[PATCH] btrfs: Fix memory leak in __add_inode_ref()

Jianglei Nie
2021-12-09T07:12:36Z

Line 1169 (#3) allocates a memory chunk for victim_name by kmalloc(),
but when the function returns in line 1184 (#4) victim_name allcoated
by line 1169 (#3) is not freed, which will lead to a memory leak.
There is a similar snippet of code in this function as allocating a memory
chunk for victim_name in line 1104 (#1) as well as releasing the memory
in line 1116 (#2).

We should kfree() victim_name when the return value of backref_in_log()
is less than zero and before the function returns in line 1184 (#4).

1057 static inline int __add_inode_ref(struct btrfs_trans_handle *trans,
1058 struct btrfs_root *root,
1059 struct btrfs_path *path,
1060 struct btrfs_root *log_root,
1061 struct btrfs_inode *dir,
1062 struct btrfs_inode *inode,
1063 u64 inode_objectid, u64 parent_objectid,
1064 u64 ref_index, char *name, int namelen,
1065 int *search_done)
1066 {

1104 victim_name = kmalloc(victim_name_len, GFP_NOFS);
// #1: kmalloc (victim_name-1)
1105 if (!victim_name)
1106 return -ENOMEM;

1112 ret = backref_in_log(log_root, &search_key,
1113 parent_objectid, victim_name,
1114 victim_name_len);
1115 if (ret < 0) {
1116 kfree(victim_name); // #2: kfree (victim_name-1)
1117 return ret;
1118 } else if (!ret) {

1169 victim_name = kmalloc(victim_name_len, GFP_NOFS);
// #3: kmalloc (victim_name-2)
1170 if (!victim_name)
1171 return -ENOMEM;

1180 ret = backref_in_log(log_root, &search_key,
1181 parent_objectid, victim_name,
1182 victim_name_len);
1183 if (ret < 0) {
1184 return ret; // #4: missing kfree (victim_name-2)
1185 } else if (!ret) {

1241 return 0;
1242 }

Signed-off-by: Jianglei Nie <niejianglei2021@163.com>
---
fs/btrfs/tree-log.c | 1 +
1 file changed, 1 insertion(+)

diff --git a/fs/btrfs/tree-log.c b/fs/btrfs/tree-log.c
index 8ab33caf016f..d373fec55521 100644
--- a/fs/btrfs/tree-log.c
+++ b/fs/btrfs/tree-log.c
@@ -1181,6 +1181,7 @@ static inline int __add_inode_ref(struct btrfs_trans_handle *trans,
parent_objectid, victim_name,
victim_name_len);
if (ret < 0) {
+ kfree(victim_name);
return ret;
} else if (!ret) {
ret = -ENOENT;
--
2.25.1