CVE-2021-4154

A use-after-free flaw was found in cgroup1_parse_param in kernel/cgroup/cgroup-v1.c in the Linux kernels cgroup v1 parser. A local attacker with a user privilege could cause a privilege escalation by exploiting the fsconfig syscall parameter leading to a container breakout and a denial of service on the system.

Weakness

The product reuses or references memory after it has been freed. At some point afterward, the memory may be allocated again and saved in another pointer, while the original pointer references a location somewhere within the new allocation. Any operations using the original pointer are no longer valid because the memory “belongs” to the code that operates on the new pointer.

Affected Software

Potential Mitigations

References

• https://bugzilla.redhat.com/show_bug.cgi?id=2034514
• https://cloud.google.com/anthos/clusters/docs/security-bulletins#gcp-2022-002
• https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=3b0462726e7ef281c35a7a4ae33e93ee2bc9975b
• https://security.netapp.com/advisory/ntap-20220225-0004/
• https://bugzilla.redhat.com/show_bug.cgi?id=2034514
• https://cloud.google.com/anthos/clusters/docs/security-bulletins#gcp-2022-002
• https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=3b0462726e7ef281c35a7a4ae33e93ee2bc9975b
• https://security.netapp.com/advisory/ntap-20220225-0004/