[PATCH v2 edk2-platforms 3/3] Platform/ARM/BdsLib: maintain alignment for DevicePaths

[Ard Biesheuvel <ard.biesheuvel@linaro.org>]

DevicePath node types may have any size, and so it is up to the
code that manipulates them to ensure that dereferencing them only
occurs when the pointer is aligned explicitly.

Since BdsConnectAndUpdateDevicePath() has only two callers, one of
which itself, we can simply duplicate the device path (similar to
how DxeCore's CoreConnectController () does it), and free the pool
allocation again on the way out. (Note that the allocation only
occurs when the non-recursive path is taken and the function
returns EFI_SUCCESS)

Contributed-under: TianoCore Contribution Agreement 1.1
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
---
 Platform/ARM/Library/BdsLib/BdsFilePath.c | 12 ++++++++----
 1 file changed, 8 insertions(+), 4 deletions(-)

diff --git a/Platform/ARM/Library/BdsLib/BdsFilePath.c b/Platform/ARM/Library/BdsLib/BdsFilePath.c
index 62f796e5526d..ad66b2f82718 100644
--- a/Platform/ARM/Library/BdsLib/BdsFilePath.c
+++ b/Platform/ARM/Library/BdsLib/BdsFilePath.c
@@ -423,8 +423,8 @@ BdsConnectAndUpdateDevicePath (
     }
   }
 
-  if (RemainingDevicePath) {
-    *RemainingDevicePath = Remaining;
+  if (!EFI_ERROR (Status) && RemainingDevicePath != NULL) {
+    *RemainingDevicePath = DuplicateDevicePath (Remaining);
   }
 
   return Status;
@@ -1314,14 +1314,18 @@ BdsLoadImageAndUpdateDevicePath (
   }
 
   FileLoader = FileLoaders;
+  Status = EFI_UNSUPPORTED;
   while (FileLoader->Support != NULL) {
     if (FileLoader->Support (*DevicePath, Handle, RemainingDevicePath)) {
-      return FileLoader->LoadImage (DevicePath, Handle, RemainingDevicePath, Type, Image, FileSize);
+      Status = FileLoader->LoadImage (DevicePath, Handle, RemainingDevicePath,
+                             Type, Image, FileSize);
+      break;
     }
     FileLoader++;
   }
 
-  return EFI_UNSUPPORTED;
+  FreePool (RemainingDevicePath);
+  return Status;
 }
 
 EFI_STATUS
-- 
2.17.1