Patch "batman-adv: Make MCAST capability changes atomic" has been added to the 4.2-stable tree

[<gregkh@linuxfoundation.org>]

This is a note to let you know that I've just added the patch titled

    batman-adv: Make MCAST capability changes atomic

to the 4.2-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     batman-adv-make-mcast-capability-changes-atomic.patch
and it can be found in the queue-4.2 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From 9c936e3f4c4fad07abb6c082a89508b8f724c88f Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Linus=20L=C3=BCssing?= <linus.luessing@c0d3.blue>
Date: Tue, 16 Jun 2015 17:10:25 +0200
Subject: batman-adv: Make MCAST capability changes atomic
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From: =?UTF-8?q?Linus=20L=C3=BCssing?= <linus.luessing@c0d3.blue>

commit 9c936e3f4c4fad07abb6c082a89508b8f724c88f upstream.

Bitwise OR/AND assignments in C aren't guaranteed to be atomic. One
OGM handler might undo the set/clear of a specific bit from another
handler run in between.

Fix this by using the atomic set_bit()/clear_bit()/test_bit() functions.

Fixes: 60432d756cf0 ("batman-adv: Announce new capability via multicast TVLV")
Signed-off-by: Linus Lüssing <linus.luessing@c0d3.blue>
Signed-off-by: Marek Lindner <mareklindner@neomailbox.ch>
Signed-off-by: Antonio Quartulli <antonio@meshcoding.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 net/batman-adv/multicast.c |   18 ++++++++++--------
 net/batman-adv/types.h     |    2 +-
 2 files changed, 11 insertions(+), 9 deletions(-)

--- a/net/batman-adv/multicast.c
+++ b/net/batman-adv/multicast.c
@@ -19,6 +19,7 @@
 #include "main.h"
 
 #include <linux/atomic.h>
+#include <linux/bitops.h>
 #include <linux/byteorder/generic.h>
 #include <linux/errno.h>
 #include <linux/etherdevice.h>
@@ -697,29 +698,30 @@ static void batadv_mcast_tvlv_ogm_handle
 	uint8_t mcast_flags = BATADV_NO_FLAGS;
 	bool orig_initialized;
 
-	orig_initialized = orig->capa_initialized & BATADV_ORIG_CAPA_HAS_MCAST;
+	orig_initialized = test_bit(BATADV_ORIG_CAPA_HAS_MCAST,
+				    &orig->capa_initialized);
 
 	/* If mcast support is turned on decrease the disabled mcast node
 	 * counter only if we had increased it for this node before. If this
 	 * is a completely new orig_node no need to decrease the counter.
 	 */
 	if (orig_mcast_enabled &&
-	    !(orig->capabilities & BATADV_ORIG_CAPA_HAS_MCAST)) {
+	    !test_bit(BATADV_ORIG_CAPA_HAS_MCAST, &orig->capabilities)) {
 		if (orig_initialized)
 			atomic_dec(&bat_priv->mcast.num_disabled);
-		orig->capabilities |= BATADV_ORIG_CAPA_HAS_MCAST;
+		set_bit(BATADV_ORIG_CAPA_HAS_MCAST, &orig->capabilities);
 	/* If mcast support is being switched off or if this is an initial
 	 * OGM without mcast support then increase the disabled mcast
 	 * node counter.
 	 */
 	} else if (!orig_mcast_enabled &&
-		   (orig->capabilities & BATADV_ORIG_CAPA_HAS_MCAST ||
+		   (test_bit(BATADV_ORIG_CAPA_HAS_MCAST, &orig->capabilities) ||
 		    !orig_initialized)) {
 		atomic_inc(&bat_priv->mcast.num_disabled);
-		orig->capabilities &= ~BATADV_ORIG_CAPA_HAS_MCAST;
+		clear_bit(BATADV_ORIG_CAPA_HAS_MCAST, &orig->capabilities);
 	}
 
-	orig->capa_initialized |= BATADV_ORIG_CAPA_HAS_MCAST;
+	set_bit(BATADV_ORIG_CAPA_HAS_MCAST, &orig->capa_initialized);
 
 	if (orig_mcast_enabled && tvlv_value &&
 	    (tvlv_value_len >= sizeof(mcast_flags)))
@@ -763,8 +765,8 @@ void batadv_mcast_purge_orig(struct bata
 {
 	struct batadv_priv *bat_priv = orig->bat_priv;
 
-	if (!(orig->capabilities & BATADV_ORIG_CAPA_HAS_MCAST) &&
-	    orig->capa_initialized & BATADV_ORIG_CAPA_HAS_MCAST)
+	if (!test_bit(BATADV_ORIG_CAPA_HAS_MCAST, &orig->capabilities) &&
+	    test_bit(BATADV_ORIG_CAPA_HAS_MCAST, &orig->capa_initialized))
 		atomic_dec(&bat_priv->mcast.num_disabled);
 
 	batadv_mcast_want_unsnoop_update(bat_priv, orig, BATADV_NO_FLAGS);
--- a/net/batman-adv/types.h
+++ b/net/batman-adv/types.h
@@ -316,7 +316,7 @@ enum batadv_orig_capabilities {
 	BATADV_ORIG_CAPA_HAS_DAT,
 	BATADV_ORIG_CAPA_HAS_NC,
 	BATADV_ORIG_CAPA_HAS_TT,
-	BATADV_ORIG_CAPA_HAS_MCAST = BIT(3),
+	BATADV_ORIG_CAPA_HAS_MCAST,
 };
 
 /**


Patches currently in stable-queue which might be from linus.luessing@c0d3.blue are

queue-4.2/batman-adv-fix-potential-synchronization-issues-in-mcast-tvlv-handler.patch
queue-4.2/batman-adv-make-tt-capability-changes-atomic.patch
queue-4.2/batman-adv-make-dat-capability-changes-atomic.patch
queue-4.2/batman-adv-make-nc-capability-changes-atomic.patch
queue-4.2/batman-adv-fix-potentially-broken-skb-network-header-access.patch
queue-4.2/batman-adv-make-mcast-capability-changes-atomic.patch