Description
In the Linux kernel, the following vulnerability has been resolved: s390/cpum_sf: Handle CPU hotplug remove during sampling CPU hotplug remove handling triggers the following function call sequence: CPUHP_AP_PERF_S390_SF_ONLINE --> s390_pmu_sf_offline_cpu() ... CPUHP_AP_PERF_ONLINE --> perf_event_exit_cpu() The s390 CPUMF sampling CPU hotplug handler invokes: s390_pmu_sf_offline_cpu() +--> cpusf_pmu_setup() +--> setup_pmc_cpu() +--> deallocate_buffers() This function de-allocates all sampling data buffers (SDBs) allocated for that CPU at event initialization. It also clears the PMU_F_RESERVED bit. The CPU is gone and can not be sampled. With the event still being active on the removed CPU, the CPU event hotplug support in kernel performance subsystem triggers the following function calls on the removed CPU: perf_event_exit_cpu() +--> perf_event_exit_cpu_context() +--> __perf_event_exit_context() +--> __perf_remove_from_context() +--> event_sched_out() +--> cpumsf_pmu_del() +--> cpumsf_pmu_stop() +--> hw_perf_event_update() to stop and remove the event. During removal of the event, the sampling device driver tries to read out the remaining samples from the sample data buffers (SDBs). But they have already been freed (and may have been re-assigned). This may lead to a use after free situation in which case the samples are most likely invalid. In the best case the memory has not been reassigned and still contains valid data. Remedy this situation and check if the CPU is still in reserved state (bit PMU_F_RESERVED set). In this case the SDBs have not been released an contain valid data. This is always the case when the event is removed (and no CPU hotplug off occured). If the PMU_F_RESERVED bit is not set, the SDB buffers are gone.
Affected products
Version statuses are supplied by the assigning organization. Consult the original record for detailed ranges and platform conditions.
Linux Linux
Default version status: unaffected
e3d617fe6ac7294974fc513dc5e4d8ada8080fd1 to < 238e3af849dfdcb1faed544349f7025e533f9aabaffectede3d617fe6ac7294974fc513dc5e4d8ada8080fd1 to < 99192c735ed4bfdff0d215ec85c8a87a677cb898affectede3d617fe6ac7294974fc513dc5e4d8ada8080fd1 to < 06a92f810df8037ca36157282ddcbefdcaf049b8affectede3d617fe6ac7294974fc513dc5e4d8ada8080fd1 to < b5be6a0bb639d165c8418d8dddd8f322587be8beaffectede3d617fe6ac7294974fc513dc5e4d8ada8080fd1 to < a69752f1e5de817941a2ea0609254f6f25acd274affectede3d617fe6ac7294974fc513dc5e4d8ada8080fd1 to < be54e6e0f93a39a9c00478d70d12956a5f3d5b9baffectede3d617fe6ac7294974fc513dc5e4d8ada8080fd1 to < a0bd7dacbd51c632b8e2c0500b479af564afadf3affected
Linux Linux
Default version status: affected
4.8affected0 to < 4.8unaffected5.4.287 to ≤ 5.4.*unaffected5.10.231 to ≤ 5.10.*unaffected5.15.174 to ≤ 5.15.*unaffected6.1.120 to ≤ 6.1.*unaffected6.6.66 to ≤ 6.6.*unaffected6.12.5 to ≤ 6.12.*unaffected6.13 to ≤ *unaffected
References
- https://git.kernel.org/stable/c/238e3af849dfdcb1faed544349f7025e533f9aab ↗
- https://git.kernel.org/stable/c/99192c735ed4bfdff0d215ec85c8a87a677cb898 ↗
- https://git.kernel.org/stable/c/06a92f810df8037ca36157282ddcbefdcaf049b8 ↗
- https://git.kernel.org/stable/c/b5be6a0bb639d165c8418d8dddd8f322587be8be ↗
- https://git.kernel.org/stable/c/a69752f1e5de817941a2ea0609254f6f25acd274 ↗
- https://git.kernel.org/stable/c/be54e6e0f93a39a9c00478d70d12956a5f3d5b9b ↗
- https://git.kernel.org/stable/c/a0bd7dacbd51c632b8e2c0500b479af564afadf3 ↗
- https://lists.debian.org/debian-lts-announce/2025/03/msg00001.html ↗