[PATCH 1/1] MdeModulePkg/RuntimeDxe: clear mVirtualMapMaxIndex

[PATCH 1/1] MdeModulePkg/RuntimeDxe: clear mVirtualMapMaxIndex

[Gerd Hoffmann]

When setting mVirtualMap to NULL also set mVirtualMapMaxIndex to 0.
Without that RuntimeDriverConvertPointer() will go search the ZeroPage
for EFI_MEMORY_DESCRIPTOR entries.

In case mVirtualMapMaxIndex happens to be small small enough that'll go
unnoticed, the search will not find anything and EFI_NOT_FOUND will be
returned.

In case mVirtualMapMaxIndex is big enough the search will reach the end
of the ZeroPage and trigger a page fault.

Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
---
 MdeModulePkg/Core/RuntimeDxe/Runtime.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/MdeModulePkg/Core/RuntimeDxe/Runtime.c b/MdeModulePkg/Core/RuntimeDxe/Runtime.c
index 2a541408731d..de8f2bfce0f8 100644
--- a/MdeModulePkg/Core/RuntimeDxe/Runtime.c
+++ b/MdeModulePkg/Core/RuntimeDxe/Runtime.c
@@ -365,7 +365,8 @@ RuntimeDriverSetVirtualAddressMap (
   //
   // mVirtualMap is only valid during SetVirtualAddressMap() call
   //
-  mVirtualMap = NULL;
+  mVirtualMap         = NULL;
+  mVirtualMapMaxIndex = 0;
 
   return EFI_SUCCESS;
 }
-- 
2.34.1

回复: [edk2-devel] [PATCH 1/1] MdeModulePkg/RuntimeDxe: clear mVirtualMapMaxIndex

[gaoliming]

Reviewed-by: Liming Gao <gaoliming@byosoft.com.cn>

> -----邮件原件-----
> 发件人: devel@edk2.groups.io <devel@edk2.groups.io> 代表 Gerd
> Hoffmann
> 发送时间: 2022年1月21日 20:59
> 收件人: devel@edk2.groups.io
> 抄送: Dandan Bi <dandan.bi@intel.com>; Pawel Polawski
> <ppolawsk@redhat.com>; Jian J Wang <jian.j.wang@intel.com>; Liming Gao
> <gaoliming@byosoft.com.cn>; Gerd Hoffmann <kraxel@redhat.com>
> 主题: [edk2-devel] [PATCH 1/1] MdeModulePkg/RuntimeDxe: clear
> mVirtualMapMaxIndex
> 
> When setting mVirtualMap to NULL also set mVirtualMapMaxIndex to 0.
> Without that RuntimeDriverConvertPointer() will go search the ZeroPage
> for EFI_MEMORY_DESCRIPTOR entries.
> 
> In case mVirtualMapMaxIndex happens to be small small enough that'll go
> unnoticed, the search will not find anything and EFI_NOT_FOUND will be
> returned.
> 
> In case mVirtualMapMaxIndex is big enough the search will reach the end
> of the ZeroPage and trigger a page fault.
> 
> Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
> ---
>  MdeModulePkg/Core/RuntimeDxe/Runtime.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/MdeModulePkg/Core/RuntimeDxe/Runtime.c
> b/MdeModulePkg/Core/RuntimeDxe/Runtime.c
> index 2a541408731d..de8f2bfce0f8 100644
> --- a/MdeModulePkg/Core/RuntimeDxe/Runtime.c
> +++ b/MdeModulePkg/Core/RuntimeDxe/Runtime.c
> @@ -365,7 +365,8 @@ RuntimeDriverSetVirtualAddressMap (
>    //
>    // mVirtualMap is only valid during SetVirtualAddressMap() call
>    //
> -  mVirtualMap = NULL;
> +  mVirtualMap         = NULL;
> +  mVirtualMapMaxIndex = 0;
> 
>    return EFI_SUCCESS;
>  }
> --
> 2.34.1
> 
> 
> 
> 
>