linux-kernel - [PATCH] btrfs: Fix memory leak in __add_inode

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Message-Id: <20211209065631.124586-1-niejianglei2021@163.com>
Date:   Thu,  9 Dec 2021 14:56:31 +0800
From:   Jianglei Nie <niejianglei2021@....com>
To:     clm@...com, josef@...icpanda.com, dsterba@...e.com
Cc:     linux-btrfs@...r.kernel.org, linux-kernel@...r.kernel.org,
        Jianglei Nie <niejianglei2021@....com>
Subject: [PATCH] btrfs: Fix memory leak in __add_inode_ref()

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@....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