net: vrf: Remove direct access to skb->data

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@cumulusnetworks.com>
Signed-off-by: David Ahern <dsa@cumulusnetworks.com>
Signed-off-by: Nikolay Aleksandrov <nikolay@cumulusnetworks.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/drivers/net/vrf.c b/drivers/net/vrf.c
index 66addb7..bdcf617 100644 (file)
--- a/drivers/net/vrf.c
+++ b/drivers/net/vrf.c
@@ -104,20 +104,23 @@ 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: