Executive brief
A vulnerability in the Linux kernel's performance monitoring subsystem for AMD processors could cause a system crash. The issue occurs when the system attempts to check security permissions during a high-priority hardware interrupt, which is a technically 'unsafe' operation for the operating system. An exploit could lead to a total system failure or denial of service.
Technical details
The vulnerability exists in the AMD IBS (Instruction Based Sampling) driver within the Linux kernel's perf subsystem. The root cause is the unsafe invocation of perf_allow_kernel() from within an NMI (Non-Maskable Interrupt) handler. NMIs have strict execution constraints, and calling functions that may sleep or perform complex locking can result in kernel panics or 'fatal' system states. An attacker with local access to performance monitoring tools could trigger this condition. The fix involves caching the permission bit during event initialization (perf_ibs_init) and checking the cached flag in the NMI handler instead of calling the function directly.
Affected products
- Linux Linux Kernel 6.14, 6.18.33, 7.0.10
Timeline
- 2026-02-16: other: Initial patch authored
- 2026-06-24: disclosed: CVE published