CVE-2024-50271 signal: restore the override_rlimit logic
A regression in Linux kernel signal handling causes crashes in applications like Java when resource limits are reached, requiring a patch to restore correct behavior.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2024-50271?
CVE-2024-50271 is a medium-severity denial of service vulnerability in Linux kernel, published on 19 Nov 2024. It can only be exploited from the same machine or local network, with no action from the victim.
Official description
In the Linux kernel, the following vulnerability has been resolved:
signal: restore the override_rlimit logic
Prior to commit d64696905554 ("Reimplement RLIMIT_SIGPENDING on top of ucounts") UCOUNT_RLIMIT_SIGPENDING rlimit was not enforced for a class of signals. However now it's enforced unconditionally, even if override_rlimit is set. This behavior change caused production issues.
For example, if the limit is reached and a process receives a SIGSEGV signal, sigqueue_alloc fails to allocate the necessary resources for the signal delivery, preventing the signal from being delivered with siginfo. This prevents the process from correctly identifying the fault address and handling the error. From the user-space perspective, applications are unaware that the limit has been reached and that the siginfo is effectively 'corrupted'. This can lead to unpredictable behavior and crashes, as we observed with java applications.
Fix this by passing override_rlimit into inc_rlimit_get_ucounts() and skip the comparison to max there if override_rlimit is set. This effectively restores the old behavior.
Weakness: CWE-770
Which versions are affected by CVE-2024-50271?
It affects 1 product.
Products include Linux kernel.
How do I fix CVE-2024-50271?
Apply the vendor's patch.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
Is CVE-2024-50271 being exploited?
There is no known exploitation of CVE-2024-50271 in the wild and no public exploit code.
Other vulnerabilities in Linux kernel
Sources
Also known as AZL-53495, AZL-53787, BELL-CVE-2024-50271, DEBIAN-CVE-2024-50271, GHSA-328f-543x-9jvg, ROOT-OS-UBUNTU-2204-CVE-2024-50271 and 1 more.