Re: Kernel memory corruption in CIPSO labeled TCP packets processing.

On Tue, Jan 29, 2019 at 2:23 AM Nazarov Sergey [off-list ref] wrote:

29.01.2019, 01:18, "Paul Moore" [off-list ref]:

quoted

If we don't pass a skb into ip_options_compile(), meaning both "skb"
and "rt" will be NULL, then I don't believe the option data will
change. Am I missing something?

I mean, in cipso_v4_error we copy option data from skb before ip_options_compile call:
+       memcpy(opt->__data, (unsigned char *)&(ip_hdr(skb)[1]), opt->optlen);
But skb IP header data could be already changed by first call of ip_options_compile
when packet received.

There are several cases where the stack ends up calling icmp_send()
after the skb has been through ip_options_compile(), that should be
okay.

-- 
paul moore
www.paul-moore.com