linux-kernel - [PATCH 4.19 069/105] ext4: avoid drop reference to iloc.bh twice

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Date:   Mon, 20 May 2019 14:14:15 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Pan Bian <bianpan2016@....com>,
        Theodore Tso <tytso@....edu>, Jan Kara <jack@...e.cz>,
        stable@...nel.org
Subject: [PATCH 4.19 069/105] ext4: avoid drop reference to iloc.bh twice

From: Pan Bian <bianpan2016@....com>

commit 8c380ab4b7b59c0c602743810be1b712514eaebc upstream.

The reference to iloc.bh has been dropped in ext4_mark_iloc_dirty.
However, the reference is dropped again if error occurs during
ext4_handle_dirty_metadata, which may result in use-after-free bugs.

Fixes: fb265c9cb49e("ext4: add ext4_sb_bread() to disambiguate ENOMEM cases")
Signed-off-by: Pan Bian <bianpan2016@....com>
Signed-off-by: Theodore Ts'o <tytso@....edu>
Reviewed-by: Jan Kara <jack@...e.cz>
Cc: stable@...nel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

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

--- a/fs/ext4/resize.c
+++ b/fs/ext4/resize.c
@@ -874,6 +874,7 @@ static int add_new_gdb(handle_t *handle,
 	err = ext4_handle_dirty_metadata(handle, NULL, gdb_bh);
 	if (unlikely(err)) {
 		ext4_std_error(sb, err);
+		iloc.bh = NULL;
 		goto errout;
 	}
 	brelse(dind);