CVE-2024-57849 — s390/cpum_sf: Handle CPU hotplug remove during sampling

Affected: Linux

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 in…

USN-7379-1 — linux, linux-aws, linux-azure, linux-gcp, linux-hwe-6.11, linux-oracle, linux-realtime vulnerabilities

Affected: Ubuntu:24.04:LTS: linux-hwe-6.11

Several security issues were discovered in the Linux kernel. An attacker could possibly use these to compromise the system. This update corrects flaws in the following subsystems: - ARM64 architecture; - MIPS architecture; - PowerPC architecture; - RISC-V architecture; - S390 architecture; - x86 architecture; - Block layer subsystem; - Compute Acceleration Framework; - ACPI drivers; - Drivers core; - Ublk userspace block driver; - Virtio block driver; - Bluetooth drivers; - Buffer Sharing and Synchronization framework; - DMA engine subsystem; - EFI core; - GPIO subsystem; - GPU drivers; - HID subsystem; - Microsoft Hyper-V drivers; - Hardware monitoring drivers; - I3C subsystem; - IIO ADC drivers; - IIO subsystem; - InfiniBand drivers; - IOMMU subsystem; - LED subsystem; - Multiple devices driver; - Media drivers; - Microchip PCI driver; - MTD block device drivers; - Network drivers; - Mellanox network drivers; - STMicroelectronics network drivers; - NVME drivers; - PCI subsystem; - PHY drivers; - Pin controllers subsystem; - x86 platform drivers; - i.MX PM domains; - Power supply drivers; - Voltage and Current Regulator drivers; - SCSI subsystem; - i.MX SoC drivers; - SPI subsystem; - UFS subsystem; - USB Gadget drivers; - TDX Guest driver; - AFS file system; - BTRFS file system; - Ceph distributed file system; - File systems infrastructure; - F2FS file system; - JFFS…

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CVE-2024-57849 — s390/cpum_sf: Handle CPU hotplug remove during sampling

USN-7379-1 — linux, linux-aws, linux-azure, linux-gcp, linux-hwe-6.11, linux-oracle, linux-realtime vulnerabilities