+ mm-damon-sysfs-schemes-fix-dir-put-orders-in-access_pattern_add_dirs.patch added to mm-hotfixes-unstable branch

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

The patch titled
     Subject: mm/damon/sysfs-schemes: fix dir put orders in access_pattern_add_dirs()
has been added to the -mm mm-hotfixes-unstable branch.  Its filename is
     mm-damon-sysfs-schemes-fix-dir-put-orders-in-access_pattern_add_dirs.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-fix-dir-put-orders-in-access_pattern_add_dirs.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: fix dir put orders in access_pattern_add_dirs()
Date: Wed, 17 Jun 2026 17:56:47 -0700

Patch series "mm/damon/sysfs-schemes: fix wrong directories put orders in
error paths".

Error paths of damon_sysfs_access_pattern_add_dirs() and
damon_sysfs_scheme_add_dirs() functions put references to directories in
wrong orders.  As a result, uninitialized memory dereference and/or
memory leak can happen.  Fix those.


This patch (of 2):

In access_pattern_add_dirs(), error handling path puts references starting
from setup failed directories.  If the failure happpened from the initial
allication in the setup functions, uninitialized memory dereference
happen.  The allocation failures will not commonly happen, but the
consequence is quite bad.  Fix the wrong reference put orders.

The issue was discovered [1] by Sashiko.

Link: https://lore.kernel.org/20260618005650.83868-2-sj@kernel.org
Link: https://lore.kernel.org/20260617060005.86852-1-sj@kernel.org [1]
Fixes: 7e84b1f8212a ("mm/damon/sysfs: support DAMON-based Operation Schemes")
Signed-off-by: SeongJae Park <sj@kernel.org>
Cc: <stable@vger.kernel.org> # 5.18.x
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 mm/damon/sysfs-schemes.c |    9 +++------
 1 file changed, 3 insertions(+), 6 deletions(-)

--- a/mm/damon/sysfs-schemes.c~mm-damon-sysfs-schemes-fix-dir-put-orders-in-access_pattern_add_dirs
+++ a/mm/damon/sysfs-schemes.c
@@ -1767,22 +1767,19 @@ static int damon_sysfs_access_pattern_ad
 	err = damon_sysfs_access_pattern_add_range_dir(access_pattern,
 			&access_pattern->sz, "sz");
 	if (err)
-		goto put_sz_out;
+		return err;
 
 	err = damon_sysfs_access_pattern_add_range_dir(access_pattern,
 			&access_pattern->nr_accesses, "nr_accesses");
 	if (err)
-		goto put_nr_accesses_sz_out;
+		goto put_sz_out;
 
 	err = damon_sysfs_access_pattern_add_range_dir(access_pattern,
 			&access_pattern->age, "age");
 	if (err)
-		goto put_age_nr_accesses_sz_out;
+		goto put_nr_accesses_sz_out;
 	return 0;
 
-put_age_nr_accesses_sz_out:
-	kobject_put(&access_pattern->age->kobj);
-	access_pattern->age = NULL;
 put_nr_accesses_sz_out:
 	kobject_put(&access_pattern->nr_accesses->kobj);
 	access_pattern->nr_accesses = NULL;
_

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

mm-damon-sysfs-schemes-fix-dir-put-orders-in-access_pattern_add_dirs.patch
mm-damon-sysfs-schemes-put-stats-for-scheme_add_dirs-internal-error.patch
mm-damon-core-always-put-unsuccessfully-committed-target-pids.patch