Re: [Patch] ShellPkg/Hexedit: Fix FreePool() ASSERT() when writing disk

["Ni, Ruiyu" <ruiyu.ni@intel.com>]

I agree to use the same style of code as what the other functions do.

Reviewed-by: Ruiyu Ni <ruiyu.ni@intel.com>
>-----Original Message-----
>From: Kinney, Michael D
>Sent: Thursday, September 29, 2016 8:38 AM
>To: edk2-devel@lists.01.org
>Cc: Carsey, Jaben <jaben.carsey@intel.com>; Ni, Ruiyu <ruiyu.ni@intel.com>
>Subject: [Patch] ShellPkg/Hexedit: Fix FreePool() ASSERT() when writing disk
>
>The HDiskImageSave() function copies a device path using
>DuplicateDevicePath() and passes that device path to
>gBS->LocateDevicePath() that changes the value of the
>device path pointer.  When FreePool() is called with the
>modified device path pointer, the FreePool() service
>generates an ASSERT() because the signature for the pool
>head can not be found.
>
>The function HDiskImageRead() immediately above
>HDiskImageSave() has the correct algorithm that uses an
>additional local variable called DupDevicePathForFree to
>preserve the pointer to the allocated buffer so it can
>be used in the call to FreePool().
>
>Bug: <https://bugzilla.tianocore.org/show_bug.cgi?id=131>
>
>Cc: Jaben Carsey <jaben.carsey@intel.com>
>Cc: Ruiyu Ni <ruiyu.ni@intel.com>
>Contributed-under: TianoCore Contribution Agreement 1.0
>Signed-off-by: Michael Kinney <michael.d.kinney@intel.com>
>---
> ShellPkg/Library/UefiShellDebug1CommandsLib/HexEdit/DiskImage.c | 4 +++-
> 1 file changed, 3 insertions(+), 1 deletion(-)
>
>diff --git a/ShellPkg/Library/UefiShellDebug1CommandsLib/HexEdit/DiskImage.c
>b/ShellPkg/Library/UefiShellDebug1CommandsLib/HexEdit/DiskImage.c
>index a50b52f..bc74a4f 100644
>--- a/ShellPkg/Library/UefiShellDebug1CommandsLib/HexEdit/DiskImage.c
>+++ b/ShellPkg/Library/UefiShellDebug1CommandsLib/HexEdit/DiskImage.c
>@@ -343,6 +343,7 @@ HDiskImageSave (
>
>   CONST EFI_DEVICE_PATH_PROTOCOL  *DevicePath;
>   EFI_DEVICE_PATH_PROTOCOL        *DupDevicePath;
>+  EFI_DEVICE_PATH_PROTOCOL        *DupDevicePathForFree;
>   EFI_BLOCK_IO_PROTOCOL           *BlkIo;
>   EFI_STATUS                      Status;
>   EFI_HANDLE                      Handle;
>@@ -364,12 +365,13 @@ HDiskImageSave (
>     return EFI_INVALID_PARAMETER;
>   }
>   DupDevicePath = DuplicateDevicePath(DevicePath);
>+  DupDevicePathForFree = DupDevicePath;
>
>   //
>   // get blkio interface
>   //
>   Status = gBS->LocateDevicePath(&gEfiBlockIoProtocolGuid,&DupDevicePath,&Handle);
>-  FreePool(DupDevicePath);
>+  FreePool(DupDevicePathForFree);
>   if (EFI_ERROR (Status)) {
> //    StatusBarSetStatusString (L"Read Disk Failed");
>     return Status;
>--
>2.6.3.windows.1