[PATCH 6.6 283/530] mm/damon/sysfs-schemes: handle tried region directory allocation failure

[Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>]

6.6-stable review patch.  If anyone has any objections, please let me know.

------------------

From: SeongJae Park <sj@xxxxxxxxxx>

commit ae636ae2bbfd9279f5681dbf320d1da817e52b68 upstream.

DAMON sysfs interface's before_damos_apply callback
(damon_sysfs_before_damos_apply()), which creates the DAMOS tried regions
for each DAMOS action applied region, is not handling the allocation
failure for the sysfs directory data.  As a result, NULL pointer
derefeence is possible.  Fix it by handling the case.

Link: https://lkml.kernel.org/r/20231106233408.51159-4-sj@xxxxxxxxxx
Fixes: f1d13cacabe1 ("mm/damon/sysfs: implement DAMOS tried regions update command")
Signed-off-by: SeongJae Park <sj@xxxxxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx>	[6.2+]
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
 mm/damon/sysfs-schemes.c |    2 ++
 1 file changed, 2 insertions(+)

--- a/mm/damon/sysfs-schemes.c
+++ b/mm/damon/sysfs-schemes.c
@@ -1752,6 +1752,8 @@ static int damon_sysfs_before_damos_appl
 		return 0;
 
 	region = damon_sysfs_scheme_region_alloc(r);
+	if (!region)
+		return 0;
 	list_add_tail(&region->list, &sysfs_regions->regions_list);
 	sysfs_regions->nr_regions++;
 	if (kobject_init_and_add(&region->kobj,