From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Daniel Borkmann , John Fastabend , "David S. Miller" Subject: [PATCH 4.1 138/159] sched: cls_flow: fix panic on filter replace Date: Sat, 26 Sep 2015 13:56:24 -0700 Message-Id: <20150926205321.433415527@linuxfoundation.org> In-Reply-To: <20150926205313.363686083@linuxfoundation.org> References: <20150926205313.363686083@linuxfoundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-15 Sender: linux-kernel-owner@vger.kernel.org List-ID: 4.1-stable review patch. If anyone has any objections, please let me know. ------------------ From: Daniel Borkmann [ Upstream commit 32b2f4b196b37695fdb42b31afcbc15399d6ef91 ] The following test case causes a NULL pointer dereference in cls_flow: tc filter add dev foo parent 1: handle 0x1 flow hash keys dst action ok tc filter replace dev foo parent 1: pref 49152 handle 0x1 \ flow hash keys mark action drop To be more precise, actually two different panics are fixed, the first occurs because tcf_exts_init() is not called on the newly allocated filter when we do a replace. And the second panic uncovered after that happens since the arguments of list_replace_rcu() are swapped, the old element needs to be the first argument and the new element the second. Fixes: 70da9f0bf999 ("net: sched: cls_flow use RCU") Signed-off-by: Daniel Borkmann Acked-by: John Fastabend Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman --- net/sched/cls_flow.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) --- a/net/sched/cls_flow.c +++ b/net/sched/cls_flow.c @@ -419,6 +419,8 @@ static int flow_change(struct net *net, if (!fnew) goto err2; + tcf_exts_init(&fnew->exts, TCA_FLOW_ACT, TCA_FLOW_POLICE); + fold = (struct flow_filter *)*arg; if (fold) { err = -EINVAL; @@ -480,7 +482,6 @@ static int flow_change(struct net *net, fnew->mask = ~0U; fnew->tp = tp; get_random_bytes(&fnew->hashrnd, 4); - tcf_exts_init(&fnew->exts, TCA_FLOW_ACT, TCA_FLOW_POLICE); } fnew->perturb_timer.function = flow_perturbation; @@ -520,7 +521,7 @@ static int flow_change(struct net *net, if (*arg == 0) list_add_tail_rcu(&fnew->list, &head->filters); else - list_replace_rcu(&fnew->list, &fold->list); + list_replace_rcu(&fold->list, &fnew->list); *arg = (unsigned long)fnew;