[PATCH 5.15 19/83] mm/damon/dbgfs: fix memory leak when using debugfs_lookup()

Greg Kroah-Hartman
2022-10-03T08:41:18Z

From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

commit 1552fd3ef7dbe07208b8ae84a0a6566adf7dfc9d upstream.

When calling debugfs_lookup() the result must have dput() called on it,
otherwise the memory will leak over time. Fix this up by properly calling
dput().

Link: https://lkml.kernel.org/r/20220902191149.112434-1-sj@kernel.org
Fixes: 75c1c2b53c78b ("mm/damon/dbgfs: support multiple contexts")
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: SeongJae Park <sj@kernel.org>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
mm/damon/dbgfs.c | 19 ++++++++++++++-----
1 file changed, 14 insertions(+), 5 deletions(-)

--- a/mm/damon/dbgfs.c
+++ b/mm/damon/dbgfs.c
@@ -443,6 +443,7 @@ static int dbgfs_rm_context(char *name)
struct dentry *root, *dir, **new_dirs;
struct damon_ctx **new_ctxs;
int i, j;
+ int ret = 0;

if (damon_nr_running_ctxs())
return -EBUSY;
@@ -457,14 +458,16 @@ static int dbgfs_rm_context(char *name)

new_dirs = kmalloc_array(dbgfs_nr_ctxs - 1, sizeof(*dbgfs_dirs),
GFP_KERNEL);
- if (!new_dirs)
- return -ENOMEM;
+ if (!new_dirs) {
+ ret = -ENOMEM;
+ goto out_dput;
+ }

new_ctxs = kmalloc_array(dbgfs_nr_ctxs - 1, sizeof(*dbgfs_ctxs),
GFP_KERNEL);
if (!new_ctxs) {
- kfree(new_dirs);
- return -ENOMEM;
+ ret = -ENOMEM;
+ goto out_new_dirs;
}

for (i = 0, j = 0; i < dbgfs_nr_ctxs; i++) {
@@ -484,7 +487,13 @@ static int dbgfs_rm_context(char *name)
dbgfs_ctxs = new_ctxs;
dbgfs_nr_ctxs--;

- return 0;
+ goto out_dput;
+
+out_new_dirs:
+ kfree(new_dirs);
+out_dput:
+ dput(dir);
+ return ret;
}

static ssize_t dbgfs_rm_context_write(struct file *file,