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librdmacm: prevent NULL pointer access during device initialization #1547

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Feb 4, 2025
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librdmacm: prevent NULL pointer access during device initialization #1547

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21 changes: 17 additions & 4 deletions librdmacm/cma.c
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Original file line number Diff line number Diff line change
Expand Up @@ -2252,17 +2252,30 @@ int rdma_ack_cm_event(struct rdma_cm_event *event)

static void ucma_process_addr_resolved(struct cma_event *evt)
{
struct rdma_cm_id *id = &evt->id_priv->id;

if (af_ib_support) {
evt->event.status = ucma_query_addr(&evt->id_priv->id);
evt->event.status = ucma_query_addr(id);
if (!evt->event.status && !id->verbs)
goto err_dev;

if (!evt->event.status &&
evt->id_priv->id.verbs->device->transport_type == IBV_TRANSPORT_IB)
evt->event.status = ucma_query_gid(&evt->id_priv->id);
id->verbs->device->transport_type == IBV_TRANSPORT_IB) {
evt->event.status = ucma_query_gid(id);
}
} else {
evt->event.status = ucma_query_route(&evt->id_priv->id);
evt->event.status = ucma_query_route(id);
if (!evt->event.status && !id->verbs)
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In that flow, the 'id->verbs' is not used compared to the above 'af_ib_support' case.

Do we really need to fail the call once id->verbs wasn't set ? no NULL pointer issue is expected here.

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I think we still need to fail the call in af_ib_support == 0 case, as the man page says

If successful, the specified rdma_cm_id will be bound to a local device.

However, in the current implementation, no device binding occurs in this case.

This becomes problematic in the typical RDMA CM connection setup flow where rdma_resolve_route is called after receiving RDMA_CM_EVENT_ADDR_RESOLVED. The following code in rdma_resolve_route would trigger a NULL pointer dereference:

int rdma_resolve_route(struct rdma_cm_id *id, int timeout_ms)
{
        ... snip ...
        // id->verbs is NULL here
        if (id->verbs->device->transport_type == IBV_TRANSPORT_IB) {
                ret = ucma_set_ib_route(id);
                if (!ret)
                        goto out;
        }
      
        ... snip ...
}

So we'd better set the event to RDMA_CM_EVENT_ADDR_ERROR and let user handle the error event

goto err_dev;
}

if (evt->event.status)
evt->event.event = RDMA_CM_EVENT_ADDR_ERROR;
return;

err_dev:
evt->event.status = ERR(ENODEV);
evt->event.event = RDMA_CM_EVENT_ADDR_ERROR;
}

static void ucma_process_route_resolved(struct cma_event *evt)
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