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batman-adv: Make MCAST capability changes atomic

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commit 9c936e3f4c 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: 60432d756c ("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>
This commit is contained in:
Linus Lüssing
2015-06-16 17:10:25 +02:00
committed by Greg Kroah-Hartman
parent 3dd853ed30
commit 8dbeac75e6
2 changed files with 11 additions and 9 deletions
Download Patch File Download Diff File Expand all files Collapse all files

18
net/batman-adv/multicast.c
View File

@@ -15,6 +15,7 @@
* along with this program; if not, see <http://www.gnu.org/licenses/>. * along with this program; if not, see <http://www.gnu.org/licenses/>.
*/ */
#include <linux/bitops.h>
#include "main.h" #include "main.h"
#include "multicast.h" #include "multicast.h"
#include "originator.h" #include "originator.h"
@@ -674,29 +675,30 @@ static void batadv_mcast_tvlv_ogm_handler_v1(struct batadv_priv *bat_priv,
uint8_t mcast_flags = BATADV_NO_FLAGS; uint8_t mcast_flags = BATADV_NO_FLAGS;
bool orig_initialized; 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 /* If mcast support is turned on decrease the disabled mcast node
* counter only if we had increased it for this node before. If this * 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. * is a completely new orig_node no need to decrease the counter.
*/ */
if (orig_mcast_enabled && if (orig_mcast_enabled &&
!(orig->capabilities & BATADV_ORIG_CAPA_HAS_MCAST)) { !test_bit(BATADV_ORIG_CAPA_HAS_MCAST, &orig->capabilities)) {
if (orig_initialized) if (orig_initialized)
atomic_dec(&bat_priv->mcast.num_disabled); 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 /* If mcast support is being switched off or if this is an initial
* OGM without mcast support then increase the disabled mcast * OGM without mcast support then increase the disabled mcast
* node counter. * node counter.
*/ */
} else if (!orig_mcast_enabled && } else if (!orig_mcast_enabled &&
(orig->capabilities & BATADV_ORIG_CAPA_HAS_MCAST || (test_bit(BATADV_ORIG_CAPA_HAS_MCAST, &orig->capabilities) ||
!orig_initialized)) { !orig_initialized)) {
atomic_inc(&bat_priv->mcast.num_disabled); 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 && if (orig_mcast_enabled && tvlv_value &&
(tvlv_value_len >= sizeof(mcast_flags))) (tvlv_value_len >= sizeof(mcast_flags)))
@@ -740,8 +742,8 @@ void batadv_mcast_purge_orig(struct batadv_orig_node *orig)
{ {
struct batadv_priv *bat_priv = orig->bat_priv; struct batadv_priv *bat_priv = orig->bat_priv;
if (!(orig->capabilities & BATADV_ORIG_CAPA_HAS_MCAST) && if (!test_bit(BATADV_ORIG_CAPA_HAS_MCAST, &orig->capabilities) &&
orig->capa_initialized & BATADV_ORIG_CAPA_HAS_MCAST) test_bit(BATADV_ORIG_CAPA_HAS_MCAST, &orig->capa_initialized))
atomic_dec(&bat_priv->mcast.num_disabled); atomic_dec(&bat_priv->mcast.num_disabled);
batadv_mcast_want_unsnoop_update(bat_priv, orig, BATADV_NO_FLAGS); batadv_mcast_want_unsnoop_update(bat_priv, orig, BATADV_NO_FLAGS);

2
net/batman-adv/types.h
View File

@@ -299,7 +299,7 @@ enum batadv_orig_capabilities {
BATADV_ORIG_CAPA_HAS_DAT, BATADV_ORIG_CAPA_HAS_DAT,
BATADV_ORIG_CAPA_HAS_NC, BATADV_ORIG_CAPA_HAS_NC,
BATADV_ORIG_CAPA_HAS_TT, BATADV_ORIG_CAPA_HAS_TT,
BATADV_ORIG_CAPA_HAS_MCAST = BIT(3), BATADV_ORIG_CAPA_HAS_MCAST,
}; };
/** /**