Linux Kernel Simple Ring Buffer Reader Swap Vulnerability in Linux

CVE-2026-89748

What is CVE-2026-89748?

A vulnerability in the Linux kernel related to the simple ring buffer reader swap can lead to improper bookkeeping following unsuccessful attempts to replace links. The mechanism starts with a retry limit of 8, decrementing with each failed link replacement. If the final attempt succeeds, it incorrectly ends with the retry counter at zero while a failure leaves it at a negative count. This mismanagement results in erroneous updates of the head and reader pointers, potentially corrupting the ring buffer. The issue has been mitigated by adjusting the check for negative counters, ensuring only those are treated as exhaustion to return the proper error signaling.

References