[3.13.y.z extended stable] Patch "Bluetooth: Avoid use of session socket after the session gets freed" has been added to staging queue

[Kamal Mostafa]

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

    Bluetooth: Avoid use of session socket after the session gets freed

to the linux-3.13.y-queue branch of the 3.13.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-3.13.y-queue

This patch is scheduled to be released in version 3.13.11.7.

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

For more information about the 3.13.y.z tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Kamal

------

>From baedce08ab71ad5fd76ebbcdf5c13077d680736f Mon Sep 17 00:00:00 2001
From: Vignesh Raman <Vignesh_Raman at mentor.com>
Date: Tue, 22 Jul 2014 19:24:25 +0530
Subject: Bluetooth: Avoid use of session socket after the session gets freed

commit 32333edb82fb2009980eefc5518100068147ab82 upstream.

The commits 08c30aca9e698faddebd34f81e1196295f9dc063 "Bluetooth: Remove
RFCOMM session refcnt" and 8ff52f7d04d9cc31f1e81dcf9a2ba6335ed34905
"Bluetooth: Return RFCOMM session ptrs to avoid freed session"
allow rfcomm_recv_ua and rfcomm_session_close to delete the session
(and free the corresponding socket) and propagate NULL session pointer
to the upper callers.

Additional fix is required to terminate the loop in rfcomm_process_rx
function to avoid use of freed 'sk' memory.

The issue is only reproducible with kernel option CONFIG_PAGE_POISONING
enabled making freed memory being changed and filled up with fixed char
value used to unmask use-after-free issues.

Signed-off-by: Vignesh Raman <Vignesh_Raman at mentor.com>
Signed-off-by: Vitaly Kuzmichev <Vitaly_Kuzmichev at mentor.com>
Acked-by: Dean Jenkins <Dean_Jenkins at mentor.com>
Signed-off-by: Marcel Holtmann <marcel at holtmann.org>
Signed-off-by: Kamal Mostafa <kamal at canonical.com>
---
 net/bluetooth/rfcomm/core.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/net/bluetooth/rfcomm/core.c b/net/bluetooth/rfcomm/core.c
index facd8a7..b088651 100644
--- a/net/bluetooth/rfcomm/core.c
+++ b/net/bluetooth/rfcomm/core.c
@@ -1859,10 +1859,13 @@ static struct rfcomm_session *rfcomm_process_rx(struct rfcomm_session *s)
 	/* Get data directly from socket receive queue without copying it. */
 	while ((skb = skb_dequeue(&sk->sk_receive_queue))) {
 		skb_orphan(skb);
-		if (!skb_linearize(skb))
+		if (!skb_linearize(skb)) {
 			s = rfcomm_recv_frame(s, skb);
-		else
+			if (!s)
+				break;
+		} else {
 			kfree_skb(skb);
+		}
 	}

 	if (s && (sk->sk_state == BT_CLOSED))
--
1.9.1