CVE-2026-89494

In the Linux kernel, the following vulnerability has been resolved:

ocfs2: validate lengths in dlm_mig_lockres_handler

A node receiving a DLM_MIG_LOCKRES message trusts several fields of the peer-supplied dlm_migratable_lockres without validation. num_locks and lockname_len are bounded only on the sending side, and the message is never checked to actually carry num_locks migratable_lock entries. As a result dlm_process_recovery_data() walks mres->ml[0..num_locks) past the kmalloc(data_len) copy of the message (an out-of-bounds read that ends in a BUG_ON panic), and dlm_init_lockres() copies lockname_len bytes into the fixed 32-byte o2dlm_lockname slab object (a heap out-of-bounds write). Both are reachable by any node in the domain.

Validate these fields right after dlm_grab(), before anything uses them – including the not-joined error path, which already prints mres->lockname with the unbounded lockname_len as a %.*s precision. Reject the message unless lockname_len <= DLM_LOCKID_NAME_MAX, num_locks <= DLM_MAX_MIGRATABLE_LOCKS (the bound the sender already asserts), and the payload is large enough to hold the claimed locks. Conforming recovery and migration messages are unaffected.

Affected Software

References

• https://git.kernel.org/stable/c/0e999d56917f861f97adb961617b1828c9eb4733
• https://git.kernel.org/stable/c/4a5798253212093b9ff7d90c6cfbe348bcda1594
• https://git.kernel.org/stable/c/50c4cc9183e11f83427efbf770f54851f4471c02
• https://git.kernel.org/stable/c/77686fa5bba135252d348e2dacf481fc19f60c41
• https://git.kernel.org/stable/c/a8facb1670b4a0612183198e758d9539ef628ed9
• https://git.kernel.org/stable/c/b54e03d9b3697d25f4a0063cf717d459c5e3ad94
• https://git.kernel.org/stable/c/dce05b17db862f47ff60614017abe639b2e71cad
• https://git.kernel.org/stable/c/f33041906885f96e190cde54e61ddc69de39e3ee