CVE-2023-54033: bpf: fix a memory leak in the LRU and LRU_PERCPU hash maps

Severity: unknown
Exploited in the wild: not listed in CISA KEV
EPSS: 0.2% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2025-12-24 · updated 2026-06-17

Description

In the Linux kernel, the following vulnerability has been resolved: bpf: fix a memory leak in the LRU and LRU_PERCPU hash maps The LRU and LRU_PERCPU maps allocate a new element on update before locking the target hash table bucket. Right after that the maps try to lock the bucket. If this fails, then maps return -EBUSY to the caller without releasing the allocated element. This makes the element untracked: it doesn't belong to either of free lists, and it doesn't belong to the hash table, so can't be re-used; this eventually leads to the permanent -ENOMEM on LRU map updates, which is unexpected. Fix this by returning the element to the local free list if bucket locking fails.

Affected products

Linux kernel: 5.11 — fixed in 6.4

How to fix

Upgrade to a fixed version: Linux kernel 6.4. Check the vendor advisory for mitigations.

References

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