[3.11.y.z extended stable] Patch "radiotap: fix bitmap-end-finding 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

    radiotap: fix bitmap-end-finding buffer overrun

to the linux-3.11.y-queue branch of the 3.11.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-3.11.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 3.11.y.z tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Luis

------

>From 7898ebaa7102d73ffc7c49b1c79419f99edd4705 Mon Sep 17 00:00:00 2001
From: Johannes Berg <johannes.berg at intel.com>
Date: Mon, 16 Dec 2013 12:04:36 +0100
Subject: radiotap: fix bitmap-end-finding buffer overrun

commit bd02cd2549cfcdfc57cb5ce57ffc3feb94f70575 upstream.

Evan Huus found (by fuzzing in wireshark) that the radiotap
iterator code can access beyond the length of the buffer if
the first bitmap claims an extension but then there's no
data at all. Fix this.

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 | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/net/wireless/radiotap.c b/net/wireless/radiotap.c
index a271c27..722da61 100644
--- a/net/wireless/radiotap.c
+++ b/net/wireless/radiotap.c
@@ -124,6 +124,10 @@ int ieee80211_radiotap_iterator_init(
 	/* find payload start allowing for extended bitmap(s) */

 	if (iterator->_bitmap_shifter & (1<<IEEE80211_RADIOTAP_EXT)) {
+		if ((unsigned long)iterator->_arg -
+		    (unsigned long)iterator->_rtheader + sizeof(uint32_t) >
+		    (unsigned long)iterator->_max_length)
+			return -EINVAL;
 		while (get_unaligned_le32(iterator->_arg) &
 					(1 << IEEE80211_RADIOTAP_EXT)) {
 			iterator->_arg += sizeof(uint32_t);
--
1.8.3.2