From: SeongJae Park Date: Thu, 19 Jun 2025 18:36:07 +0000 (-0700) Subject: mm/damon/sysfs-schemes: free old damon_sysfs_scheme_filter->memcg_path on write X-Git-Url: https://git.kernel.dk/?a=commitdiff_plain;h=4f489fe6afb395dbc79840efa3c05440b760d883;p=linux-block.git mm/damon/sysfs-schemes: free old damon_sysfs_scheme_filter->memcg_path on write memcg_path_store() assigns a newly allocated memory buffer to filter->memcg_path, without deallocating the previously allocated and assigned memory buffer. As a result, users can leak kernel memory by continuously writing a data to memcg_path DAMOS sysfs file. Fix the leak by deallocating the previously set memory buffer. Link: https://lkml.kernel.org/r/20250619183608.6647-2-sj@kernel.org Fixes: 7ee161f18b5d ("mm/damon/sysfs-schemes: implement filter directory") Signed-off-by: SeongJae Park Cc: Shuah Khan Cc: [6.3.x] Signed-off-by: Andrew Morton --- diff --git a/mm/damon/sysfs-schemes.c b/mm/damon/sysfs-schemes.c index 0f6c9e1fec0b..30ae7518ffbf 100644 --- a/mm/damon/sysfs-schemes.c +++ b/mm/damon/sysfs-schemes.c @@ -472,6 +472,7 @@ static ssize_t memcg_path_store(struct kobject *kobj, return -ENOMEM; strscpy(path, buf, count + 1); + kfree(filter->memcg_path); filter->memcg_path = path; return count; }