mm/damon/sysfs-schemes: put damos dests dir after removing its files

damon_sysfs_scheme_rm_dirs() puts dests directory kobject before removing
its internal files.  Sincee putting the kobject frees its container
struct, and the internal files removal accesses the container,
use-after-free happens.  Fix it by putting the reference _after_ removing
the files.

Link: https://lkml.kernel.org/r/20250816165559.2601-1-sj@kernel.org
Fixes: 2cd0bf85a203 ("mm/damon/sysfs-schemes: implement DAMOS action destinations directory")
Signed-off-by: SeongJae Park <sj@kernel.org>
Reported-by: Alexandre Ghiti <alex@ghiti.fr>
Closes: https://lore.kernel.org/2d39a734-320d-4341-8f8a-4019eec2dbf2@ghiti.fr
Tested-by: Alexandre Ghiti <alexghiti@rivosinc.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/mm/damon/sysfs-schemes.c b/mm/damon/sysfs-schemes.c
index 74056bcd6a2c58a75f8df8f6c4d8baa631c996a9..6536f16006c90f0d130abf11339cfcf05317ffe8 100644 (file)
--- a/mm/damon/sysfs-schemes.c
+++ b/mm/damon/sysfs-schemes.c
@@ -2158,8 +2158,8 @@ static void damon_sysfs_scheme_rm_dirs(struct damon_sysfs_scheme *scheme)
 {
        damon_sysfs_access_pattern_rm_dirs(scheme->access_pattern);
        kobject_put(&scheme->access_pattern->kobj);
-       kobject_put(&scheme->dests->kobj);
        damos_sysfs_dests_rm_dirs(scheme->dests);
+       kobject_put(&scheme->dests->kobj);
        damon_sysfs_quotas_rm_dirs(scheme->quotas);
        kobject_put(&scheme->quotas->kobj);
        kobject_put(&scheme->watermarks->kobj);