linux-kernel - [PATCH 3.13.y-ckt 013/122] udf: Check length of extended attributes and allocation descriptors

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Message-Id: <1434580149-3095-14-git-send-email-kamal@canonical.com>
Date:	Wed, 17 Jun 2015 15:27:20 -0700
From:	Kamal Mostafa <kamal@...onical.com>
To:	linux-kernel@...r.kernel.org, stable@...r.kernel.org,
	kernel-team@...ts.ubuntu.com
Cc:	Jan Kara <jack@...e.cz>,
	Luis Henriques <luis.henriques@...onical.com>,
	Kamal Mostafa <kamal@...onical.com>
Subject: [PATCH 3.13.y-ckt 013/122] udf: Check length of extended attributes and allocation descriptors

3.13.11-ckt22 -stable review patch.  If anyone has any objections, please let me know.

------------------

From: Jan Kara <jack@...e.cz>

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@...g.uio.no>
Signed-off-by: Jan Kara <jack@...e.cz>
Reference: CVE-2015-4167
BugLink: https://bugs.launchpad.net/bugs/1462173
[ luis: used Ben's backport to 3.16:
  - use make_bad_inode() instead of returning error ]
Signed-off-by: Luis Henriques <luis.henriques@...onical.com>
Signed-off-by: Kamal Mostafa <kamal@...onical.com>
---
 fs/udf/inode.c | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/fs/udf/inode.c b/fs/udf/inode.c
index 8aa2b1b..cfdbbfd 100644
--- a/fs/udf/inode.c
+++ b/fs/udf/inode.c
@@ -1480,6 +1480,19 @@ reread:
 		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) {
 		/*
-- 
1.9.1

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