Subject: re: gre: Support GRE over IPv6

From: Dan Carpenter <[email-masked]>
Date: Thu, 13 Sep 2012 19:01:05 +0300

Hello Dmitry Kozlov,

The patch c12b395a4664: "gre: Support GRE over IPv6" from Aug 10, 
2012, leads to the following warning:
net/ipv6/ip6_gre.c:1299 ip6gre_header_parse()
	 error: memcpy() 'haddr' too small (8 vs 16)

net/ipv6/ip6_gre.c
  1296  static int ip6gre_header_parse(const struct sk_buff *skb, unsigned char *haddr)
  1297  {
  1298          const struct ipv6hdr *ipv6h = (const struct ipv6hdr *)skb_mac_header(skb);
  1299          memcpy(haddr, &ipv6h->saddr, sizeof(struct in6_addr));
                       ^^^^^
Smatch thinks this buffer is only 8 characters sometimes.

  1300          return sizeof(struct in6_addr);
  1301  }

One call tree where this would happen would be the
(struct sockaddr_ll *)sll->sll_addr[] in packet_rcv().

-> packet_rcv()
   -> dev_parse_header()
      -> ip6gre_header_parse()

I don't know the code well enough to say if this is a bug or not.  Could
you take a look?

regards,
dan carpenter