[patch added to the 3.12 stable tree] udf: Check length of extended attributes and allocation descriptors

[Jiri Slaby <jslaby@suse.cz>]

From: Jan Kara <jack@suse.cz>

This patch has been added to the 3.12 stable tree. If you have any
objections, please let us know.

===============

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>
Cc: stable@vger.kernel.org
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
---
 fs/udf/inode.c | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/fs/udf/inode.c b/fs/udf/inode.c
index cbc438e8f406..b0774f245199 100644
--- a/fs/udf/inode.c
+++ b/fs/udf/inode.c
@@ -1493,6 +1493,15 @@ 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)
+		return;
+	/* Now do exact checks */
+	if (udf_file_entry_alloc_offset(inode) + iinfo->i_lenAlloc > bs)
+		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) {
 		/*
-- 
2.4.3