> -----Original Message----- > From: Pablo Neira Ayuso [mailto:pablo@xxxxxxxxxxxxx] > On Thu, Apr 06, 2017 at 07:09:09PM +0800, gfree.wind@xxxxxxxxxxx wrote: > > > > 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 > > This object is released via kfree_rcu(). > > You have to describe better the race scenario. 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. As the show above, when cpu2 untimeout all conns in list, the new conn of cpu1 is not confirmed. The new conn still owns the timeout pointer. After the timeout mem is freed really, it points to one invalid mem. 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
