udf: Verify i_size when loading inode

Verify that inode size is sane when loading inode with data stored in
ICB. Otherwise we may get confused later when working with the inode and
inode size is too big.

CC: stable@vger.kernel.org
Reported-by: Carl Henrik Lunde <chlunde@ping.uio.no>
Signed-off-by: Jan Kara <jack@suse.cz>

fs/udf/inode.c

@@ -1489,6 +1489,20 @@ static int udf_read_inode(struct inode *inode, bool hidden_inode)
 	}
 	inode->i_generation = iinfo->i_unique;
 
+	/* Sanity checks for files in ICB so that we don't get confused later */
+	if (iinfo->i_alloc_type == ICBTAG_FLAG_AD_IN_ICB) {
+		/*
+		 * For file in ICB data is stored in allocation descriptor
+		 * so sizes should match
+		 */
+		if (iinfo->i_lenAlloc != inode->i_size)
+			goto out;
+		/* File in ICB has to fit in there... */
+		if (inode->i_size > inode->i_sb->s_blocksize -
+					udf_file_entry_alloc_offset(inode))
+			goto out;
+	}
+
 	switch (fe->icbTag.fileType) {
 	case ICBTAG_FILE_TYPE_DIRECTORY:
 		inode->i_op = &udf_dir_inode_operations;