[edk2-devel] [PATCH 3/3] SecurityPkg/DxeImageVerificationLib: catch alignment overflow (CVE-2019-14562)

[wenyi,xie via groups.io]

On 2020/9/1 17:12, Laszlo Ersek wrote:
> The DxeImageVerificationHandler() function currently checks whether
> "SecDataDir" has enough room for "WinCertificate->dwLength". However, for
> advancing "OffSet", "WinCertificate->dwLength" is aligned to the next
> multiple of 8. If "WinCertificate->dwLength" is large enough, the
> alignment will return 0, and "OffSet" will be stuck at the same value.
> 
> Check whether "SecDataDir" has room left for both
> "WinCertificate->dwLength" and the alignment.
> 
> Cc: Jian J Wang <jian.j.wang at intel.com>
> Cc: Jiewen Yao <jiewen.yao at intel.com>
> Cc: Min Xu <min.m.xu at intel.com>
> Cc: Wenyi Xie <xiewenyi2 at huawei.com>
> Ref: https://bugzilla.tianocore.org/show_bug.cgi?id=2215
> Signed-off-by: Laszlo Ersek <lersek at redhat.com>

Tested-by: Wenyi Xie <xiewenyi2 at huawei.com>

> ---
>  SecurityPkg/Library/DxeImageVerificationLib/DxeImageVerificationLib.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
> 
> diff --git a/SecurityPkg/Library/DxeImageVerificationLib/DxeImageVerificationLib.c b/SecurityPkg/Library/DxeImageVerificationLib/DxeImageVerificationLib.c
> index 100739eb3eb6..11154b6cc58a 100644
> --- a/SecurityPkg/Library/DxeImageVerificationLib/DxeImageVerificationLib.c
> +++ b/SecurityPkg/Library/DxeImageVerificationLib/DxeImageVerificationLib.c
> @@ -1860,7 +1860,9 @@ DxeImageVerificationHandler (
>        break;
>      }
>      WinCertificate = (WIN_CERTIFICATE *) (mImageBase + OffSet);
> -    if (SecDataDirLeft < WinCertificate->dwLength) {
> +    if (SecDataDirLeft < WinCertificate->dwLength ||
> +        (SecDataDirLeft - WinCertificate->dwLength <
> +         ALIGN_SIZE (WinCertificate->dwLength))) {
>        break;
>      }
>  
> 


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