mm/damon/sysfs-schemes: skip stats update if the scheme directory is …

…removed A DAMON sysfs interface user can start DAMON with a scheme, remove the sysfs directory for the scheme, and then ask update of the scheme's stats. Because the schemes stats update logic isn't aware of the situation, it results in an invalid memory access. Fix the bug by checking if the scheme sysfs directory exists. Link: https://lkml.kernel.org/r/[email protected] Fixes: 0ac32b8 ("mm/damon/sysfs: support DAMOS stats") Signed-off-by: SeongJae Park <[email protected]> Cc: <[email protected]> [v5.18] Signed-off-by: Andrew Morton <[email protected]>
intel-lab-lkp · Nov 23, 2022 · 8468b48 · 8468b48
1 parent 4a955be
commit 8468b48
Showing 1 changed file with 4 additions and 0 deletions.
diff --git a/mm/damon/sysfs.c b/mm/damon/sysfs.c
@@ -2339,6 +2339,10 @@ static int damon_sysfs_upd_schemes_stats(struct damon_sysfs_kdamond *kdamond)
 	damon_for_each_scheme(scheme, ctx) {
 		struct damon_sysfs_stats *sysfs_stats;
 
+		/* user could have removed the scheme sysfs dir */
+		if (schemes_idx >= sysfs_schemes->nr)
+			break;
+
 		sysfs_stats = sysfs_schemes->schemes_arr[schemes_idx++]->stats;
 		sysfs_stats->nr_tried = scheme->stat.nr_tried;
 		sysfs_stats->sz_tried = scheme->stat.sz_tried;