CVE-2024-38613 — m68k: Fix spinlock race in kernel thread creation

Affected: Linux

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

m68k: Fix spinlock race in kernel thread creation

Context switching does take care to retain the correct lock owner across the switch from 'prev' to 'next' tasks. This does rely on interrupts remaining disabled for the entire duration of the switch.

This condition is guaranteed for normal process creation and context switching between already running processes, because both 'prev' and 'next' already have interrupts disabled in their saved copies of the status register.

The situation is different for newly created kernel threads. The status register is set to PS_S in copy_thread(), which does leave the IPL at 0. Upon restoring the 'next' thread's status register in switch_to() aka resume(), interrupts then become enabled prematurely. resume() then returns via ret_from_kernel_thread() and schedule_tail() where run queue lock is released (see finish_task_switch() and finish_lock_switch()).

A timer interrupt calling scheduler_tick() before the lock is released in finish_task_switch() will find the lock already taken, with the current task as lock owner. This causes a spinlock recursion warning as reported by Guenter Roeck.

As far as I can ascertain, this race has been opened in commit 533e6903bea0 ("m68k: split ret_from_fork(), simplify kernel_thread()") but I haven't done a detailed study of kernel history so it may well predate that commit.

Interrupts cannot be disabled in the saved status register…

USN-6949-1 — linux, linux-aws, linux-gcp, linux-gke, linux-ibm, linux-nvidia, linux-nvidia-6.8 vulnerabilities

Affected: Ubuntu:22.04:LTS: linux-nvidia-6.8, Ubuntu:24.04:LTS: linux, Ubuntu:24.04:LTS: linux-aws, Ubuntu:24.04:LTS: linux-gcp, Ubuntu:24.04:LTS: linux-gke, Ubuntu:24.04:LTS: linux-ibm, Ubuntu:24.04:LTS: linux-nvidia

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: - ARM32 architecture; - ARM64 architecture; - M68K architecture; - OpenRISC architecture; - PowerPC architecture; - RISC-V architecture; - x86 architecture; - Block layer subsystem; - Accessibility subsystem; - Bluetooth drivers; - Clock framework and drivers; - CPU frequency scaling framework; - Hardware crypto device drivers; - DMA engine subsystem; - DPLL subsystem; - FireWire subsystem; - EFI core; - Qualcomm firmware drivers; - GPIO subsystem; - GPU drivers; - Microsoft Hyper-V drivers; - InfiniBand drivers; - IOMMU subsystem; - IRQ chip drivers; - Macintosh device drivers; - Multiple devices driver; - Media drivers; - EEPROM drivers; - MMC subsystem; - Network drivers; - STMicroelectronics network drivers; - Device tree and open firmware driver; - HiSilicon SoC PMU drivers; - PHY drivers; - Pin controllers subsystem; - Remote Processor subsystem; - S/390 drivers; - SCSI drivers; - SPI subsystem; - Media staging drivers; - Thermal drivers; - Userspace I/O drivers; - USB subsystem; - DesignWare USB3 driver; - ACRN Hypervisor Service Module driver; - Virtio drivers; - 9P distributed file system; - BTRFS file system; - eCrypt file system; - EROFS file system; - File systems infrastructure; - GF…

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CVE-2024-38613 — m68k: Fix spinlock race in kernel thread creation

USN-6949-1 — linux, linux-aws, linux-gcp, linux-gke, linux-ibm, linux-nvidia, linux-nvidia-6.8 vulnerabilities