netdev - Re: [PATCH net] ipv4: fix memory leaks in ip_cmsg

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Date:	Mon, 15 Feb 2016 12:11:34 -0800
From:	Cong Wang <xiyou.wangcong@...il.com>
To:	Eric Dumazet <eric.dumazet@...il.com>
Cc:	Dmitry Vyukov <dvyukov@...gle.com>,
	David Miller <davem@...emloft.net>,
	netdev <netdev@...r.kernel.org>
Subject: Re: [PATCH net] ipv4: fix memory leaks in ip_cmsg_send() callers

On Thu, Feb 4, 2016 at 6:23 AM, Eric Dumazet <eric.dumazet@...il.com> wrote:
> From: Eric Dumazet <edumazet@...gle.com>
>
> Dmitry reported memory leaks of IP options allocated in
> ip_cmsg_send() when/if this function returns an error.
>
> Callers are responsible for the freeing.

Right, because there is a loop in ip_cmsg_send(), so the callers
are easier to free it than the callee.

The other thing is we perhaps have another leak in the following code:

        if (ipc.opt && ipc.opt->opt.srr) {
                if (!daddr)
                        return -EINVAL;
                faddr = ipc.opt->opt.faddr;
        }

since ipc.opt could be allocated on heap... We need something like:

@@ -770,8 +770,11 @@ static int ping_v4_sendmsg(struct sock *sk,
struct msghdr *msg, size_t len)
        ipc.addr = faddr = daddr;

        if (ipc.opt && ipc.opt->opt.srr) {
-               if (!daddr)
+               if (!daddr) {
+                       if (free)
+                               kfree(ipc.opt);
                        return -EINVAL;
+               }
                faddr = ipc.opt->opt.faddr;
        }
        tos = get_rttos(&ipc, inet);