Merge branch 'add_assertion_to_pci_driver' into 'master'

Add Non-Null Check to common driver library to prevent a kernel crash due to an unitialized PCI BAR

See merge request redox-os/drivers!200

common/src/lib.rs

@@ -126,6 +126,12 @@ pub unsafe fn physmap(
     ty: MemoryType,
 ) -> Result<*mut ()> {
     // TODO: arraystring?
+
+    //Return an error rather than potentially crash the kernel.
+    if(base_phys == 0) {
+        return Err(Error::new(EINVAL));
+    }
+
     let path = format!(
         "/scheme/memory/physical@{}",
         match ty {

pcid/src/driver_interface/mod.rs

@@ -373,6 +373,7 @@ impl PciFunctionHandle {
             Ok(mapped_bar)
         } else {
             let (bar, bar_size) = self.config.func.bars[bir as usize].expect_mem();
+
             let ptr = unsafe {
                 common::physmap(
                     bar,