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: 0ac32b8aff ("mm/damon/sysfs: support DAMOS stats")
Signed-off-by: SeongJae Park <sj@kernel.org>
Cc: <stable@vger.kernel.org>	[v5.18]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
SeongJae Park 2022-11-14 17:55:52 +00:00 committed by Andrew Morton
parent 4a955bed88
commit 8468b48661

View file

@ -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;