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authorMarek Lindner <lindner_marek@yahoo.de>2011-02-18 12:28:10 +0000
committerMarek Lindner <lindner_marek@yahoo.de>2011-03-05 12:52:01 +0100
commit7b36e8eef989fc59535b4f1d3fc0f83afaf419d4 (patch)
treef0900101542966e0655ca5f115b5b0bc409b1e74 /net/batman-adv/gateway_client.c
parent7aadf889e897155c45cda230d2a6701ad1fbff61 (diff)
downloadlinux-7b36e8eef989fc59535b4f1d3fc0f83afaf419d4.tar.bz2
batman-adv: Correct rcu refcounting for orig_node
It might be possible that 2 threads access the same data in the same rcu grace period. The first thread calls call_rcu() to decrement the refcount and free the data while the second thread increases the refcount to use the data. To avoid this race condition all refcount operations have to be atomic. Reported-by: Sven Eckelmann <sven@narfation.org> Signed-off-by: Marek Lindner <lindner_marek@yahoo.de>
Diffstat (limited to 'net/batman-adv/gateway_client.c')
-rw-r--r--net/batman-adv/gateway_client.c6
1 files changed, 4 insertions, 2 deletions
diff --git a/net/batman-adv/gateway_client.c b/net/batman-adv/gateway_client.c
index 41eba8a660f5..3cc43558cf9c 100644
--- a/net/batman-adv/gateway_client.c
+++ b/net/batman-adv/gateway_client.c
@@ -53,9 +53,11 @@ void *gw_get_selected(struct bat_priv *bat_priv)
goto out;
orig_node = curr_gateway_tmp->orig_node;
+ if (!orig_node)
+ goto out;
- if (orig_node)
- kref_get(&orig_node->refcount);
+ if (!atomic_inc_not_zero(&orig_node->refcount))
+ orig_node = NULL;
out:
rcu_read_unlock();