| Message ID | e9ed6bbcf7e9d9b3fdbd3dd0b5117d9a284b4399.1437163466.git.daniel@iogearbox.net |
|---|---|
| State | Accepted, archived |
| Delegated to: | David Miller |
| Headers | show |
On 15-07-17 01:38 PM, Daniel Borkmann wrote: > 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 <daniel@iogearbox.net> > --- > net/sched/cls_flow.c | 5 +++-- > 1 file changed, 3 insertions(+), 2 deletions(-) > Thanks again, I must have missed running replace tests in these cases. Acked-by: John Fastabend <john.r.fastabend@intel.com> -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/net/sched/cls_flow.c b/net/sched/cls_flow.c index 76bc3a2..bb2a0f5 100644 --- a/net/sched/cls_flow.c +++ b/net/sched/cls_flow.c @@ -425,6 +425,8 @@ static int flow_change(struct net *net, struct sk_buff *in_skb, if (!fnew) goto err2; + tcf_exts_init(&fnew->exts, TCA_FLOW_ACT, TCA_FLOW_POLICE); + fold = (struct flow_filter *)*arg; if (fold) { err = -EINVAL; @@ -486,7 +488,6 @@ static int flow_change(struct net *net, struct sk_buff *in_skb, 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; @@ -526,7 +527,7 @@ static int flow_change(struct net *net, struct sk_buff *in_skb, 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;
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 <daniel@iogearbox.net> --- net/sched/cls_flow.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-)