Re: [PATCH net-next 1/2] ipv6: remove unnecessary codes in tcp_ipv6.c

From: RongQing Li <redacted>
Date: Mon, 2 Jul 2012 13:23:09 +0800

2012/7/2 David Miller [off-list ref]:

quoted

From: roy.qing.li@gmail.com
Date: Mon,  2 Jul 2012 11:18:59 +0800

quoted

-     if (opt) {
-             newnp->opt = ipv6_dup_options(newsk, opt);
-             if (opt != np->opt)
-                     sock_kfree_s(sk, opt, opt->tot_len);

This is bogus, if we copy the options into a new copy in
ipv6_dup_options() we have to free the old one or else we
leak it.

Do you mean I should free newnp->opt firstly ?

If I understand it right, I think we do not need to free it. the
process is below:

newsk = tcp_v4_syn_recv_sock(sk, skb, req, dst);
..
newnp = inet6_sk(newsk);
..
memcpy(newnp, np, sizeof(struct ipv6_pinfo));
..
newnp->opt         = NULL;

So newnp->opt is not a effective memory.

ipv6_dup_options() allocates new memory for the options and this call
statement assigns that new pointer to np->opt.

If you do not free the old (before ipv6_dup_options()) np->opt memory
here, it is lost forever.