i40iw: Add missing NULL check for MPA private data

Add NULL check for pdata and pdata->addr before the memcpy in
i40iw_form_cm_frame(). This fixes a NULL pointer de-reference
which occurs when the MPA private data pointer is NULL. Also
only copy pdata->size bytes in the memcpy to prevent reading
past the length of the private data buffer provided by upper layer.

Fixes: f27b4746 ("i40iw: add connection management code")
Reported-by: Stefan Assmann <sassmann@redhat.com>
Signed-off-by: Mustafa Ismail <mustafa.ismail@intel.com>
Signed-off-by: Shiraz Saleem <shiraz.saleem@intel.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>

drivers/infiniband/hw/i40iw/i40iw_cm.c

@@ -535,8 +535,8 @@ static struct i40iw_puda_buf *i40iw_form_cm_frame(struct i40iw_cm_node *cm_node,
 		buf += hdr_len;
 	}
 
-	if (pd_len)
-		memcpy(buf, pdata->addr, pd_len);
+	if (pdata && pdata->addr)
+		memcpy(buf, pdata->addr, pdata->size);
 
 	atomic_set(&sqbuf->refcount, 1);