On 03/23/2017 04:44 AM, Cedric Bosdonnat wrote:
> On Wed, 2017-03-22 at 07:16 -0400, John Ferlan wrote:
>> [...]
>>
>>> +
>>> +static int
>>> +virNetDevIPCheckIPv6ForwardingCallback(const struct nlmsghdr *resp,
>>> + void *opaque)
>>> +{
>>> + struct rtmsg *rtmsg = NLMSG_DATA(resp);
>>> + int accept_ra = -1;
>>> + struct rtattr *rta;
>>> + char *ifname = NULL;
>>> + struct virNetDevIPCheckIPv6ForwardingData *data = opaque;
>>> + int ret = 0;
>>> + int len = RTM_PAYLOAD(resp);
>>> + int oif = -1;
>>> +
>>> + /* Ignore messages other than route ones */
>>> + if (resp->nlmsg_type != RTM_NEWROUTE)
>>> + return ret;
>>> +
>>> + /* Extract a few attributes */
>>> + for (rta = RTM_RTA(rtmsg); RTA_OK(rta, len); rta = RTA_NEXT(rta, len)) {
>>> + switch (rta->rta_type) {
>>> + case RTA_OIF:
>>> + oif = *(int *)RTA_DATA(rta);
>>> +
>>> + if (!(ifname = virNetDevGetName(oif)))
>>> + goto error;
>>> + break;
>>
>> Did you really mean to break from the for loop if ifname is set? This
>> breaks only from the switch/case. Of course Coverity doesn't know much
>> more than you'd be going back to the top of the for loop and could
>> overwrite ifname again. It proclaims a resource leak...
>
> In my dev version I was also getting the RTA_DST attribute to print some
> debugging message that I removed in the submitted version. The break was
> here between the switch cases.
>
> In the current case I don't really care if we break out of the loop or not.
> As there aren't that many attributes in an rtnetlink message to loop over,
> breaking wouldn't gain a lot of cycles.
>
> What I don't get though is what this break is actually doing? isn't it
> for the switch case even though there is no other case after it?
>
> --
> Cedric
So should this be changed to:
if (rta->rta_type == RTA_OIF) {
oif = *(int *)RTA_DATA(rta);
if (!(ifname = virNetDevGetName(oif)))
goto error;
break;
}
leaving two questions in my mind
1. Can there be more than one RTA_OIF
2. If we don't finish the loop (e.g. we break out), then does one of
the subsequent checks fail?
Is it more of a problem that we find *two* RTA_OIF's and thus should add a:
if (ifname) {
VIR_DEBUG("some sort of message");
goto error;
}
prior to the virNetDevGetName call and then remove the break;?
John (who doesn't know the answer!)
BTW: The issue from patch4 is resolved by my 22 patch bomb from yesterday
>
>> John
>>> + }
>>> + }
>>> +
>>> + /* No need to do anything else for non RA routes */
>>> + if (rtmsg->rtm_protocol != RTPROT_RA)
>>> + goto cleanup;
>>> +
>>> + data->hasRARoutes = true;
>>> +
>>> + /* Check the accept_ra value for the interface */
>>> + accept_ra = virNetDevIPGetAcceptRA(ifname);
>>> + VIR_DEBUG("Checking route for device %s, accept_ra: %d", ifname, accept_ra);
>>> +
>>> + if (accept_ra != 2 && VIR_APPEND_ELEMENT(data->devices, data->ndevices, ifname) < 0)
>>> + goto error;
>>> +
>>> + cleanup:
>>> + VIR_FREE(ifname);
>>> + return ret;
>>> +
>>> + error:
>>> + ret = -1;
>>> + goto cleanup;
>>> +}
>>
>>
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