Enterprise Linux 4, this issue was addressed in RHSA-2007:0898:


Red Hat Enterprise Linux 5 and current versions of Fedora were not affected as
described in comment #2.

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