quota: Fix memory leak when handling corrupted quota file

When checking corrupted quota file we can bail out and leak allocated
info structure. Properly free info structure on error return.

Reported-by: syzbot+77779c9b52ab78154b08@syzkaller.appspotmail.com
Fixes: 11c514a99b ("quota: Sanity-check quota file headers on load")
Signed-off-by: Jan Kara <jack@suse.cz>

fs/quota/quota_v2.c

@@ -164,19 +164,24 @@ static int v2_read_file_info(struct super_block *sb, int type)
 		quota_error(sb, "Number of blocks too big for quota file size (%llu > %llu).",
 		    (loff_t)qinfo->dqi_blocks << qinfo->dqi_blocksize_bits,
 		    i_size_read(sb_dqopt(sb)->files[type]));
-		goto out;
+		goto out_free;
 	}
 	if (qinfo->dqi_free_blk >= qinfo->dqi_blocks) {
 		quota_error(sb, "Free block number too big (%u >= %u).",
 			    qinfo->dqi_free_blk, qinfo->dqi_blocks);
-		goto out;
+		goto out_free;
 	}
 	if (qinfo->dqi_free_entry >= qinfo->dqi_blocks) {
 		quota_error(sb, "Block with free entry too big (%u >= %u).",
 			    qinfo->dqi_free_entry, qinfo->dqi_blocks);
-		goto out;
+		goto out_free;
 	}
 	ret = 0;
+out_free:
+	if (ret) {
+		kfree(info->dqi_priv);
+		info->dqi_priv = NULL;
+	}
 out:
 	up_read(&dqopt->dqio_sem);
 	return ret;