On Wed, Jan 03, 2018 at 10:53:14PM -0800, Eric Dumazet wrote: > On Wed, 2018-01-03 at 21:13 -0800, Eric Dumazet wrote: > > Note: all commands must start from beginning of the line in the email body. > > > > I guess skb_probe_transport_header() should be hardened to reject malicious > > packets given by user space, instead of being gentle. > > Although bug triggered for this particular repro is in flow dissector > :/ > > I will test : > > diff --git a/net/core/flow_dissector.c b/net/core/flow_dissector.c > index > 15ce300637650e17fcab7e378b20fe7972686d46..544bddf08e13c7f6e47aadc737244c9ba5af56b2 > 100644 > --- a/net/core/flow_dissector.c > +++ b/net/core/flow_dissector.c > @@ -976,8 +976,8 @@ bool __skb_flow_dissect(const struct sk_buff *skb, > out_good: > ret = true; > > - key_control->thoff = (u16)nhoff; > out: > + key_control->thoff = min_t(u16, nhoff, skb ? skb->len : hlen); > key_basic->n_proto = proto; > key_basic->ip_proto = ip_proto; > > @@ -985,7 +985,6 @@ bool __skb_flow_dissect(const struct sk_buff *skb, > > out_bad: > ret = false; > - key_control->thoff = min_t(u16, nhoff, skb ? skb->len : hlen); > goto out; > } > EXPORT_SYMBOL(__skb_flow_dissect);
Fix for this was commit d0c081b49137cd: #syz fix: flow_dissector: properly cap thoff field But a crash with the same signature is still occurring, so it should eventually get reported again. C reproducer is here, it works on Linus' tree (commit 036db8bd963): https://syzkaller.appspot.com/text?tag=ReproC&x=105b1ae7800000 - Eric
