ext4: avoid drop reference to iloc.bh twice

BugLink: https://bugs.launchpad.net/bugs/1836614
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@163.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Reviewed-by: Jan Kara <jack@suse.cz>
Cc: stable@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Stefan Bader <stefan.bader@canonical.com>
Signed-off-by: Kleber Sacilotto de Souza <kleber.souza@canonical.com>

diff --git a/fs/ext4/resize.c b/fs/ext4/resize.c
index 830b2cf898cf945f7a326320caf380887ad36dd4..02d90043020ff5afcd531b1d2ec10aa450d2bde7 100644 (file)
--- a/fs/ext4/resize.c
+++ b/fs/ext4/resize.c
@@ -874,6 +874,7 @@ static int add_new_gdb(handle_t *handle, struct inode *inode,
        err = ext4_handle_dirty_metadata(handle, NULL, gdb_bh);
        if (unlikely(err)) {
                ext4_std_error(sb, err);
+               iloc.bh = NULL;
                goto errout;
        }
        brelse(dind);