linux-ext4 - [PATCH 8/8] ext4: fix a memory leak of ext4_free

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Date:   Wed, 21 Oct 2020 17:15:28 +0800
From:   Chunguang Xu <brookxu.cn@...il.com>
To:     tytso@....edu, adilger.kernel@...ger.ca
Cc:     linux-ext4@...r.kernel.org
Subject: [PATCH 8/8] ext4: fix a memory leak of ext4_free_data

From: Chunguang Xu <brookxu@...cent.com>

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 relatively small, maybe we
should fix this problem.

Signed-off-by: Chunguang Xu <brookxu@...cent.com>
---
 fs/ext4/mballoc.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c
index 2b1bc6c..3af4903 100644
--- a/fs/ext4/mballoc.c
+++ b/fs/ext4/mballoc.c
@@ -5146,6 +5146,7 @@ int ext4_metadata_block_overlaps(struct super_block *sb,
 				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;
 		}
 	}
-- 
1.8.3.1