diff mbox

[net] net: __skb_flow_dissect() must cap its return value

Message ID 1478736286.16809.17.camel@edumazet-glaptop3.roam.corp.google.com
State Accepted, archived
Delegated to: David Miller
Headers show

Commit Message

Eric Dumazet Nov. 10, 2016, 12:04 a.m. UTC 
From: Eric Dumazet <edumazet@google.com>

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 <edumazet@google.com>
Reported-by: Yibin Yang <yibyang@cisco.com
Acked-by: Alexander Duyck <alexander.h.duyck@intel.com>
Acked-by: Willem de Bruijn <willemb@google.com>
Acked-by: Alexei Starovoitov <ast@kernel.org>
---
 net/core/flow_dissector.c |   11 ++++++++---
 1 file changed, 8 insertions(+), 3 deletions(-)

Comments

David Miller Nov. 13, 2016, 4:42 a.m. UTC | #1 
From: Eric Dumazet <eric.dumazet@gmail.com>
Date: Wed, 09 Nov 2016 16:04:46 -0800

> From: Eric Dumazet <edumazet@google.com>
> 
> 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 <edumazet@google.com>
> Reported-by: Yibin Yang <yibyang@cisco.com
> Acked-by: Alexander Duyck <alexander.h.duyck@intel.com>
> Acked-by: Willem de Bruijn <willemb@google.com>
> Acked-by: Alexei Starovoitov <ast@kernel.org>

Applied and queued up for -stable, thanks Eric.
diff mbox

Patch

diff --git a/net/core/flow_dissector.c b/net/core/flow_dissector.c
index 44e6ba9d3a6b..5a908c534bec 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 @@  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);