[3.11.y.z extended stable] Patch "netfilter: nf_conntrack_dccp: fix skb_header_pointer API usages" has been added to staging queue

[Luis Henriques]

This is a note to let you know that I have just added a patch titled

    netfilter: nf_conntrack_dccp: fix skb_header_pointer API usages

to the linux-3.11.y-queue branch of the 3.11.y.z extended stable tree 
which can be found at:

 http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.11.y-queue

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.11.y.z tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Luis

------

>From 0fc3386f220a27db68f9fbf0ca21a99d5d8b7d1d Mon Sep 17 00:00:00 2001
From: Daniel Borkmann <dborkman at redhat.com>
Date: Mon, 6 Jan 2014 00:57:54 +0100
Subject: netfilter: nf_conntrack_dccp: fix skb_header_pointer API usages

commit b22f5126a24b3b2f15448c3f2a254fc10cbc2b92 upstream.

Some occurences in the netfilter tree use skb_header_pointer() in
the following way ...

  struct dccp_hdr _dh, *dh;
  ...
  skb_header_pointer(skb, dataoff, sizeof(_dh), &dh);

... where dh itself is a pointer that is being passed as the copy
buffer. Instead, we need to use &_dh as the forth argument so that
we're copying the data into an actual buffer that sits on the stack.

Currently, we probably could overwrite memory on the stack (e.g.
with a possibly mal-formed DCCP packet), but unintentionally, as
we only want the buffer to be placed into _dh variable.

Fixes: 2bc780499aa3 ("[NETFILTER]: nf_conntrack: add DCCP protocol support")
Signed-off-by: Daniel Borkmann <dborkman at redhat.com>
Signed-off-by: Pablo Neira Ayuso <pablo at netfilter.org>
Signed-off-by: Luis Henriques <luis.henriques at canonical.com>
---
 net/netfilter/nf_conntrack_proto_dccp.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/net/netfilter/nf_conntrack_proto_dccp.c b/net/netfilter/nf_conntrack_proto_dccp.c
index a99b6c3..59359be 100644
--- a/net/netfilter/nf_conntrack_proto_dccp.c
+++ b/net/netfilter/nf_conntrack_proto_dccp.c
@@ -428,7 +428,7 @@ static bool dccp_new(struct nf_conn *ct, const struct sk_buff *skb,
 	const char *msg;
 	u_int8_t state;

-	dh = skb_header_pointer(skb, dataoff, sizeof(_dh), &dh);
+	dh = skb_header_pointer(skb, dataoff, sizeof(_dh), &_dh);
 	BUG_ON(dh == NULL);

 	state = dccp_state_table[CT_DCCP_ROLE_CLIENT][dh->dccph_type][CT_DCCP_NONE];
@@ -486,7 +486,7 @@ static int dccp_packet(struct nf_conn *ct, const struct sk_buff *skb,
 	u_int8_t type, old_state, new_state;
 	enum ct_dccp_roles role;

-	dh = skb_header_pointer(skb, dataoff, sizeof(_dh), &dh);
+	dh = skb_header_pointer(skb, dataoff, sizeof(_dh), &_dh);
 	BUG_ON(dh == NULL);
 	type = dh->dccph_type;

@@ -577,7 +577,7 @@ static int dccp_error(struct net *net, struct nf_conn *tmpl,
 	unsigned int cscov;
 	const char *msg;

-	dh = skb_header_pointer(skb, dataoff, sizeof(_dh), &dh);
+	dh = skb_header_pointer(skb, dataoff, sizeof(_dh), &_dh);
 	if (dh == NULL) {
 		msg = "nf_ct_dccp: short packet ";
 		goto out_invalid;
--
1.9.1