CVE-2026-98551

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

perf/core: Fill branch entries with a single assignment

perf_clear_branch_entry_bitfields() clears the bitfields of struct perf_branch_entry one by one and leaves from/to alone, since callers overwrite those straight away. The list has to be kept in sync with the struct by hand and has already fallen behind: new_type and priv were added to perf_branch_entry and never added here.

Only BRBE writes those two, and neither for every record. brbe_set_perf_entry_type() leaves new_type alone for a branch type it does not recognise, and priv is not set for source-only records. arm_pmuv3.c allocates the per-CPU branch stack with kmalloc(), so such a record reaches userspace with whatever the slot held: uninitialised kmalloc() data on the first pass over the buffer, the previous record's values after that. Nothing under arch/x86/events/ writes either field, so only arm64 is affected.

Assign the whole entry at each site instead. Everything not named is then zero, and there is no list to keep in sync. The bitfields add up to exactly 64 bits, so the struct has no padding to leave undefined.

perf_clear_branch_entry_bitfields() has no callers left, so remove it. perf_entry_from_brbe_regset() assigns an empty literal instead, since it fills from/to conditionally. PERF_BR_SPEC_NA is 0, so dropping the explicit spec assignment changes nothing.

In the Linux kernel, the following vulnerability has been resolved: perf/core: Fill branch entries with a single assignment perf_clear_branch_entry_bitfields() clears the bitfields of struct perf_branch_entry one by one and leaves from/to alone, since callers overwrite those straight away. The list has to be kept in sync with the struct by hand and has already fallen behind: new_type and priv were added to perf_branch_entry and never added here. Only BRBE writes those two, and neither for every record. brbe_set_perf_entry_type() leaves new_type alone for a branch type it does not recognise, and priv is not set for source-only records. arm_pmuv3.c allocates the per-CPU branch stack with kmalloc(), so such a record reaches userspace with whatever the slot held: uninitialised kmalloc() data on the first pass over the buffer, the previous record's values after that. Nothing under arch/x86/events/ writes either field, so only arm64 is affected. Assign the whole entry at each site instead. Everything not named is then zero, and there is no list to keep in sync. The bitfields add up to exactly 64 bits, so the struct has no padding to leave undefined. perf_clear_branch_entry_bitfields() has no callers left, so remove it. perf_entry_from_brbe_regset() assigns an empty literal instead, since it fills from/to conditionally. PERF_BR_SPEC_NA is 0, so dropping the explicit spec assignment changes nothing.

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:

• USB Gadget drivers;
• Memory management;
• Multiple devices driver;
• ARM64 architecture;
• EROFS file system;
• Networking core;
• eXpress Data Path;
• ARM32 architecture;
• M68K architecture;
• MIPS architecture;
• OpenRISC architecture;
• PA-RISC architecture;
• PowerPC architecture;
• RISC-V architecture;
• S390 architecture;
• User-Mode Linux (UML);
• x86 architecture;
• Block layer subsystem;
• Cryptographic API;
• Compute Acceleration Framework;
• Intel NPU Driver;
• Speakup Console Speech Driver;
• ACPI drivers;
• Serial ATA and Parallel ATA drivers;
• Auxiliary display drivers;
• Drivers core;
• Micron PCIe SSD driver;
• Null block device driver;
• Ublk userspace block driver;
• Compressed RAM block device driver;
• Bluetooth drivers;
• Bus devices;
• AMD CDX bus driver;
• Hardware random number generator core;
• Character device driver;
• TPM device driver;
• Clock framework and drivers;
• Clocksource drivers;
• CPU frequency scaling framework;
• CPU idle management framework;
• Hardware crypto device drivers;
• CXL (Compute Express Link) drivers;
• DAX dirext access to differentiated memory framework;
• DIBS (Direct Internal Buffer Sharing) drivers;
• Buffer Sharing and Synchronization framework;
• DMA engine subsystem;
• EDAC drivers;
• FireWire subsystem;
• ARM SCMI message protocol;
• ARM SCPI message protocol;
• Google firmware drivers;
• Qualcomm firmware drivers;
• FPGA Framework;
• GPIO subsystem;
• GPU drivers;
• HID subsystem;
• HSI subsystem;
• Microsoft Hyper-V drivers;
• Hardware monitoring drivers;
• CoreSight HW tracing drivers;
• I2C subsystem;
• I3C subsystem;
• IIO subsystem;
• InfiniBand drivers;
• Input Device core drivers;
• Input Device (Miscellaneous) drivers;
• Input Device (Mouse) drivers;
• On-Chip Interconnect management framework;
• IOMMU subsystem;
• Industry Pack bus drivers;
• IRQ chip drivers;
• Mailbox framework;
• Media drivers;
• MemoryStick subsystem;
• Multifunction device drivers;
• Analog Devices digital potentiometer driver;
• Broadcom VK accelerator driver;
• Fastrpc Driver;
• Amazon Nitro Secure Module driver;
• SGI GRU driver;
• MMC subsystem;
• MTD block device drivers;
• Network drivers;
• Ethernet bonding driver;
• Mellanox network drivers;
• Microsoft Azure Network Adapter (MANA) driver;
• STMicroelectronics network drivers;
• Texas Instruments network drivers;
• MediaTek network drivers;
• Near Field Communication (NFC) drivers;
• NTB driver;
• NVDIMM (Non-Volatile Memory Device) drivers;
• NVME drivers;
• Device tree and open firmware driver;
• Operating Performance Points (OPP) driver;
• PA-RISC drivers;
• PCI subsystem;
• Performance monitor drivers;
• PHY drivers;
• Pin controllers subsystem;
• Chrome hardware platform drivers;
• Mellanox platform drivers;
• Microsoft Surface platform drivers;
• x86 platform drivers;
• MediaTek PM domains;
• Power sequencing drivers;
• Power supply drivers;
• Powercap sysfs driver;
• PTP clock framework;
• PWM drivers;
• RapidIO drivers;
• Voltage and Current Regulator drivers;
• Remote Processor subsystem;
• MPAM driver;
• RPMSG subsystem;
• Real Time Clock drivers;
• S/390 drivers;
• SCSI subsystem;
• ASPEED SoC drivers;
• Samsung SoC drivers;
• SPI subsystem;
• small TFT LCD display modules;
• Greybus lights staging drivers;
• Media staging drivers;
• Realtek RTL8723BS SDIO drivers;
• TCM subsystem;
• Trusted Execution Environment drivers;
• Thermal drivers;
• Thunderbolt and USB4 drivers;
• TTY drivers;
• UFS subsystem;
• Userspace I/O drivers;
• USB DSL drivers;
• Cypress C67X00 USB…

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:

• USB Gadget drivers;
• Memory management;
• Multiple devices driver;
• ARM64 architecture;
• EROFS file system;
• Networking core;
• eXpress Data Path;
• ARM32 architecture;
• M68K architecture;
• MIPS architecture;
• OpenRISC architecture;
• PA-RISC architecture;
• PowerPC architecture;
• RISC-V architecture;
• S390 architecture;
• User-Mode Linux (UML);
• x86 architecture;
• Block layer subsystem;
• Cryptographic API;
• Compute Acceleration Framework;
• Intel NPU Driver;
• Speakup Console Speech Driver;
• ACPI drivers;
• Serial ATA and Parallel ATA drivers;
• Auxiliary display drivers;
• Drivers core;
• Micron PCIe SSD driver;
• Null block device driver;
• Ublk userspace block driver;
• Compressed RAM block device driver;
• Bluetooth drivers;
• Bus devices;
• AMD CDX bus driver;
• Hardware random number generator core;
• Character device driver;
• TPM device driver;
• Clock framework and drivers;
• Clocksource drivers;
• CPU frequency scaling framework;
• CPU idle management framework;
• Hardware crypto device drivers;
• CXL (Compute Express Link) drivers;
• DAX dirext access to differentiated memory framework;
• DIBS (Direct Internal Buffer Sharing) drivers;
• Buffer Sharing and Synchronization framework;
• DMA engine subsystem;
• EDAC drivers;
• FireWire subsystem;
• ARM SCMI message protocol;
• ARM SCPI message protocol;
• Google firmware drivers;
• Qualcomm firmware drivers;
• FPGA Framework;
• GPIO subsystem;
• GPU drivers;
• HID subsystem;
• HSI subsystem;
• Microsoft Hyper-V drivers;
• Hardware monitoring drivers;
• CoreSight HW tracing drivers;
• I2C subsystem;
• I3C subsystem;
• IIO subsystem;
• InfiniBand drivers;
• Input Device core drivers;
• Input Device (Miscellaneous) drivers;
• Input Device (Mouse) drivers;
• On-Chip Interconnect management framework;
• IOMMU subsystem;
• Industry Pack bus drivers;
• IRQ chip drivers;
• Mailbox framework;
• Media drivers;
• MemoryStick subsystem;
• Multifunction device drivers;
• Analog Devices digital potentiometer driver;
• Broadcom VK accelerator driver;
• Fastrpc Driver;
• Amazon Nitro Secure Module driver;
• SGI GRU driver;
• MMC subsystem;
• MTD block device drivers;
• Network drivers;
• Ethernet bonding driver;
• Mellanox network drivers;
• Microsoft Azure Network Adapter (MANA) driver;
• STMicroelectronics network drivers;
• Texas Instruments network drivers;
• MediaTek network drivers;
• Near Field Communication (NFC) drivers;
• NTB driver;
• NVDIMM (Non-Volatile Memory Device) drivers;
• NVME drivers;
• Device tree and open firmware driver;
• Operating Performance Points (OPP) driver;
• PA-RISC drivers;
• PCI subsystem;
• Performance monitor drivers;
• PHY drivers;
• Pin controllers subsystem;
• Chrome hardware platform drivers;
• Mellanox platform drivers;
• Microsoft Surface platform drivers;
• x86 platform drivers;
• MediaTek PM domains;
• Power sequencing drivers;
• Power supply drivers;
• Powercap sysfs driver;
• PTP clock framework;
• PWM drivers;
• RapidIO drivers;
• Voltage and Current Regulator drivers;
• Remote Processor subsystem;
• MPAM driver;
• RPMSG subsystem;
• Real Time Clock drivers;
• S/390 drivers;
• SCSI subsystem;
• ASPEED SoC drivers;
• Samsung SoC drivers;
• SPI subsystem;
• small TFT LCD display modules;
• Greybus lights staging drivers;
• Media staging drivers;
• Realtek RTL8723BS SDIO drivers;
• TCM subsystem;
• Trusted Execution Environment drivers;
• Thermal drivers;
• Thunderbolt and USB4 drivers;
• TTY drivers;
• UFS subsystem;
• Userspace I/O drivers;
• USB DSL drivers;
• Cypress C67X00 USB…