Bug 1411245 (CVE-2015-8963) - CVE-2015-8963 kernel: Race condition on CPU unplug leading to use-after-free
Summary: CVE-2015-8963 kernel: Race condition on CPU unplug leading to use-after-free
Keywords:
Status: CLOSED ERRATA
Alias: CVE-2015-8963
Product: Security Response
Classification: Other
Component: vulnerability
Version: unspecified
Hardware: All
OS: Linux
medium
medium
Target Milestone: ---
Assignee: Red Hat Product Security
QA Contact:
URL:
Whiteboard:
Depends On: 1449476 1449477
Blocks: 1395262
TreeView+ depends on / blocked
 
Reported: 2017-01-09 09:04 UTC by Adam Mariš
Modified: 2021-10-27 10:52 UTC (History)
27 users (show)

Fixed In Version: kernel 4.4
Doc Type: If docs needed, set a value
Doc Text:
Race condition in kernel/events/core.c in the Linux kernel before 4.4 allows local users to gain privileges or cause a denial of service via use-after-free vulnerability by leveraging incorrect handling of an swevent data structure during a CPU unplug operation.
Clone Of:
Environment:
Last Closed: 2021-10-27 10:52:04 UTC
Embargoed:

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Description Adam Mariš 2017-01-09 09:04:20 UTC 
Race condition in kernel/events/core.c in the Linux kernel before 4.4 allows local users to gain privileges or cause a denial of service via use-after-free vulnerability by leveraging incorrect handling of an swevent data structure during a CPU unplug operation.

Removing a CPU is a privileged operation and not possible by normal users.  This flaw should not affect many individuals.

Upstream patch:

https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=12ca6ad2e3a896256f086497a7c7406a547ee373
Comment 2 Wade Mealing 2017-05-10 05:51:21 UTC 
Statement:

This issue affects the Linux kernel shipping with Red Hat Enterprise Linux 6. Future updates for the respective releases may address the issue.

This issue does not not affect Red Hat Enterprise Linux 5, 7, MRG-2 kernels.

This has been rated as having Moderate security impact and is not currently planned to be addressed in future updates of Red Hat Enterprise Linux 5. For additional information, refer to the Red Hat Enterprise Linux Life Cycle: https://access.redhat.com/support/policy/updates/errata/.
Comment 3 Wade Mealing 2017-05-10 05:59:41 UTC 
Mitigation:

A possible mitigation is to only remove CPU's while the system is shut down.  This will prevent local attackers from being able to abuse this flaw.
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