CVE-2026-89587

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

ACPI: pfr update: fix stack buffer overflow in query capability()

query capability() copies four ACPI buffer objects returned by the firmware DSM into fixed-size u8[16] fields in struct pfru update cap info using memcpy with the firmware-supplied length:

memcpy(&cap hdr->code type, elements[CAP CODE TYPE IDX].buffer.pointer, elements[CAP CODE TYPE IDX].buffer.length);

The same pattern repeats for drv type, platform id, and oem id. If the firmware returns buffer.length > 16 for any of these fields, memcpy writes past the destination array.

struct pfru update cap info is stack-allocated in pfru ioctl().

Confirmed with KASAN on 7.2-rc6: three stack-out-of-bounds reports are generated when a DSM returns 64-byte buffers, with writes reaching 44 bytes past the end of cap hdr's [64, 156) frame window into adjacent stack redzones.

Introduce a helper pointer to out obj->package.elements and use it to validate each buffer length against its destination field size before copying, returning -EINVAL if the firmware supplies an oversized buffer.