From b9bdfc72853fe97bd24401f8873ca61524dd2dc6 Mon Sep 17 00:00:00 2001 From: Laszlo Ersek Date: Thu, 19 Nov 2020 11:53:39 +0100 Subject: MdeModulePkg/Core/Dxe: assert SectionInstance invariant in FindChildNode() MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit FindChildNode() has two callers: GetSection(), and FindChildNode() itself. - At the GetSection() call site, a positive (i.e., nonzero) SectionInstance is passed. This is because GetSection() takes a zero-based (UINTN) SectionInstance, and then passes Instance=(SectionInstance+1) to FindChildNode(). - For reaching the recursive FindChildNode() call site, a section type mismatch, or a section instance mismatch, is necessary. This means, respectively, that SectionInstance will either not have been decreased, or not to zero anyway, at the recursive FindChildNode() call site. Add two ASSERT()s to FindChildNode(), for expressing the (SectionSize>0) invariant. In turn, the invariant provides the explanation why, after the recursive call, a zero SectionInstance implies success. Capture it in a comment. Cc: Dandan Bi Cc: Hao A Wu Cc: Jian J Wang Cc: Liming Gao Cc: Philippe Mathieu-Daudé Signed-off-by: Laszlo Ersek Reviewed-by: Liming Gao Reviewed-by: Philippe Mathieu-Daudé Message-Id: <20201119105340.16225-2-lersek@redhat.com> --- .../Dxe/SectionExtraction/CoreSectionExtraction.c | 23 ++++++++++++++++------ 1 file changed, 17 insertions(+), 6 deletions(-) (limited to 'MdeModulePkg') diff --git a/MdeModulePkg/Core/Dxe/SectionExtraction/CoreSectionExtraction.c b/MdeModulePkg/Core/Dxe/SectionExtraction/CoreSectionExtraction.c index d678166db4..d7f7ef4274 100644 --- a/MdeModulePkg/Core/Dxe/SectionExtraction/CoreSectionExtraction.c +++ b/MdeModulePkg/Core/Dxe/SectionExtraction/CoreSectionExtraction.c @@ -952,8 +952,8 @@ CreateChildNode ( search. @param SearchType Indicates the type of section to search for. @param SectionInstance Indicates which instance of section to find. - This is an in/out parameter to deal with - recursions. + This is an in/out parameter and it is 1-based, + to deal with recursions. @param SectionDefinitionGuid Guid of section definition @param FoundChild Output indicating the child node that is found. @param FoundStream Output indicating which section stream the child @@ -988,6 +988,8 @@ FindChildNode ( EFI_STATUS ErrorStatus; EFI_STATUS Status; + ASSERT (*SectionInstance > 0); + CurrentChildNode = NULL; ErrorStatus = EFI_NOT_FOUND; @@ -1037,6 +1039,11 @@ FindChildNode ( } } + // + // Type mismatch, or we haven't found the desired instance yet. + // + ASSERT (*SectionInstance > 0); + if (CurrentChildNode->EncapsulatedStreamHandle != NULL_STREAM_HANDLE) { // // If the current node is an encapsulating node, recurse into it... @@ -1050,16 +1057,20 @@ FindChildNode ( &RecursedFoundStream, AuthenticationStatus ); - // - // If the status is not EFI_SUCCESS, just save the error code and continue - // to find the request child node in the rest stream. - // if (*SectionInstance == 0) { + // + // The recursive FindChildNode() call decreased (*SectionInstance) to + // zero. + // ASSERT_EFI_ERROR (Status); *FoundChild = RecursedChildNode; *FoundStream = RecursedFoundStream; return EFI_SUCCESS; } else { + // + // If the status is not EFI_SUCCESS, just save the error code and + // continue to find the request child node in the rest stream. + // ErrorStatus = Status; } } else if ((CurrentChildNode->Type == EFI_SECTION_GUID_DEFINED) && (SearchType != EFI_SECTION_GUID_DEFINED)) { -- cgit v1.2.3