ext4: avoid drop reference to iloc.bh twice

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

diff --git a/fs/ext4/resize.c b/fs/ext4/resize.c
index e7ae26e36c9c119a0b8b025e57914ba411b38ac5..4d5c0fc9d23a78533ed6fcca349f03550e1c2521 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);