erofs: fix incorrect early exits for invalid metabox-enabled images

[ Upstream commit 643575d ]

Crafted EROFS images with metadata compression enabled can trigger
incorrect early returns, leading to folio reference leaks.

However, this does not cause system crashes or other severe issues.

Fixes: 4140913 ("erofs: implement metadata compression")
Cc: stable@kernel.org
Reviewed-by: Hongbo Li <lihongbo22@huawei.com>
Reviewed-by: Chao Yu <chao@kernel.org>
Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>

Author: hsiangkao

fs/erofs/super.c

@@ -330,12 +330,13 @@ static int erofs_read_superblock(struct super_block *sb)
 	}
 	sbi->packed_nid = le64_to_cpu(dsb->packed_nid);
 	if (erofs_sb_has_metabox(sbi)) {
+		ret = -EFSCORRUPTED;
 		if (sbi->sb_size <= offsetof(struct erofs_super_block,
 					     metabox_nid))
-			return -EFSCORRUPTED;
+			goto out;
 		sbi->metabox_nid = le64_to_cpu(dsb->metabox_nid);
 		if (sbi->metabox_nid & BIT_ULL(EROFS_DIRENT_NID_METABOX_BIT))
-			return -EFSCORRUPTED;	/* self-loop detection */
+			goto out;		/* self-loop detection */
 	}
 	sbi->inos = le64_to_cpu(dsb->inos);