CVE-2025-38670 — arm64/entry: Mask DAIF in cpu_switch_to(), call_on_irq_stack()

Affected: Linux, Siemens SIMATIC CN 4100

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

arm64/entry: Mask DAIF in cpu_switch_to(), call_on_irq_stack()

`cpu_switch_to()` and `call_on_irq_stack()` manipulate SP to change to different stacks along with the Shadow Call Stack if it is enabled. Those two stack changes cannot be done atomically and both functions can be interrupted by SErrors or Debug Exceptions which, though unlikely, is very much broken : if interrupted, we can end up with mismatched stacks and Shadow Call Stack leading to clobbered stacks.

In `cpu_switch_to()`, it can happen when SP_EL0 points to the new task, but x18 stills points to the old task's SCS. When the interrupt handler tries to save the task's SCS pointer, it will save the old task SCS pointer (x18) into the new task struct (pointed to by SP_EL0), clobbering it.

In `call_on_irq_stack()`, it can happen when switching from the task stack to the IRQ stack and when switching back. In both cases, we can be interrupted when the SCS pointer points to the IRQ SCS, but SP points to the task stack. The nested interrupt handler pushes its return addresses on the IRQ SCS. It then detects that SP points to the task stack, calls `call_on_irq_stack()` and clobbers the task SCS pointer with the IRQ SCS pointer, which it will also use !

This leads to tasks returning to addresses on the wrong SCS, or even on the IRQ SCS, triggering kernel panics via CONFIG_VMAP_STACK or FPAC if enabled.

This is possible on a default config, but unl…

USN-7879-1 — linux, linux-aws, linux-gcp, linux-hwe-6.14, linux-oracle, linux-realtime vulnerabilities

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

It was discovered that improper initialization of CPU cache memory could allow a local attacker with hypervisor access to overwrite SEV-SNP guest memory resulting in loss of data integrity. (CVE-2024-36331)

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; - S390 architecture; - x86 architecture; - Network block device driver; - Character device driver; - Clock framework and drivers; - Data acquisition framework and drivers; - Hardware crypto device drivers; - Device frequency scaling framework; - DMA engine subsystem; - EDAC drivers; - GPU drivers; - HID subsystem; - Hardware monitoring drivers; - I2C subsystem; - IIO subsystem; - IIO ADC drivers; - InfiniBand drivers; - Input Device core drivers; - Multiple devices driver; - Media drivers; - Network drivers; - Mellanox network drivers; - PCI subsystem; - PHY drivers; - Pin controllers subsystem; - x86 platform drivers; - Power supply drivers; - Powercap sysfs driver; - Voltage and Current Regulator drivers; - S/390 drivers; - ASPEED SoC drivers; - SPI subsystem; - small TFT LCD display modules; - Media staging drivers; - USB Gadget drivers; - vDPA drivers; - VFIO drivers; - Framebuffer layer; - Xen hypervisor drivers; - BTRFS file system; - Ceph distributed file sy…

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CVE-2025-38670 — arm64/entry: Mask DAIF in cpu_switch_to(), call_on_irq_stack()

USN-7879-1 — linux, linux-aws, linux-gcp, linux-hwe-6.14, linux-oracle, linux-realtime vulnerabilities