CVE-2025-38055 — perf/x86/intel: Fix segfault with PEBS-via-PT with sample_freq

Affected: Linux

In the Linux kernel, the following vulnerability has been resolved:

perf/x86/intel: Fix segfault with PEBS-via-PT with sample_freq

Currently, using PEBS-via-PT with a sample frequency instead of a sample period, causes a segfault. For example:

BUG: kernel NULL pointer dereference, address: 0000000000000195 <NMI> ? __die_body.cold+0x19/0x27 ? page_fault_oops+0xca/0x290 ? exc_page_fault+0x7e/0x1b0 ? asm_exc_page_fault+0x26/0x30 ? intel_pmu_pebs_event_update_no_drain+0x40/0x60 ? intel_pmu_pebs_event_update_no_drain+0x32/0x60 intel_pmu_drain_pebs_icl+0x333/0x350 handle_pmi_common+0x272/0x3c0 intel_pmu_handle_irq+0x10a/0x2e0 perf_event_nmi_handler+0x2a/0x50

That happens because intel_pmu_pebs_event_update_no_drain() assumes all the pebs_enabled bits represent counter indexes, which is not always the case. In this particular case, bits 60 and 61 are set for PEBS-via-PT purposes.

The behaviour of PEBS-via-PT with sample frequency is questionable because although a PMI is generated (PEBS_PMI_AFTER_EACH_RECORD), the period is not adjusted anyway.

Putting that aside, fix intel_pmu_pebs_event_update_no_drain() by passing the mask of counter bits instead of 'size'. Note, prior to the Fixes commit, 'size' would be limited to the maximum counter index, so the issue was not hit.

USN-7769-1 — linux, linux-aws, linux-gcp, linux-gcp-6.14, linux-oracle, linux-realtime vulnerabilities

Affected: Ubuntu:24.04:LTS: linux-gcp-6.14

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; - PowerPC architecture; - x86 architecture; - Block layer subsystem; - Cryptographic API; - ACPI drivers; - Android drivers; - Bluetooth drivers; - Bus devices; - Clock framework and drivers; - CPU frequency scaling framework; - Hardware crypto device drivers; - DMA engine subsystem; - EDAC drivers; - Arm Firmware Framework for ARMv8-A(FFA); - FPGA Framework; - GPIO subsystem; - GPU drivers; - HID subsystem; - Hardware monitoring drivers; - HW tracing; - InfiniBand drivers; - IOMMU subsystem; - Multiple devices driver; - Media drivers; - VMware VMCI Driver; - MTD block device drivers; - Network drivers; - Mellanox network drivers; - STMicroelectronics network drivers; - NVDIMM (Non-Volatile Memory Device) drivers; - NVME drivers; - NVMEM (Non Volatile Memory) drivers; - PCI subsystem; - Amlogic Meson DDR PMU; - NI-700 PMU driver; - PHY drivers; - Pin controllers subsystem; - x86 platform drivers; - PTP clock framework; - SCSI subsystem; - ASPEED SoC drivers; - SPI subsystem; - TCM subsystem; - Thunderbolt and USB4 drivers; - TTY drivers; - UFS subsystem; - USB core drivers; - USB Gadget drivers; - Renesas USBHS Controller drivers; - USB Type-C Port Controller Manager driver;…

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CVE-2025-38055 — perf/x86/intel: Fix segfault with PEBS-via-PT with sample_freq

USN-7769-1 — linux, linux-aws, linux-gcp, linux-gcp-6.14, linux-oracle, linux-realtime vulnerabilities