> From: Pablo Neira Ayuso [mailto:pablo@xxxxxxxxxxxxx] > On Fri, Apr 14, 2017 at 09:13:40AM +0800, gfree.wind@xxxxxxxxxxx wrote: > > From: Gao Feng <fgao@xxxxxxxxxx> > > > > The function ctnl_untimeout is used to untimeout every conntrack which > > is using the timeout. But it is necessary to add one barrier > > synchronize_rcu because of racing. Maybe one conntrack has already > > owned this timeout, but it is not inserted into unconfirmed list or > > the hash list, when ctnl_untimeout untimeout the conntracks > > > > Let me describe it with a call path > > CPU1 CPU2 > > alloc new conn > > add timeout ext > > ctnl_timeout_try_del > > untimeout all conns in list > > kfree_rcu. > > conn is confirmed. > > Then this confirmed conn gets a timeout_ext->timeout == NULL since > ctnl_untimeout() is called first. The new conn gets the timeout_ext->timeout before ctnl_untimeout, when add the timeout ext. Then ctnl_untimeout happens before the new conn is inserted into unconfirmed list. It could not reset the timeout pointer of new conn to NULL. Maybe I should add the "insert unconfirm list" in the call path. I could not understand why the conn gets one NULL pointer, not invalid pointer in this case. Regards Feng -- To unsubscribe from this list: send the line "unsubscribe netfilter-devel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
