CVE-2022-49080: mm/mempolicy: fix mpol_new leak in shared_policy_replace

Severity: medium (CVSS 5.5 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.3% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2025-02-26 · updated 2026-06-17
Weakness: CWE-401

Description

In the Linux kernel, the following vulnerability has been resolved: mm/mempolicy: fix mpol_new leak in shared_policy_replace If mpol_new is allocated but not used in restart loop, mpol_new will be freed via mpol_put before returning to the caller. But refcnt is not initialized yet, so mpol_put could not do the right things and might leak the unused mpol_new. This would happen if mempolicy was updated on the shared shmem file while the sp->lock has been dropped during the memory allocation. This issue could be triggered easily with the below code snippet if there are many processes doing the below work at the same time: shmid = shmget((key_t)5566, 1024 * PAGE_SIZE, 0666|IPC_CREAT); shm = shmat(shmid, 0, 0); loop many times { mbind(shm, 1024 * PAGE_SIZE, MPOL_LOCAL, mask, maxnode, 0); mbind(shm + 128 * PAGE_SIZE, 128 * PAGE_SIZE, MPOL_DEFAULT, mask, maxnode, 0); }

Affected products

Linux kernel: from 3.8.1 before 4.9.311; from 4.10 before 4.14.276; from 4.15 before 4.19.238; from 4.20 before 5.4.189; from 5.5 before 5.10.111; from 5.11 before 5.15.34 — fixed in 4.14.276, 4.19.238, 4.9.311, 5.10.111, 5.15.34, 5.16.20

How to fix

Upgrade to a fixed version: Linux kernel 4.14.276, 4.19.238, 4.9.311, 5.10.111. Check the vendor advisory for mitigations.

References

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