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

4 messages, 3 authors, 2007-07-25 · open the first message on its own page

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

From: Adrian Bunk <hidden>
Date: 2007-07-23 01:21:01

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  -->


cu
Adrian

-- 

       "Is there not promise of rain?" Ling Tan asked suddenly out
        of the darkness. There had been need of rain for many days.
       "Only a promise," Lao Er said.
                                       Pearl S. Buck - Dragon Seed

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

From: Eric Van Hensbergen <hidden>
Date: 2007-07-25 18:43:31

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

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

From: "Latchesar Ionkov" <lucho@ionkov.net>
Date: 2007-07-25 19:13:51

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

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

From: Eric Van Hensbergen <hidden>
Date: 2007-07-25 19:45:50

On 7/25/07, Latchesar Ionkov [off-list ref] wrote:
Yep, it's a leak.
Okay, I'll roll that into the patch as well.

           -eric
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