udf: Fix BUG on corrupted inode

When inode is corrupted so that extent type is invalid, some functions
(such as udf_truncate_extents()) will just BUG. Check that extent type
is valid when loading the inode to memory.
Reported-by: Anatoly Trosinenko <anatoly.trosinenko@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>

fs/udf/inode.c

@@ -1357,6 +1357,12 @@ static int udf_read_inode(struct inode *inode, bool hidden_inode)
 
 	iinfo->i_alloc_type = le16_to_cpu(fe->icbTag.flags) &
 							ICBTAG_FLAG_AD_MASK;
+	if (iinfo->i_alloc_type != ICBTAG_FLAG_AD_SHORT &&
+	    iinfo->i_alloc_type != ICBTAG_FLAG_AD_LONG &&
+	    iinfo->i_alloc_type != ICBTAG_FLAG_AD_IN_ICB) {
+		ret = -EIO;
+		goto out;
+	}
 	iinfo->i_unique = 0;
 	iinfo->i_lenEAttr = 0;
 	iinfo->i_lenExtents = 0;