DEBIAN-CVE-2026-99125: Debian/linux vulnerability
In the Linux kernel, the following vulnerability has been resolved: s390/pai: Handle multiple PMU stop callback invocations Handle the following scenario: The kernel protects itself against a very high sampling load and throttles the sampling using: perfeventthrottle() --> PMU->stop() Shortly later the scheduler may terminate the task and removes it from the CPU. It again calls PMU->stop() which results in two invocations of PMU->stop() called back to back. Protect against this and check the PERFHESSTOPPED bit on function entry. If it is already set return. Clear bit PERFHESSTOPPED in PMU->start(). Prohibit ioctl(fd, PERFEVENTIOCPERIOD, ...) call for this event. It sets perfevent::eventlimit to a positive value and causes perfeventoverflow() to invoke paistop() call back function when perfevent::eventlimit hits zero. This is not supported because the sample events CRYPTOALL and NNPAALL are only taken at schedule out of a task. Use listforeachentrysafe() for safe iteration over syswidelist in paihavesamples().
Affected Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
- Compensating control
In PMU->start(), check PERF_HES_STOPPED on function entry; if it is already set, return, otherwise clear PERF_HES_STOPPED.
- Compensating control
Prohibit ioctl(fd, PERF_EVENT_IOC_PERIOD, ...) for this event.
- Compensating control
Use list_for_each_entry_safe() when iterating over syswide_list in pai_have_samples().