CVE-2026-89587ACPI: pfr_update: fix stack buffer overflow in query_capability()

Official description

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.

Affected packages & fixed versions

Affected products (as reported)

References

• https://git.kernel.org/stable/c/d3af83e327565a9444cebc0db714cb837e493046
• https://git.kernel.org/stable/c/c5a31b4e7e37c92550be9a2edf51ca853a4d251a
• https://git.kernel.org/stable/c/a2151624b55029dad0ca7efd17fb83a0461c8843
• https://git.kernel.org/stable/c/6d4ed2fd022bc862b156e53aae163b61259e1caa
• https://git.kernel.org/stable/c/15d2b7f38f95d28652170344f39ee492c55e567c
• https://git.kernel.org/stable/c/ced45be0073a8a31b30b4a7f68cd3a15734515de