MdeModulePkg/PartitionDxe: Fix media probe

The call in ProbeMediaStatus() to the ReadDisk() function of the
EFI_DISK_IO_PROTOCOL interface implemented in DiskIoDxe/DiskIo.c
crashed in DiskIo2ReadWriteDisk() because of the NULL value of
the destination buffer pointer.

Pass the address of a buffer in the stack instead of a NULL
pointer.

In addition to avoiding the crash, that way, the media probe does not
depend anymore on the way the EFI_DISK_IO_PROTOCOL implementation deals
with a NULL value of the destination buffer pointer as the UEFI
specification does not specify the expected behaviour.

Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Ronald Cron <Ronald.Cron@arm.com>
Reviewed-by: Olivier Martin <olivier.martin@arm.com>
Reviewed-by: Ruiyu Ni <ruiyu.ni@intel.com>



git-svn-id: https://svn.code.sf.net/p/edk2/code/trunk/edk2@17859 6f19259b-4bc3-4df7-8a09-765794883524

MdeModulePkg/Universal/Disk/PartitionDxe/Partition.c

@@ -576,11 +576,15 @@ ProbeMediaStatus (
   )
 {
   EFI_STATUS                 Status;
+  UINT8                      Buffer[1];
 
   //
-  // Read 1 byte from offset 0 but passing NULL as buffer pointer
+  // Read 1 byte from offset 0 to check if the MediaId is still valid.
+  // The reading operation is synchronious thus it is not worth it to
+  // allocate a buffer from the pool. The destination buffer for the
+  // data is in the stack.
   //
-  Status = DiskIo->ReadDisk (DiskIo, MediaId, 0, 1, NULL);
+  Status = DiskIo->ReadDisk (DiskIo, MediaId, 0, 1, (VOID*)Buffer);
   if ((Status == EFI_NO_MEDIA) || (Status == EFI_MEDIA_CHANGED)) {
     return Status;
   }