Re: [PATCH v3 08/10] ACPI: APEI: GHES: Validate memory error section length before payload access

[Alison Schofield <alison.schofield@intel.com>]

On Fri, Jul 17, 2026 at 09:16:45AM -0700, Dave Jiang wrote:
> sashiko-bot flagged that the memory error length check was placed too
> late, leaving the other payload consumers unprotected.
> 
> ghes_do_proc() hands the CPER_SEC_PLATFORM_MEM payload to the report
> chain, arch_apei_report_mem_error() and ghes_handle_memory_failure()
> without checking gdata->error_data_length. These read validation_bits
> and physical_addr (offsets 0 and 16), so a shorter section reads past the
> record.
> 
> Validate error_data_length once in ghes_do_proc(), before any consumer
> runs, so every consumer is covered. Bound against struct
> cper_sec_mem_err_old (the UEFI 2.1/2.2 layout) rather than the full
> struct: the section length is authoritative, older firmware legitimately
> emits the shorter record, and the trailing fields, though packed
> unconditionally by cper_mem_err_pack(), are only acted on under
> validation bits that a short record leaves clear. This matches the lower
> bound already used in drivers/firmware/efi/cper.c.
> 
> A malformed sub-record no longer reaches ghes_handle_memory_failure().
> 
> Reported-by: sashiko-bot@kernel.org
> Closes: https://sashiko.dev/#/patchset/20260714231835.303081-1-dave.jiang@intel.com?part=7
> Fixes: ca104edc1784 ("ACPI, APEI, GHES: Cleanup ghes memory error handling")
> Assisted-by: Claude:claude-opus-4-8
> Signed-off-by: Dave Jiang <dave.jiang@intel.com>

Reviewed-by: Alison Schofield <alison.schofield@intel.com>