[3.5.y.z extended stable] Patch "wireless: radiotap: fix parsing buffer overrun" has been added to staging queue

[Luis Henriques]

This is a note to let you know that I have just added a patch titled

    wireless: radiotap: fix parsing buffer overrun

to the linux-3.5.y-queue branch of the 3.5.y.z extended stable tree 
which can be found at:

 http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.5.y-queue

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.5.y.z tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Luis

------

>From 9b970e36bd741a35998091ea376c479da9abce60 Mon Sep 17 00:00:00 2001
From: Johannes Berg <johannes.berg at intel.com>
Date: Fri, 11 Oct 2013 14:47:05 +0200
Subject: wireless: radiotap: fix parsing buffer overrun

commit f5563318ff1bde15b10e736e97ffce13be08bc1a upstream.

When parsing an invalid radiotap header, the parser can overrun
the buffer that is passed in because it doesn't correctly check
 1) the minimum radiotap header size
 2) the space for extended bitmaps

The first issue doesn't affect any in-kernel user as they all
check the minimum size before calling the radiotap function.
The second issue could potentially affect the kernel if an skb
is passed in that consists only of the radiotap header with a
lot of extended bitmaps that extend past the SKB. In that case
a read-only buffer overrun by at most 4 bytes is possible.

Fix this by adding the appropriate checks to the parser.

Reported-by: Evan Huus <eapache at gmail.com>
Signed-off-by: Johannes Berg <johannes.berg at intel.com>
Signed-off-by: Luis Henriques <luis.henriques at canonical.com>
---
 net/wireless/radiotap.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/net/wireless/radiotap.c b/net/wireless/radiotap.c
index c4ad795..617a310 100644
--- a/net/wireless/radiotap.c
+++ b/net/wireless/radiotap.c
@@ -95,6 +95,10 @@ int ieee80211_radiotap_iterator_init(
 	struct ieee80211_radiotap_header *radiotap_header,
 	int max_length, const struct ieee80211_radiotap_vendor_namespaces *vns)
 {
+	/* check the radiotap header can actually be present */
+	if (max_length < sizeof(struct ieee80211_radiotap_header))
+		return -EINVAL;
+
 	/* Linux only supports version 0 radiotap format */
 	if (radiotap_header->it_version)
 		return -EINVAL;
@@ -129,7 +133,8 @@ int ieee80211_radiotap_iterator_init(
 			 */

 			if ((unsigned long)iterator->_arg -
-			    (unsigned long)iterator->_rtheader >
+			    (unsigned long)iterator->_rtheader +
+			    sizeof(uint32_t) >
 			    (unsigned long)iterator->_max_length)
 				return -EINVAL;
 		}
--
1.8.3.2