CVE-2025-39763

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

ACPI: APEI: send SIGBUS to current task if synchronous memory error not recovered

If a synchronous error is detected as a result of user-space process

triggering a 2-bit uncorrected error, the CPU will take a synchronous

error exception such as Synchronous External Abort (SEA) on Arm64. The

kernel will queue a memory_failure() work which poisons the related

page, unmaps the page, and then sends a SIGBUS to the process, so that

a system wide panic can be avoided.

However, no memory_failure() work will be queued when abnormal

synchronous errors occur. These errors can include situations like

invalid PA, unexpected severity, no memory failure config support,

invalid GUID section, etc. In such a case, the user-space process will

trigger SEA again. This loop can potentially exceed the platform

firmware threshold or even trigger a kernel hard lockup, leading to a

system reboot.

Fix it by performing a force kill if no memory_failure() work is queued

for synchronous errors.

[ rjw: Changelog edits ]