udf: Check length of extended attributes and allocation descriptors

commit 23b133bdc452aa441fcb9b82cbf6dd05cfd342d0 upstream.

Check length of extended attributes and allocation descriptors when
loading inodes from disk. Otherwise corrupted filesystems could confuse
the code and make the kernel oops.

Reported-by: Carl Henrik Lunde <chlunde@ping.uio.no>
Signed-off-by: Jan Kara <jack@suse.cz>
[bwh: Backported to 3.16: use make_bad_inode() instead of returning error]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
Signed-off-by: Luis Henriques <luis.henriques@canonical.com>

diff --git a/fs/udf/inode.c b/fs/udf/inode.c
index c7a5753dc4ec4db6e38fa9f2ba67a7b0a2fbe64e..9a46e23cb769d48a179af886a31d435fa17c45a4 100644 (file)
--- a/fs/udf/inode.c
+++ b/fs/udf/inode.c
@@ -1494,6 +1494,19 @@ static void udf_fill_inode(struct inode *inode, struct buffer_head *bh)
                iinfo->i_checkpoint = le32_to_cpu(efe->checkpoint);
        }
 
+       /*
+        * Sanity check length of allocation descriptors and extended attrs to
+        * avoid integer overflows
+        */
+       if (iinfo->i_lenEAttr > bs || iinfo->i_lenAlloc > bs) {
+               make_bad_inode(inode);
+               return;
+       }
+       /* Now do exact checks */
+       if (udf_file_entry_alloc_offset(inode) + iinfo->i_lenAlloc > bs) {
+               make_bad_inode(inode);
+               return;
+       }
        /* Sanity checks for files in ICB so that we don't get confused later */
        if (iinfo->i_alloc_type == ICBTAG_FLAG_AD_IN_ICB) {
                /*