From 34fad54c2537f7c99d07375e50cb30aa3c23bd83 Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Wed, 9 Nov 2016 16:04:46 -0800 Subject: [PATCH] net: __skb_flow_dissect() must cap its return value After Tom patch, thoff field could point past the end of the buffer, this could fool some callers. If an skb was provided, skb->len should be the upper limit. If not, hlen is supposed to be the upper limit. Fixes: a6e544b0a88b ("flow_dissector: Jump to exit code in __skb_flow_dissect") Signed-off-by: Eric Dumazet Reported-by: Yibin Yang Acked-by: Willem de Bruijn Acked-by: Alexei Starovoitov Signed-off-by: David S. Miller --- net/core/flow_dissector.c | 11 ++++++++--- 1 file changed, 8 insertions(+), 3 deletions(-) diff --git a/net/core/flow_dissector.c b/net/core/flow_dissector.c index ab193e5def07..69e4463a4b1b 100644 --- a/net/core/flow_dissector.c +++ b/net/core/flow_dissector.c @@ -122,7 +122,7 @@ bool __skb_flow_dissect(const struct sk_buff *skb, struct flow_dissector_key_keyid *key_keyid; bool skip_vlan = false; u8 ip_proto = 0; - bool ret = false; + bool ret; if (!data) { data = skb->data; @@ -549,12 +549,17 @@ ip_proto_again: out_good: ret = true; -out_bad: + key_control->thoff = (u16)nhoff; +out: key_basic->n_proto = proto; key_basic->ip_proto = ip_proto; - key_control->thoff = (u16)nhoff; return ret; + +out_bad: + ret = false; + key_control->thoff = min_t(u16, nhoff, skb ? skb->len : hlen); + goto out; } EXPORT_SYMBOL(__skb_flow_dissect); -- 2.20.1