udf: Verify i_size when loading inode

commit e159332b upstream.

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.
Reported-by: Carl Henrik Lunde <chlunde@ping.uio.no>
Signed-off-by: Jan Kara <jack@suse.cz>
[ luis: backported to 3.16:
  - Adjusted exit paths as commit 6d3d5e86 ("udf: Make udf_read_inode()
    and udf_iget() return error") is not present in 3.16 kernel ]
Signed-off-by: Luis Henriques <luis.henriques@canonical.com>

fs/udf/inode.c

@@ -1496,6 +1496,24 @@ static void udf_fill_inode(struct inode *inode, struct buffer_head *bh)
 		iinfo->i_checkpoint = le32_to_cpu(efe->checkpoint);
 	}
 
+	/* 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) {
+			make_bad_inode(inode);
+			return;
+		}
+		/* File in ICB has to fit in there... */
+		if (inode->i_size > inode->i_sb->s_blocksize -
+					udf_file_entry_alloc_offset(inode)) {
+			make_bad_inode(inode);
+			return;
+		}
+	}
+
 	switch (fe->icbTag.fileType) {
 	case ICBTAG_FILE_TYPE_DIRECTORY:
 		inode->i_op = &udf_dir_inode_operations;