On Sat, Aug 13, 2016 at 11:13:01PM +0800, Liping Zhang wrote: > From: Liping Zhang <liping.zhang@xxxxxxxxxxxxxx> > > Suppose that we input the following commands at first: > # nfacct add test > # iptables -A INPUT -m nfacct --nfacct-name test > > And now "test" acct's refcnt is 2, but later when we try to delete the > "test" nfacct and the related iptables rule at the same time, race maybe > happen: > CPU0 CPU1 > nfnl_acct_try_del nfnl_acct_put > atomic_dec_and_test //ref=1,testfail - > - atomic_dec_and_test //ref=0,testok > - kfree_rcu > atomic_inc //ref=1 - > > So after the rcu grace period, nf_acct will be freed but it is still linked > in the nfnl_acct_list, and we can access it later, then oops will happen. > > Convert atomic_dec_and_test and atomic_inc combinaiton to one atomic > operation atomic_cmpxchg here to fix this problem. Applied, thanks. -- 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
