[PATCH v2] mm/damon/dbgfs: fix memory leak when using

[SeongJae Park]

From: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

debugfs_lookup()
Date: Fri,  2 Sep 2022 14:56:31 +0200	[thread overview]
Message-ID: <20220902125631.128329-1-gregkh@xxxxxxxxxxxxxxxxxxx> (raw)

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().

Fixes: 75c1c2b53c78b ("mm/damon/dbgfs: support multiple contexts")
Cc: <stable@xxxxxxxxxxxxxxx> # 5.15.x
Cc: SeongJae Park <sj@xxxxxxxxxx>
Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Cc: damon@xxxxxxxxxxxxxxx
Cc: linux-mm@xxxxxxxxx
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: SeongJae Park <sj@xxxxxxxxxx>
---
Changes from v1
(https://lore.kernel.org/damon/20220902125631.128329-1-gregkh@xxxxxxxxxxxxxxxxxxx/)
- Call dput() for failure-return case (Andrew Morton)

 mm/damon/dbgfs.c | 19 ++++++++++++++-----
 1 file changed, 14 insertions(+), 5 deletions(-)

diff --git a/mm/damon/dbgfs.c b/mm/damon/dbgfs.c
index 3b55a1b219b5..652a94deafe3 100644
--- a/mm/damon/dbgfs.c
+++ b/mm/damon/dbgfs.c
@@ -884,6 +884,7 @@ 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;
@@ -898,14 +899,16 @@ 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++) {
@@ -925,7 +928,13 @@ 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,
-- 
2.25.1