CVE-2021-20265

A flaw was found in the way memory resources were freed in the unix_stream_recvmsg function in the Linux kernel when a signal was pending. This flaw allows an unprivileged local user to crash the system by exhausting available memory. The highest threat from this vulnerability is to system availability.

Weakness

The product does not properly control the allocation and maintenance of a limited resource.

Affected Software

Potential Mitigations

• Mitigation of resource exhaustion attacks requires that the target system either:

• The first of these solutions is an issue in itself though, since it may allow attackers to prevent the use of the system by a particular valid user. If the attacker impersonates the valid user, they may be able to prevent the user from accessing the server in question.

• The second solution is simply difficult to effectively institute – and even when properly done, it does not provide a full solution. It simply makes the attack require more resources on the part of the attacker.

Related Attack Patterns

• https://cwe.mitre.org/data/definitions/147.html
• https://cwe.mitre.org/data/definitions/227.html
• https://cwe.mitre.org/data/definitions/492.html

References

• https://bugzilla.redhat.com/show_bug.cgi?id=1908827
• https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=fa0dc04df259ba2df3ce1920e9690c7842f8fa4b
• https://www.oracle.com/security-alerts/cpuoct2021.html
• https://bugzilla.redhat.com/show_bug.cgi?id=1908827
• https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=fa0dc04df259ba2df3ce1920e9690c7842f8fa4b
• https://www.oracle.com/security-alerts/cpuoct2021.html