Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit 9c936e3f authored by Linus Lüssing's avatar Linus Lüssing Committed by Antonio Quartulli
Browse files

batman-adv: Make MCAST capability changes atomic 



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: 60432d75 ("batman-adv: Announce new capability via multicast TVLV")
Signed-off-by: default avatarLinus Lüssing <linus.luessing@c0d3.blue>
Signed-off-by: default avatarMarek Lindner <mareklindner@neomailbox.ch>
Signed-off-by: default avatarAntonio Quartulli <antonio@meshcoding.com>
parent ac4eebd4

net/batman-adv/multicast.c

+10 −8
Original line number Diff line number Diff line
@@ -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_handler_v1(struct batadv_priv *bat_priv, 
	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 batadv_orig_node *orig) 
{

	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);

net/batman-adv/types.h

+1 −1
Original line number Diff line number Diff line
@@ -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,

};



/**