+ mm-damon-sysfs-schemes-skip-stats-update-if-the-scheme-directory-is-removed.patch added to mm-hotfixes-unstable branch

[Andrew Morton <akpm@linux-foundation.org>]

The patch titled
     Subject: mm/damon/sysfs-schemes: skip stats update if the scheme directory is removed
has been added to the -mm mm-hotfixes-unstable branch.  Its filename is
     mm-damon-sysfs-schemes-skip-stats-update-if-the-scheme-directory-is-removed.patch

This patch will shortly appear at
     https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-damon-sysfs-schemes-skip-stats-update-if-the-scheme-directory-is-removed.patch

This patch will later appear in the mm-hotfixes-unstable branch at
    git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

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------------------------------------------------------
From: SeongJae Park <sj@kernel.org>
Subject: mm/damon/sysfs-schemes: skip stats update if the scheme directory is removed
Date: Mon, 14 Nov 2022 17:55:52 +0000

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: 0ac32b8affb5 ("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>
---

 mm/damon/sysfs.c |    4 ++++
 1 file changed, 4 insertions(+)

--- a/mm/damon/sysfs.c~mm-damon-sysfs-schemes-skip-stats-update-if-the-scheme-directory-is-removed
+++ a/mm/damon/sysfs.c
@@ -2339,6 +2339,10 @@ static int damon_sysfs_upd_schemes_stats
 	damon_for_each_scheme(scheme, ctx) {
 		struct damon_sysfs_stats *sysfs_stats;
 
+		/* user could 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;
_

Patches currently in -mm which might be from sj@kernel.org are

mm-damon-sysfs-schemes-skip-stats-update-if-the-scheme-directory-is-removed.patch
docs-admin-guide-mm-damon-usage-describe-the-rules-of-sysfs-region-directories.patch
docs-admin-guide-mm-damon-usage-fix-wrong-usage-example-of-init_regions-file.patch
mm-damon-core-add-a-callback-for-scheme-target-regions-check.patch
mm-damon-sysfs-schemes-implement-schemes-tried_regions-directory.patch
mm-damon-sysfs-schemes-implement-scheme-region-directory.patch
mm-damon-sysfs-implement-damos-tried-regions-update-command.patch
mm-damon-sysfs-implement-damos-tried-regions-update-command-fix.patch
mm-damon-sysfs-schemes-implement-damos-tried-regions-clear-command.patch
mm-damon-sysfs-schemes-implement-damos-tried-regions-clear-command-fix.patch
tools-selftets-damon-sysfs-test-tried_regions-directory-existence.patch
docs-admin-guide-mm-damon-usage-document-schemes-s-tried_regions-sysfs-directory.patch
docs-abi-damon-document-schemes-s-tried_regions-sysfs-directory.patch
selftests-damon-test-non-context-inputs-to-rm_contexts-file.patch