CVE-2026-89588: Undefined Security Weakness

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

ACPI: APEI: GHES: fix ARM section length accounting after header

In ghes_handle_arm_hw_error(), after skipping the cper_sec_proc_arm header with (err + 1), the remaining length was reduced by sizeof(err) (pointer size) instead of sizeof(*err) (structure size).

That overestimates the bytes left for cper_arm_err_info records and can let the parser read past the CPER section when err_info_num is large enough relative to error_data_length.

Use sizeof(*err) so the length accounting matches the pointer advance and the earlier sizeof(*err) size check.