CVE-2012-2133: Use After Free
Last updated 24 July 2024
Other sources
There is a use after free bug in the kernel hugetlb code. The bug can allow an authenticated, unprivileged local attacker to crash the system (and possibly gain higher privileges) if huge pages are enabled in the system.
A fix has been committed to upstream, commit 90481622d75715bfcb68501280a917dbfe516029 "hugepages: fix use after free bug in "quota" handling"
Version-Release number of selected component (if applicable): The bug exists in kernel versions 2.6.24 and above.
How reproducible: The attached tarball includes an example code which utilizes a fuse mount with ODIRECT flag to reproduce the issue. The code will work only on kernels 2.6.32 and above since it uses the new "anonymous mapping" API for getting huge pages. Similar reproduction is possible when using the shmem API or the hugetlbfs API. Stock kernel might not crash, debug kernel will detect the corruption and kill the process.
Steps to Reproduce: 1. Untar the attached file 2. Run runtest.sh. The fuse-devel package and sudo rights are required for the fuse mount. Sudo rights are also required for enabling huge pages. 3. Observe the kernel crash when running debug kernel. Normal kernels will (usually) not crash, as the slab allocator will not return the memory blocks to the system general pool for a while.
Actual results: A general protection fault message is printed, and the server is frozen.
Expected results: The process should exit without the kernel crashing.
Additional info: Verified on RHEL 6.0 with Dell PowerEdge 2950, should exist also on RHEL 6.2 and 6.1.
Upstream commit: http://git.kernel.org/linus/90481622d75715bfcb68501280a917dbfe516029
Acknowledgements:
Red Hat would like to thank Shachar Raindel for reporting this issue.
— Red Hat
Use-after-free vulnerability in the Linux kernel before 3.3.6, when huge pages are enabled, allows local users to cause a denial of service (system crash) or possibly gain privileges by interacting with a hugetlbfs filesystem, as demonstrated by a umount operation that triggers improper handling of quota data.
— Launchpad
Affected Software
Remediation
Event History
Frequently Asked Questions
What is the severity of CVE-2012-2133?
CVE-2012-2133 has a severity rating that indicates it can allow an authenticated, unprivileged local attacker to crash the system or gain heightened privileges when huge pages are enabled.
How do I fix CVE-2012-2133?
To fix CVE-2012-2133, ensure you apply the latest patches from your Linux distribution that address this vulnerability.
Which versions of the Linux kernel are affected by CVE-2012-2133?
CVE-2012-2133 affects Linux kernel versions up to and including 3.3.5.
What exploitability concerns are associated with CVE-2012-2133?
CVE-2012-2133 poses a risk as it allows a local attacker to exploit the vulnerability, potentially leading to system crashes or privilege escalation.
Is CVE-2012-2133 present in all Linux distributions?
CVE-2012-2133 may be present in Linux distributions that utilize the vulnerable versions of the Linux kernel, specifically those using huge pages.