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.

Fixes: 0db89fa243e5 ("ACPI: Introduce Platform Firmware Runtime Update device driver")
Cc: All applicable <stable@vger.kernel.org>
Signed-off-by: Anirudh Prasad <icarus@a0rg.com>
Link: https://patch.msgid.link/1a001e1fee9.637da6dc3533246.238498880682901704@a0rg.com
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

0 files changed, 0 insertions, 0 deletions