Re: net/9p/mux.c: use-after-free

Yep, it's a leak.

Thanks,
    Lucho

On 7/25/07, Eric Van Hensbergen [off-list ref] wrote:

On 7/22/07, Adrian Bunk [off-list ref] wrote:

quoted

The Coverity checker spotted the following use-after-free
in net/9p/mux.c:

<--  snip  -->

...
struct p9_conn *p9_conn_create(struct p9_transport *trans, int msize,
                                    unsigned char *extended)
{
...
        if (!m->tagpool) {
                kfree(m);
                return ERR_PTR(PTR_ERR(m->tagpool));
        }
...

<--  snip  -->

I've got a fix for this one:
        if (!m->tagpool) {
                mtmp = ERR_PTR(PTR_ERR(m->tagpool));
                kfree(m);
                return mtmp;
        }

but I was wondering about one of the other returns further down the function:

...
        memset(&m->poll_waddr, 0, sizeof(m->poll_waddr));
        m->poll_task = NULL;
        n = p9_mux_poll_start(m);
        if (n)
                return ERR_PTR(n);

        n = trans->poll(trans, &m->pt);
...

lucho: doesn't that constitute a leak?  Shouldn't we be doing:

        if (n) {
                kfree(m);
                return ERR_PTR(n);
        }

         -eric