cve 2025 40081

CVE-2025-40081 is a Linux kernel vulnerability in the ARM Statistical Profiling Extension (SPE) perf driver. It involves a numeric overflow in the PERF_IDX2OFF macro that can miscompute buffer offsets for large AUX buffers (2 GiB or larger), potentially leading to kernel instability. The fix is a one-line cast change that converts the buffer pages count to an unsigned long before the left-shift operation, preventing wraparound. The upstream commit has been backported to multiple stable kernel trees. This tag covers discussions about the vulnerability, its root cause, and the patch applied across Linux stable branches.