🚨 CRITICAL - Linux kernel OCFS2/DLM out-of-bounds read in dlm_match_regions() (CVE-2026-53309) A critical vulnerability in the Linux kernel’s ocfs2/dlm code affects dlm_match_regions() during region comparison, where it can read past the end of the qr_regions array. The root cause is an off-by-one error (improper bounds checking) where the loop uses "<=" instead of "<", triggering an out-of-bounds read. An attacker can exploit this by causing the DLM region comparison path to execute with crafted region data, typically in environments using OCFS2/DLM (e.g., clustered setups) where the vulnerable code path is reachable. Impact ranges from kernel memory disclosure and potential information leak to kernel instability/denial of service, and in worst cases could aid further exploitation depending on surrounding conditions. 👉 Affected: Linux kernel ocfs2/dlm (versions with dlm_match_regions() using "<=" in qr_regions loop) | Upgrade to a kernel release that includes the fix changing the loop condition to "<"
Post summary
The advisory reports a critical out‑of‑bounds read vulnerability (CVE‑2026‑53309) in Linux kernel ocfs2/dlm, explains the off‑by‑one error, and recommends upgrading to a patched kernel release.
