Medium [CVE-2026-80627] Fix out-of-bounds write in maar_res_walk

In the Linux kernel, the following vulnerability has been resolved: MIPS: mm: Fix out-of-bounds write in maar_res_walk() maar_res_walk() uses wi->num_cfg as the index into the fixed-size wi->cfg array, but checks whether the array is full only after it has filled the selected entry.

If walk_system_ram_range() reports more than 16 memory ranges, the overflow call writes one struct maar_config past the end of the array before WARN_ON() prevents num_cfg from advancing.

Move the full-array check before taking the array slot and return non-zero when the scratch array is full, so walk_system_ram_range() terminates the walk instead of invoking the callback for further ranges. A flaw was found in the Linux kernel, specifically within the MIPS architecture's memory management component.

The `maar_res_walk()` function performs an out-of-bounds write when processing memory ranges. This occurs because the function fails to check if its internal array is full before writing new data, potentially leading to memory corruption if more than 16 memory ranges are reported.

A local attacker could exploit this vulnerability to cause system instability or a denial of service (DoS). Red Hat severity: Moderate — CVSS 5.5 (CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H).

Weakness: CWE-787.