[merged mm-stable] mm-damon-core-validate-params-for-probe-hits-weighted-sum-overflow.patch removed from -mm tree

The quilt patch titled
     Subject: mm/damon/core: validate params for probe hits weighted sum overflow
has been removed from the -mm tree.  Its filename was
     mm-damon-core-validate-params-for-probe-hits-weighted-sum-overflow.patch

This patch was dropped because it was merged into the mm-stable branch
of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

------------------------------------------------------
From: SJ Park <[email protected]>
Subject: mm/damon/core: validate params for probe hits weighted sum overflow
Date: Fri, 10 Jul 2026 06:46:39 -0700

damon_probe_hits_wsum() could overflow in weird setups.  Users could set
the weight unreasonably high.  They could also set the aggregation
interval unreasonably high compared to the sampling interval.  Such user
setup is unlikely.  Even if such setup is used, damon_has_probe_weights()
always returns false, so the overflow cannot happen.  The function may be
completed in future, though.  Even if the overflow happens, the
consequence is degraded monitoring results for the unreasonable setup.  It
is just a trivial user experience issue.

It is still better to be prevented unless the cost is expensive.  Avoid
the overflow by adding the parameter validation in the core layer
parameters validation function.

Link: https://lore.kernel.org/[email protected]
Signed-off-by: SJ Park <[email protected]>
Cc: David Hildenbrand <[email protected]>
Cc: Jonathan Corbet <[email protected]>
Cc: Liam R. Howlett <[email protected]>
Cc: Lorenzo Stoakes <[email protected]>
Cc: Michal Hocko <[email protected]>
Cc: Mike Rapoport <[email protected]>
Cc: Suren Baghdasaryan <[email protected]>
Cc: Vlastimil Babka <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
---

 mm/damon/core.c |   15 +++++++++++++++
 1 file changed, 15 insertions(+)

--- a/mm/damon/core.c~mm-damon-core-validate-params-for-probe-hits-weighted-sum-overflow
+++ a/mm/damon/core.c
@@ -1335,6 +1335,9 @@ static void damos_set_filters_default_re
 static bool damon_valid_probe_params(struct damon_ctx *ctx)
 {
 	unsigned long sample_interval;
+	unsigned char max_probe_hits;
+	struct damon_probe *probe;
+	unsigned int wsum, wsum_to_add;
 
 	if (!damon_has_probe_weights(ctx))
 		return true;
@@ -1342,6 +1345,18 @@ static bool damon_valid_probe_params(str
 	sample_interval = ctx->attrs.sample_interval ? : 1;
 	if (ctx->attrs.aggr_interval / sample_interval > U8_MAX)
 		return false;
+
+	/* invalid if probe hits weighted sum can overflow */
+	max_probe_hits = damon_nr_samples_per_aggr(&ctx->attrs);
+	wsum = 0;
+	damon_for_each_probe(probe, ctx) {
+		if (probe->weight > UINT_MAX / max_probe_hits)
+			return false;
+		wsum_to_add = probe->weight * max_probe_hits;
+		if (UINT_MAX - wsum < wsum_to_add)
+			return false;
+		wsum += wsum_to_add;
+	}
 	return true;
 }
 
_

Patches currently in -mm which might be from [email protected] are

mm-damon-adjust-isolated-pages-stat-for-damos_migrate_hotcold.patch
samples-damon-mtier-error-out-for-zero-quota-goal-target-values.patch
mm-damon-lru_sort-error-out-for-10000-active_mem_bp.patch
mm-damon-reclaim-skip-damon_call-if-ctx-has-not-started.patch
mm-damon-lru_sort-skip-damon_call-if-ctx-has-not-started.patch
mm-damon-core-skip-aging-from-repeated-aggressive-merging.patch
mm-damon-core-hide-private-damon_region-fields.patch
mm-damon-core-hide-private-damon_target-fields.patch
mm-damon-core-hide-private-damos_quota_goal-fields.patch
mm-damon-core-hide-private-damos_quota-fields.patch
mm-damon-core-hide-private-damos_filter-fields.patch
mm-damon-core-hide-private-damos-fields.patch
mm-damon-core-hide-private-damon_filter-fields.patch
mm-damon-core-hide-private-damon_probe-fields.patch
mm-damon-sysfs-do-not-directly-access-damon_ctx-ops.patch
mm-damon-core-hide-core-private-damon_ctx-fields.patch
mm-damon-core-avoid-infinite-kdamond_merge_regions-internal-loop.patch
mm-damon-tests-core-kunit-catch-test-failure-in-test_merge_regions_of.patch
mm-damon-vaddr-drop-last-same-folio-access-check-optimization.patch
mm-damon-paddr-drop-last-same-folio-access-check-reuse-optimization.patch
mm-damon-sysfs-read-addr_unit-only-once-in-damon_sysfs_apply_inputs.patch
mm-damon-sysfs-read-ops_id-only-once-in-damon_sysfs_apply_inputs.patch
mm-damon-core-initialize-damos-last_applied.patch
mm-damon-core-kunit-check-region-count-before-testing-in-split_at.patch
mm-damon-vaddr-kunit-check-region-count-in-three_regions-test.patch
mm-damon-core-kunit-handle-region-split-failure-in-filter_out.patch
mm-damon-core-kunit-skip-wrong-dest-walk-in-commit_dests_for.patch
mm-damon-core-kunit-skip-wrong-quota-goal-walk-in-commit_quota_goals.patch
mm-damon-core-kunit-skip-wrong-region-walk-in-commit_target_regions.patch
mm-damon-ops-common-use-nr_accesses-moving-sum-for-quota-score.patch
mm-damon-core-handle-region-split-failure-in-apply_min_nr_regions.patch