[PATCH 4.4 028/137] net: vrf: Remove direct access to skb->data

[Greg Kroah-Hartman]

4.4-stable review patch.  If anyone has any objections, please let me know.

------------------

From: David Ahern <dsa@xxxxxxxxxxxxxxxxxxx>

[ Upstream commit 65c38aa653c14df49e19faad74bd375f36e61c57 ]

Nik pointed that the VRF driver should be using skb_header_pointer
instead of accessing skb->data and bits beyond directly which can
be garbage.

Fixes: 35402e313663 ("net: Add IPv6 support to VRF device")
Cc: Nikolay Aleksandrov <nikolay@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: David Ahern <dsa@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: Nikolay Aleksandrov <nikolay@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
 drivers/net/vrf.c |   13 ++++++++-----
 1 file changed, 8 insertions(+), 5 deletions(-)

--- a/drivers/net/vrf.c
+++ b/drivers/net/vrf.c
@@ -114,20 +114,23 @@ static struct dst_ops vrf_dst_ops = {
 #if IS_ENABLED(CONFIG_IPV6)
 static bool check_ipv6_frame(const struct sk_buff *skb)
 {
-	const struct ipv6hdr *ipv6h = (struct ipv6hdr *)skb->data;
-	size_t hlen = sizeof(*ipv6h);
+	const struct ipv6hdr *ipv6h;
+	struct ipv6hdr _ipv6h;
 	bool rc = true;
 
-	if (skb->len < hlen)
+	ipv6h = skb_header_pointer(skb, 0, sizeof(_ipv6h), &_ipv6h);
+	if (!ipv6h)
 		goto out;
 
 	if (ipv6h->nexthdr == NEXTHDR_ICMP) {
 		const struct icmp6hdr *icmph;
+		struct icmp6hdr _icmph;
 
-		if (skb->len < hlen + sizeof(*icmph))
+		icmph = skb_header_pointer(skb, sizeof(_ipv6h),
+					   sizeof(_icmph), &_icmph);
+		if (!icmph)
 			goto out;
 
-		icmph = (struct icmp6hdr *)(skb->data + sizeof(*ipv6h));
 		switch (icmph->icmp6_type) {
 		case NDISC_ROUTER_SOLICITATION:
 		case NDISC_ROUTER_ADVERTISEMENT: