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

commit 8468b48661 upstream.

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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
SeongJae Park 2022-11-14 17:55:52 +00:00 committed by Greg Kroah-Hartman
parent 3398bf9b0d
commit dfb8a23d93
1 changed files with 4 additions and 0 deletions
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4
mm/damon/sysfs.c
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@ -2342,6 +2342,10 @@ 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;