Re: [PATCH] unix domain sockets bugfix

From: Balazs Scheidler (bazsi@balabit.hu)
Date: Mon Oct 07 2002 - 03:01:01 EST

On Mon, Oct 07, 2002 at 12:48:00AM -0700, David S. Miller wrote:
> From: Balazs Scheidler <bazsi@balabit.hu>
> Date: Mon, 7 Oct 2002 09:35:32 +0200
>
> The returned socklen is 2, but the sockaddr.family is not touched. A fix is
> below:
>
> Since msg->msg_namelen is zero, msg->msg_name should not be
> interpreted in any way at all.

You would be right, if it would be zero, but it isn't:

373 res = recvfrom(closure->fd, buffer, length, 0, (struct sockaddr *) addr, (socklen_t *) addrlen);
(gdb) n
375 if (*addrlen == 2) {
(gdb) p *addrlen
$2 = 2

Checking out the code again:

static void unix_copy_addr(struct msghdr *msg, struct sock *sk)
{
        msg->msg_namelen = sizeof(short);
        if (sk->protinfo.af_unix.addr) {
                msg->msg_namelen=sk->protinfo.af_unix.addr->len;
                memcpy(msg->msg_name,
                       sk->protinfo.af_unix.addr->name,
                       sk->protinfo.af_unix.addr->len);
        }
}

namelen is explicitly set to sizeof(short) == 2.

This is 2.4.18 

-- 
Bazsi
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