ACPI: pfr_update: fix stack buffer overflow in query_capability()

Overview

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

• Linux >= 0db89fa243e5edc5de38c88b369e4c3755c5fb74 < d3af83e327565a9444cebc0db714cb837e493046
• Linux >= 0db89fa243e5edc5de38c88b369e4c3755c5fb74 < c5a31b4e7e37c92550be9a2edf51ca853a4d251a
• Linux >= 0db89fa243e5edc5de38c88b369e4c3755c5fb74 < a2151624b55029dad0ca7efd17fb83a0461c8843
• Linux >= 0db89fa243e5edc5de38c88b369e4c3755c5fb74 < 6d4ed2fd022bc862b156e53aae163b61259e1caa
• Linux >= 0db89fa243e5edc5de38c88b369e4c3755c5fb74 < 15d2b7f38f95d28652170344f39ee492c55e567c
• Linux >= 0db89fa243e5edc5de38c88b369e4c3755c5fb74 < ced45be0073a8a31b30b4a7f68cd3a15734515de
• Linux 5.17

Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.

Vendor advisories

• Red Hat VEX · Moderate · affected: Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 9, Red Hat OpenShift Container Platform 4 · no fix planned: Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 9, Red Hat OpenShift Container Platform 4 · updated 2026-09-21 · vex