OvmfPkg: LoadLinuxLib: Zero kernel parameters instead of passing garbage

We're supposed to zero everything in the kernel bootparams that we don't explicitly initialise, other than the setup_header from 0x1f1 onwards for a precisely defined length, which is copied from the bzImage. We're *not* supposed to just pass the garbage that we happened to find in the bzImage file surrounding the setup_header. Contributed-under: TianoCore Contribution Agreement 1.0 Signed-off-by: David Woodhouse <[email protected]> Reviewed-by: Jordan Justen <[email protected]> git-svn-id: https://edk2.svn.sourceforge.net/svnroot/edk2/trunk/edk2@14052 6f19259b-4bc3-4df7-8a09-765794883524
hauzlin · Jan 16, 2013 · c61a56f · c61a56f
1 parent 38851e7
commit c61a56f
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Showing 3 changed files with 55 additions and 2 deletions.
diff --git a/OvmfPkg/Include/Library/LoadLinuxLib.h b/OvmfPkg/Include/Library/LoadLinuxLib.h
@@ -1,7 +1,7 @@
 /** @file
   Load/boot UEFI Linux.
 
-  Copyright (c) 2011 - 2012, Intel Corporation. All rights reserved.<BR>
+  Copyright (c) 2011 - 2013, Intel Corporation. All rights reserved.<BR>
   This program and the accompanying materials
   are licensed and made available under the terms and conditions of the BSD License
   which accompanies this distribution.  The full text of the license may be found at
@@ -94,6 +94,26 @@ LoadLinuxAllocateKernelSetupPages (
   );
 
 
+/**
+  Clears the uninitialised space before and after the struct setup_header
+  in the kernel setup image. The kernel requires that these be zeroed
+  unless explicitly initialised, so this function should be called after
+  the setup_header has been copied in from a bzImage, before setting up
+  anything else.
+
+  @param[in]     KernelSetup - The kernel setup image
+
+  @retval    EFI_SUCCESS - The Linux kernel setup was successfully initialized
+  @retval    EFI_INVALID_PARAMETER - KernelSetup was NULL
+  @retval    EFI_UNSUPPORTED - The Linux kernel is not supported
+
+**/
+EFI_STATUS
+EFIAPI
+LoadLinuxInitializeKernelSetup (
+  IN VOID        *KernelSetup
+  );
+
 /**
   Allocates pages for the kernel.
 

diff --git a/OvmfPkg/Library/LoadLinuxLib/Linux.c b/OvmfPkg/Library/LoadLinuxLib/Linux.c
@@ -119,6 +119,34 @@ LoadLinuxAllocateKernelSetupPages (
   }
 }
 
+EFI_STATUS
+EFIAPI
+LoadLinuxInitializeKernelSetup (
+  IN VOID        *KernelSetup
+  )
+{
+  EFI_STATUS                Status;
+  UINTN                     SetupEnd;
+  struct boot_params        *Bp;
+
+  Status = BasicKernelSetupCheck (KernelSetup);
+  if (EFI_ERROR (Status)) {
+    return Status;
+  }
+
+  Bp = (struct boot_params*) KernelSetup;
+
+  SetupEnd = 0x202 + (Bp->hdr.jump & 0xff);
+
+  //
+  // Clear all but the setup_header
+  //
+  ZeroMem (KernelSetup, 0x1f1);
+  ZeroMem (((UINT8 *)KernelSetup) + SetupEnd, 4096 - SetupEnd);
+  DEBUG ((EFI_D_INFO, "Cleared kernel setup 0-0x1f1, 0x%x-0x1000\n", SetupEnd));
+
+  return EFI_SUCCESS;
+}
 
 VOID*
 EFIAPI

diff --git a/OvmfPkg/Library/PlatformBdsLib/QemuKernel.c b/OvmfPkg/Library/PlatformBdsLib/QemuKernel.c
@@ -1,6 +1,6 @@
 /** @file
 
-  Copyright (c) 2006 - 2012, Intel Corporation. All rights reserved.<BR>
+  Copyright (c) 2006 - 2013, Intel Corporation. All rights reserved.<BR>
   This program and the accompanying materials
   are licensed and made available under the terms and conditions of the BSD License
   which accompanies this distribution.  The full text of the license may be found at
@@ -78,6 +78,11 @@ TryRunningQemuKernel (
     goto FreeAndReturn;
   }
 
+  Status = LoadLinuxInitializeKernelSetup (SetupBuf);
+  if (EFI_ERROR (Status)) {
+    goto FreeAndReturn;
+  }
+
   KernelInitialSize = LoadLinuxGetKernelSize (SetupBuf, KernelSize);
   if (KernelInitialSize == 0) {
     Status = EFI_UNSUPPORTED;