Commit 8468b486 authored by SeongJae Park's avatar SeongJae Park Committed by Andrew Morton
Browse files

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/20221114175552.1951-1-sj@kernel.org


Fixes: 0ac32b8a ("mm/damon/sysfs: support DAMOS stats")
Signed-off-by: default avatarSeongJae Park <sj@kernel.org>
Cc: <stable@vger.kernel.org>	[v5.18]
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
parent 4a955bed

mm/damon/sysfs.c

+4 −0
Original line number Diff line number Diff line
@@ -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;