Re: ipv6: handle -EFAULT from skb_copy_bits

On Tue, Dec 20, 2016 at 2:12 PM, Dave Jones [off-list ref] wrote:

        fd = socket(AF_INET6, SOCK_RAW, 7);

        setsockopt(fd, SOL_IPV6, IPV6_CHECKSUM, &zero, 4);
        setsockopt(fd, SOL_IPV6, IPV6_DSTOPTS, &buf, LEN);

Interesting, you set the checksum offset to be 0, but the packet size
is actually 49, transport header is located at offset 48, so apparently
the packet doesn't have room for a 16bit checksum after network header.

Your original patch seems reasonable to me, unless there is some
check in __ip6_append_data() which is supposed to catch this, but
CHECKSUM is specific to raw socket only.