CVE-2026-99240

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

mm/damon/core: error damos commit quota goal() for zero target value

Patch series "mm/damon: move zero damos quota target value handling to the core layer".

Having zero DAMOS quota target value can cause division by zero. DAMON API callers are checking the target value parameters to avoid that. It is easy to make mistakes in some of the multiple API callers. Move that to the core layer.

Patch 1 adds the corner case handling into the core layer DAMON parameters validation logic. Patches 2 and 3 remove no more needed DAMON API callers side handling of the corner case in DAMON LRU SORT and DMON SAMPLIE MTIER, respectively.

This patch (of 3):

If a DAMOS scheme has a damos quota goal of zero target value, damos quota goal() could trigger division-by-zero error. Hence each DAMON API callers should do the zero target value validation. It is easy to make mistakes. Actually such bugs in DAMON LRU SORT and DAMON SAMPLE MTIER were found and fixed [1].

It is better to handle the corner case only once in the core layer, instead of multiple places in all DAMON API callers. One straightforward option is using an alternative denominator for the corner case in the damos quota goal(). However, the zero target value is meaningless. In this case, the quota goal is always evaluated as achieved or over-achieved. The quota will only keep being reduced.

Simply avoid using zero target value by adding a check in the core layer DAMOS quota goal parameters validation/commit path, damos commit quota goal(). Update it to return an error in the case. Also update its caller to propagate the error.