Re: [PATCH] igmp: fix ip_mc_sf_allow race [v3]
From: Eric Dumazet <hidden>
Date: 2010-01-05 22:37:21
Le 05/01/2010 21:52, Flavio Leitner a écrit :
Almost all igmp functions accessing inet->mc_list are protected by rtnl_lock(), but there is one exception which is ip_mc_sf_allow(), so there is a chance of either ip_mc_drop_socket or ip_mc_leave_group remove an entry while ip_mc_sf_allow is running causing a crash. Signed-off-by: Flavio Leitner <redacted>
Acked-by: Eric Dumazet <redacted>
Small notes : in ip_mc_drop_socket()
// rcu_read_lock()/unlock() seems not really needed here, we only want to avoid
//the fill rtnlçlock() in case this socket have a NULL mc_list.
rcu_read_lock();
if (rcu_dereference(inet->mc_list) == NULL) {
rcu_read_unlock();
return;
}
rcu_read_unlock();
rtnl_lock();
while ((iml = rcu_dereference(inet->mc_list)) != NULL) {
rcu_dereference() is not really needed here, since you own RTNL