linux-kernel - [PATCH -next 5/6] ext4: avoid to double free s_mmp

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Date:   Mon, 6 Sep 2021 22:47:53 +0800
From:   Ye Bin <yebin10@...wei.com>
To:     <tytso@....edu>, <adilger.kernel@...ger.ca>,
        <linux-ext4@...r.kernel.org>
CC:     <linux-kernel@...r.kernel.org>, <jack@...e.cz>,
        Ye Bin <yebin10@...wei.com>
Subject: [PATCH -next 5/6] ext4: avoid to double free s_mmp_bh

If call read_mmp_block failed then s_mmp_bh will be freed in read_mmp_block.
Kmmpd wait to be killed, ext4_stop_mmpd stop kmmpd and also release s_mmp_bh.
To avoid double free, just set EXT4_SB(sb)->s_mmp_bh with NULL.

Signed-off-by: Ye Bin <yebin10@...wei.com>
---
 fs/ext4/mmp.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/fs/ext4/mmp.c b/fs/ext4/mmp.c
index 2a1473e4a9de..eed854bb6194 100644
--- a/fs/ext4/mmp.c
+++ b/fs/ext4/mmp.c
@@ -218,6 +218,7 @@ static int kmmpd(void *data)
 				ext4_error_err(sb, -retval,
 					       "error reading MMP data: %d",
 					       retval);
+				EXT4_SB(sb)->s_mmp_bh = NULL;
 				goto wait_to_exit;
 			}
 
-- 
2.31.1