CVE-2012-2121
First published: Thu Apr 19 2012(Updated: )
KVM uses memory slots to track and map guest regions of memory. When device assignment is used, the pages backing these slots are pinned in memory using get_user_pages and mapped into the iommu. The problem is that when a memory slot is destroyed the pages for the associated memory slot are neither unpinned nor unmapped from the iommu. The problem is that those pages are now never unpinned and continue to have an increased reference count. This is therefore a potential page leak from the kvm kernel module. On Red Hat Enterprise Linux, local user with ability to assign device (with access to PCI sysfs files for a device) could use this flaw to DoS the system. With upstream qemu-kvm/kvm privileged guest user that could hotunplug and then hotplug back certain devices could potentially use this flaw to DoS the host. Upstream fixes: <a href="http://git.kernel.org/?p=virt/kvm/kvm.git;a=commit;h=32f6daad4651a748a58a3ab6da0611862175722f">http://git.kernel.org/?p=virt/kvm/kvm.git;a=commit;h=32f6daad4651a748a58a3ab6da0611862175722f</a> <a href="http://git.kernel.org/?p=virt/kvm/kvm.git;a=commit;h=21a1416a1c945c5aeaeaf791b63c64926018eb77">http://git.kernel.org/?p=virt/kvm/kvm.git;a=commit;h=21a1416a1c945c5aeaeaf791b63c64926018eb77</a> References: <a href="https://lkml.org/lkml/2012/4/11/248">https://lkml.org/lkml/2012/4/11/248</a>
Credit: secalert@redhat.com
| Affected Software | Affected Version | How to fix |
|---|---|---|
| debian/linux-2.6 | ||
| Linux kernel | <=3.3.3 |
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Reference Links
- http://rhn.redhat.com/errata/RHSA-2012-0676.html
- http://rhn.redhat.com/errata/RHSA-2012-0743.html
- http://secunia.com/advisories/50732
- http://www.kernel.org/pub/linux/kernel/v3.x/ChangeLog-3.3.4
- http://www.openwall.com/lists/oss-security/2012/04/19/16
- http://www.securitytracker.com/id?1027083
- http://www.ubuntu.com/usn/USN-1577-1
- http://www.ubuntu.com/usn/USN-2036-1
- http://www.ubuntu.com/usn/USN-2037-1
- https://bugzilla.redhat.com/show_bug.cgi?id=814149
- https://github.com/torvalds/linux/commit/09ca8e1173bcb12e2a449698c9ae3b86a8a10195
- https://launchpad.net/bugs/cve/CVE-2012-2121
- http://git.kernel.org/?p=virt/kvm/kvm.git;a=commit;h=32f6daad4651a748a58a3ab6da0611862175722f
- http://git.kernel.org/?p=virt/kvm/kvm.git;a=commit;h=21a1416a1c945c5aeaeaf791b63c64926018eb77
- https://lkml.org/lkml/2012/4/11/248
- https://bugzilla.redhat.com/show_bug.cgi/show_bug.cgi?id=814155
- https://rhn.redhat.com/errata/RHSA-2012-0676.html
- https://rhn.redhat.com/errata/RHSA-2012-0743.html
- https://security-tracker.debian.org/tracker/CVE-2012-2121
- https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2012-2121
- https://nvd.nist.gov/vuln/detail/CVE-2012-2121
- https://ubuntu.com/security/CVE-2012-2121
Frequently Asked Questions
What is the severity of CVE-2012-2121?
CVE-2012-2121 has a medium to high severity rating due to potential memory corruption that could be exploited.
What software is affected by CVE-2012-2121?
CVE-2012-2121 affects various versions of the Linux Kernel up to 3.3.3 and the linux-2.6 package on Debian.
How do I fix CVE-2012-2121?
To fix CVE-2012-2121, update your Linux Kernel to a version that has patched this vulnerability.
What are the implications of CVE-2012-2121?
Exploitation of CVE-2012-2121 may allow attackers to perform unauthorized actions through memory corruption.
Is CVE-2012-2121 related to virtualization?
Yes, CVE-2012-2121 is related to the KVM (Kernel-based Virtual Machine) and impacts guest memory management.
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