Patch "net: __skb_flow_dissect() must cap its return value" has been added to the 4.8-stable tree

Patch "net: __skb_flow_dissect() must cap its return value" has been added to the 4.8-stable tree

[gregkh]

This is a note to let you know that I've just added the patch titled

    net: __skb_flow_dissect() must cap its return value

to the 4.8-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     net-__skb_flow_dissect-must-cap-its-return-value.patch
and it can be found in the queue-4.8 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From foo@baz Fri Nov 18 11:35:46 CET 2016
From: Eric Dumazet <edumazet@google.com>
Date: Wed, 9 Nov 2016 16:04:46 -0800
Subject: net: __skb_flow_dissect() must cap its return value

From: Eric Dumazet <edumazet@google.com>


[ Upstream commit 34fad54c2537f7c99d07375e50cb30aa3c23bd83 ]

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>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 net/core/flow_dissector.c |   11 ++++++++---
 1 file changed, 8 insertions(+), 3 deletions(-)

--- a/net/core/flow_dissector.c
+++ b/net/core/flow_dissector.c
@@ -118,7 +118,7 @@ bool __skb_flow_dissect(const struct sk_
 	struct flow_dissector_key_tags *key_tags;
 	struct flow_dissector_key_keyid *key_keyid;
 	u8 ip_proto = 0;
-	bool ret = false;
+	bool ret;
 
 	if (!data) {
 		data = skb->data;
@@ -481,12 +481,17 @@ 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);
 


Patches currently in stable-queue which might be from edumazet@google.com are

queue-4.8/net-__skb_flow_dissect-must-cap-its-return-value.patch
queue-4.8/tcp-take-care-of-truncations-done-by-sk_filter.patch
queue-4.8/net-clear-sk_err_soft-in-sk_clone_lock.patch
queue-4.8/dccp-do-not-release-listeners-too-soon.patch
queue-4.8/net-mangle-zero-checksum-in-skb_checksum_help.patch
queue-4.8/tcp-fix-return-value-for-partial-writes.patch
queue-4.8/ipv6-dccp-fix-out-of-bound-access-in-dccp_v6_err.patch
queue-4.8/ipv6-dccp-add-missing-bind_conflict-to-dccp_ipv6_mapped.patch
queue-4.8/tcp-fix-potential-memory-corruption.patch
queue-4.8/dccp-do-not-send-reset-to-already-closed-sockets.patch
queue-4.8/dccp-fix-out-of-bound-access-in-dccp_v4_err.patch
queue-4.8/sock-fix-sendmmsg-for-partial-sendmsg.patch