From cca415537244f6102cbb09b5b90db6ae2c953bdd Mon Sep 17 00:00:00 2001
From: Chunguang Xu <brookxu@tencent.com>
Date: Sat, 7 Nov 2020 23:58:18 +0800
Subject: [PATCH] ext4: fix a memory leak of ext4_free_data
Git-commit: cca415537244f6102cbb09b5b90db6ae2c953bdd
Patch-mainline: v5.11-rc1
References: bsc#1182447

When freeing metadata, we will create an ext4_free_data and
insert it into the pending free list.  After the current
transaction is committed, the object will be freed.

ext4_mb_free_metadata() will check whether the area to be freed
overlaps with the pending free list. If true, return directly. At this
time, ext4_free_data is leaked.  Fortunately, the probability of this
problem is small, since it only occurs if the file system is corrupted
such that a block is claimed by more one inode and those inodes are
deleted within a single jbd2 transaction.

Signed-off-by: Chunguang Xu <brookxu@tencent.com>
Link: https://lore.kernel.org/r/1604764698-4269-8-git-send-email-brookxu@tencent.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Cc: stable@kernel.org
Acked-by: Jan Kara <jack@suse.cz>

---
 fs/ext4/mballoc.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c
index 29dfeb043050..77815cd110b2 100644
--- a/fs/ext4/mballoc.c
+++ b/fs/ext4/mballoc.c
@@ -5103,6 +5103,7 @@ ext4_mb_free_metadata(handle_t *handle, struct ext4_buddy *e4b,
 				ext4_group_first_block_no(sb, group) +
 				EXT4_C2B(sbi, cluster),
 				"Block already on to-be-freed list");
+			kmem_cache_free(ext4_free_data_cachep, new_entry);
 			return 0;
 		}
 	}
-- 
2.26.2