CVE-2012-2100: Divide by Zero
First published: Wed Apr 04 2012(Updated: )
Commit 503358ae01b70ce6909d19dd01287093f6b6271c ("ext4: avoid divide by zero when trying to mount a corrupted file system") fixes <a href="https://access.redhat.com/security/cve/CVE-2009-4307">CVE-2009-4307</a> by performing a sanity check on s_log_groups_per_flex, since it can be set to a bogus value by an attacker. More info from Wang Xi: The first commit (503358ae) fixes the division by zero. The fix is not perfect because: 1) Theoretically, a standard-conforming C compiler could generate code that is still vulnerable to division by zero, but I was not aware of any compilers doing that. 2) Logically, we should have groups_per_flex = 2^s_log_groups_per_flex, and the fix doesn't really ensure that. This is obviously not good, but not sure how bad the consequence would be. Introduced by: <a href="http://git.kernel.org/linus/503358ae01b70ce6909d19dd01287093f6b6271c">http://git.kernel.org/linus/503358ae01b70ce6909d19dd01287093f6b6271c</a> Upstream commit: <a href="http://git.kernel.org/linus/d50f2ab6f050311dbf7b8f5501b25f0bf64a439b">http://git.kernel.org/linus/d50f2ab6f050311dbf7b8f5501b25f0bf64a439b</a>
Credit: secalert@redhat.com secalert@redhat.com
| Affected Software | Affected Version | How to fix |
|---|---|---|
| Linux Linux kernel | <=3.2.1 | |
| Linux Linux kernel | =3.2 | |
| debian/linux-2.6 |
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Reference Links
- http://git.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git%3Ba=commit%3Bh=d50f2ab6f050311dbf7b8f5501b25f0bf64a439b
- http://rhn.redhat.com/errata/RHSA-2012-1445.html
- http://rhn.redhat.com/errata/RHSA-2012-1580.html
- http://www.kernel.org/pub/linux/kernel/v3.x/ChangeLog-3.2.2
- http://www.openwall.com/lists/oss-security/2012/04/12/11
- http://www.securityfocus.com/bid/53414
- https://bugzilla.redhat.com/show_bug.cgi?id=809687
- https://github.com/torvalds/linux/commit/d50f2ab6f050311dbf7b8f5501b25f0bf64a439b
- https://launchpad.net/bugs/cve/CVE-2012-2100
- https://access.redhat.com/security/cve/CVE-2009-4307
- http://git.kernel.org/linus/503358ae01b70ce6909d19dd01287093f6b6271c
- http://git.kernel.org/linus/d50f2ab6f050311dbf7b8f5501b25f0bf64a439b
- https://bugzilla.redhat.com/show_bug.cgi/show_bug.cgi?id=809693
- https://lkml.org/lkml/2012/2/20/422
- https://rhn.redhat.com/errata/RHSA-2012-1445.html
- https://rhn.redhat.com/errata/RHSA-2012-1580.html
- https://security-tracker.debian.org/tracker/CVE-2012-2100
- https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2012-2100
- https://nvd.nist.gov/vuln/detail/CVE-2012-2100
- https://ubuntu.com/security/CVE-2012-2100
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