[PATCH 5.1 088/128] ext4: avoid drop reference to iloc.bh twice

[Greg Kroah-Hartman]

From: Pan Bian <bianpan2...@163.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 <bianpan2...@163.com>
Signed-off-by: Theodore Ts'o <ty...@mit.edu>
Reviewed-by: Jan Kara <j...@suse.cz>
Cc: sta...@kernel.org
Signed-off-by: Greg Kroah-Hartman <gre...@linuxfoundation.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);