oss-security - Re: CVE request: glibc formatted printing vulnerabilities

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Date: Wed, 11 Jul 2012 11:18:27 -0600
From: Kurt Seifried <kseifried@...hat.com>
To: oss-security@...ts.openwall.com
CC: Stefan Cornelius <scorneli@...hat.com>
Subject: Re: CVE request: glibc formatted printing vulnerabilities

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On 07/11/2012 04:32 AM, Stefan Cornelius wrote:
> Hi,
> 
> there are further vulnerabilities in glibc's formatted printing 
> functionality.
> 
> 1) It was discovered that the formatted printing functionality in
> glibc did not properly honor the size of a structure when
> calculating the amount of memory to allocate. A remote attacker
> could provide a specially crafted sequence of format specifiers,
> leading to an undersized buffer allocation and subsequent stack
> corruption, resulting in a crash or, potentially, FORTIFY_SOURCE
> format string protection mechanism bypass, when processed.
> 
> References: http://sourceware.org/bugzilla/show_bug.cgi?id=12445 
> http://sourceware.org/git/?p=glibc.git;a=commitdiff;h=84a4211850e3d23a9d3a4f3b294752a3b30bc0ff
>
> 
https://bugzilla.redhat.com/show_bug.cgi?id=833703

Please use CVE-2012-3404 for this issue.

> 2) It was discovered that the formatted printing functionality in
> glibc used extend_alloca() incorrectly. "nspecs_max" is incorrectly
> passed to extend_alloca, which modifies the value in "nspecs_max"
> when allocating the memory. A remote attacker could provide a
> specially crafted sequence of format specifiers, leading to a
> desynchronization within the buffer size handling, resulting in the
> use of uninitialized memory or, potentially, FORTIFY_SOURCE format
> string protection mechanism bypass, when processed.
> 
> References: http://sourceware.org/bugzilla/show_bug.cgi?id=13446 
> http://sourceware.org/git/?p=glibc.git;a=commitdiff;h=a4647e727a2a52e1259474c13f4b13288938bed4
>
> 
https://bugzilla.redhat.com/show_bug.cgi?id=833704
> 
> It seems like 1) and 2) were introduced by the following commit: 
> http://sourceware.org/git/?p=glibc.git;a=commitdiff;h=1d498daa95384e5c9ad5bcb35e7a996e5869ac39

Please
> 
use CVE-2012-3405 for this issue.

> 3) It was discovered that the formatted printing functionality in
> glibc did not properly restrict the use of alloca(). A remote
> attacker could provide a specially crafted sequence of format
> specifiers, leading to a crash or, potentially, FORTIFY_SOURCE
> format string protection mechanism bypass, when processed.
> 
> References: https://bugzilla.redhat.com/show_bug.cgi?id=826943
> 
> Red Hat patch backports/testcases for RHEL6 that include a patch
> for this: 
> https://bugzilla.redhat.com/attachment.cgi?id=594722&action=diff
> 
> Red Hat patch backport/testcase for RHEL5 (older glibc versions) 
> https://bugzilla.redhat.com/attachment.cgi?id=594727&action=diff

Please use CVE-2012-3406 for this issue.

> 
> Thanks in advance and kind regards
> 


- -- 
Kurt Seifried Red Hat Security Response Team (SRT)
PGP: 0x5E267993 A90B F995 7350 148F 66BF 7554 160D 4553 5E26 7993



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