From 503248ccdf45c14d4040ce44163facdc212e4991 Mon Sep 17 00:00:00 2001 From: Laszlo Ersek Date: Tue, 1 Sep 2020 11:12:19 +0200 Subject: SecurityPkg/DxeImageVerificationLib: extract SecDataDirEnd, SecDataDirLeft MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit The following two quantities: SecDataDir->VirtualAddress + SecDataDir->Size SecDataDir->VirtualAddress + SecDataDir->Size - OffSet are used multiple times in DxeImageVerificationHandler(). Introduce helper variables for them: "SecDataDirEnd" and "SecDataDirLeft", respectively. This saves us multiple calculations and significantly simplifies the code. Note that all three summands above have type UINT32, therefore the new variables are also of type UINT32. This patch does not change behavior. (Note that the code already handles the case when the SecDataDir->VirtualAddress + SecDataDir->Size UINT32 addition overflows -- namely, in that case, the certificate loop is never entered, and the corruption check right after the loop fires.) Cc: Jian J Wang Cc: Jiewen Yao Cc: Min Xu Cc: Wenyi Xie Ref: https://bugzilla.tianocore.org/show_bug.cgi?id=2215 Signed-off-by: Laszlo Ersek Message-Id: <20200901091221.20948-2-lersek@redhat.com> Reviewed-by: Philippe Mathieu-Daudé Tested-by: Wenyi Xie Reviewed-by: Min M Xu Reviewed-by: Jiewen Yao --- .../DxeImageVerificationLib/DxeImageVerificationLib.c | 12 ++++++++---- 1 file changed, 8 insertions(+), 4 deletions(-) diff --git a/SecurityPkg/Library/DxeImageVerificationLib/DxeImageVerificationLib.c b/SecurityPkg/Library/DxeImageVerificationLib/DxeImageVerificationLib.c index b08fe24e85..377feebb20 100644 --- a/SecurityPkg/Library/DxeImageVerificationLib/DxeImageVerificationLib.c +++ b/SecurityPkg/Library/DxeImageVerificationLib/DxeImageVerificationLib.c @@ -1652,6 +1652,8 @@ DxeImageVerificationHandler ( UINT8 *AuthData; UINTN AuthDataSize; EFI_IMAGE_DATA_DIRECTORY *SecDataDir; + UINT32 SecDataDirEnd; + UINT32 SecDataDirLeft; UINT32 OffSet; CHAR16 *NameStr; RETURN_STATUS PeCoffStatus; @@ -1849,12 +1851,14 @@ DxeImageVerificationHandler ( // "Attribute Certificate Table". // The first certificate starts at offset (SecDataDir->VirtualAddress) from the start of the file. // + SecDataDirEnd = SecDataDir->VirtualAddress + SecDataDir->Size; for (OffSet = SecDataDir->VirtualAddress; - OffSet < (SecDataDir->VirtualAddress + SecDataDir->Size); + OffSet < SecDataDirEnd; OffSet += (WinCertificate->dwLength + ALIGN_SIZE (WinCertificate->dwLength))) { WinCertificate = (WIN_CERTIFICATE *) (mImageBase + OffSet); - if ((SecDataDir->VirtualAddress + SecDataDir->Size - OffSet) <= sizeof (WIN_CERTIFICATE) || - (SecDataDir->VirtualAddress + SecDataDir->Size - OffSet) < WinCertificate->dwLength) { + SecDataDirLeft = SecDataDirEnd - OffSet; + if (SecDataDirLeft <= sizeof (WIN_CERTIFICATE) || + SecDataDirLeft < WinCertificate->dwLength) { break; } @@ -1948,7 +1952,7 @@ DxeImageVerificationHandler ( } } - if (OffSet != (SecDataDir->VirtualAddress + SecDataDir->Size)) { + if (OffSet != SecDataDirEnd) { // // The Size in Certificate Table or the attribute certificate table is corrupted. // -- cgit v1.2.3