CVE-2024-42126 — powerpc: Avoid nmi_enter/nmi_exit in real mode interrupt.

Affected: Linux

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

powerpc: Avoid nmi_enter/nmi_exit in real mode interrupt.

nmi_enter()/nmi_exit() touches per cpu variables which can lead to kernel crash when invoked during real mode interrupt handling (e.g. early HMI/MCE interrupt handler) if percpu allocation comes from vmalloc area.

Early HMI/MCE handlers are called through DEFINE_INTERRUPT_HANDLER_NMI() wrapper which invokes nmi_enter/nmi_exit calls. We don't see any issue when percpu allocation is from the embedded first chunk. However with CONFIG_NEED_PER_CPU_PAGE_FIRST_CHUNK enabled there are chances where percpu allocation can come from the vmalloc area.

With kernel command line "percpu_alloc=page" we can force percpu allocation to come from vmalloc area and can see kernel crash in machine_check_early:

[ 1.215714] NIP [c000000000e49eb4] rcu_nmi_enter+0x24/0x110 [ 1.215717] LR [c0000000000461a0] machine_check_early+0xf0/0x2c0 [ 1.215719] --- interrupt: 200 [ 1.215720] [c000000fffd73180] [0000000000000000] 0x0 (unreliable) [ 1.215722] [c000000fffd731b0] [0000000000000000] 0x0 [ 1.215724] [c000000fffd73210] [c000000000008364] machine_check_early_common+0x134/0x1f8

Fix this by avoiding use of nmi_enter()/nmi_exit() in real mode if percpu first chunk is not embedded.

USN-7089-1 — linux, linux-gcp-6.8, linux-hwe-6.8 vulnerabilities

Affected: Ubuntu:22.04:LTS: linux-gcp-6.8, Ubuntu:22.04:LTS: linux-hwe-6.8, Ubuntu:24.04:LTS: linux

Chenyuan Yang discovered that the USB Gadget subsystem in the Linux kernel did not properly check for the device to be enabled before writing. A local attacker could possibly use this to cause a denial of service. (CVE-2024-25741)

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; - MIPS architecture; - PA-RISC architecture; - PowerPC architecture; - RISC-V architecture; - S390 architecture; - x86 architecture; - Cryptographic API; - Serial ATA and Parallel ATA drivers; - Null block device driver; - Bluetooth drivers; - Cdrom driver; - Clock framework and drivers; - Hardware crypto device drivers; - CXL (Compute Express Link) drivers; - Cirrus firmware drivers; - GPIO subsystem; - GPU drivers; - I2C subsystem; - IIO subsystem; - InfiniBand drivers; - ISDN/mISDN subsystem; - LED subsystem; - Multiple devices driver; - Media drivers; - Fastrpc Driver; - Network drivers; - Microsoft Azure Network Adapter (MANA) driver; - Near Field Communication (NFC) drivers; - NVME drivers; - NVMEM (Non Volatile Memory) drivers; - PCI subsystem; - Pin controllers subsystem; - x86 platform drivers; - S/390 drivers; - SCSI drivers; - Thermal drivers; - TTY drivers; - UFS subsystem; - USB DSL drivers; - USB core drivers; - DesignWare USB3 driver; - USB Gadget dr…

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CVE-2024-42126 — powerpc: Avoid nmi_enter/nmi_exit in real mode interrupt.

USN-7089-1 — linux, linux-gcp-6.8, linux-hwe-6.8 vulnerabilities