linux-kernel - [PATCH] ext4: Fix handle refcount leak in ext4_write

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Date:   Wed,  8 Sep 2021 15:06:40 +0800
From:   Chenyuan Mi <cymi20@...an.edu.cn>
To:     unlisted-recipients:; (no To-header on input)
Cc:     yuanxzhang@...an.edu.cn, Chenyuan Mi <cymi20@...an.edu.cn>,
        Xiyu Yang <xiyuyang19@...an.edu.cn>,
        Xin Tan <tanxin.ctf@...il.com>,
        "Theodore Ts'o" <tytso@....edu>,
        Andreas Dilger <adilger.kernel@...ger.ca>,
        linux-ext4@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH] ext4: Fix handle refcount leak in ext4_write_begin()

The reference counting issue happens when ret is zero,
the function forgets to decrease the refcount of handle
increased by ext4_journal_start().

Fix this issue by using ext4_journal_stop() to decrease
the refcount of handle.

Signed-off-by: Chenyuan Mi <cymi20@...an.edu.cn>
Signed-off-by: Xiyu Yang <xiyuyang19@...an.edu.cn>
Signed-off-by: Xin Tan <tanxin.ctf@...il.com>
---
 fs/ext4/inode.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index d18852d6029c..90c57d8e3de1 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -1249,6 +1249,7 @@ static int ext4_write_begin(struct file *file, struct address_space *mapping,
 		put_page(page);
 		return ret;
 	}
+	ext4_journal_stop(handle);
 	*pagep = page;
 	return ret;
 }
-- 
2.17.1