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Commit 34fad54c authored by Eric Dumazet's avatar Eric Dumazet Committed by David S. Miller
Browse files

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: a6e544b0 ("flow_dissector: Jump to exit code in __skb_flow_dissect")
Signed-off-by: default avatarEric Dumazet <edumazet@google.com>
Reported-by: default avatarYibin Yang <yibyang@cisco.com>
Acked-by: default avatarAlexander Duyck <alexander.h.duyck@intel.com>
Acked-by: default avatarWillem de Bruijn <willemb@google.com>
Acked-by: default avatarAlexei Starovoitov <ast@kernel.org>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 79774d6b

net/core/flow_dissector.c

+8 −3
Original line number Diff line number Diff line
@@ -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 @@ bool __skb_flow_dissect(const struct sk_buff *skb, 
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);