-- Best regards, LIU Hao
From d9bcae01bb0cbfaa8b6d35ab5dd6d5e7b9b98edd Mon Sep 17 00:00:00 2001 From: LIU Hao <lh_mo...@126.com> Date: Tue, 11 Feb 2025 10:34:14 +0800 Subject: [PATCH] crt/delayimp: Make an IAT entry writeable before modifying it Since Binutils 2.44, the import address table (abbr. IAT) is now read-only, in alignment with Microsoft LINK and LLD. This commit serves two purposes: First, at the moment, DLLTOOL, when generating a delay-import library, mistakenly places delay-import pointers in the ordinary read-only IAT, which can cause access violation if such functions are called. Eventually DLLTOOL has to be fixed, but nevertheless this commit is a kludge for such broken import libraries to be usable. Second, in the future, if `IMAGE_GUARD_PROTECT_DELAYLOAD_IAT` is specified in `GuardFlags` of the load config directory of an image, the delay-load IAT can also be made read-only, which may also require this change. Reference: https://sourceware.org/git/?p=binutils-gdb.git;a=commitdiff;h=db00f6c3aceabbf03acdb69e74b59b2d2b043cd7 Signed-off-by: LIU Hao <lh_mo...@126.com> --- mingw-w64-crt/misc/delayimp.c | 11 ++++++++++- 1 file changed, 10 insertions(+), 1 deletion(-) diff --git a/mingw-w64-crt/misc/delayimp.c b/mingw-w64-crt/misc/delayimp.c index caa6166f0..d92e6b2d4 100644 --- a/mingw-w64-crt/misc/delayimp.c +++ b/mingw-w64-crt/misc/delayimp.c @@ -131,6 +131,8 @@ static int WINAPI FLoadedAtPreferredAddress(PIMAGE_NT_HEADERS pinh,HMODULE hmod) /*typedef unsigned long *PULONG_PTR;*/ #endif +static CRITICAL_SECTION gDelayLoadLock = { .LockCount = -1 }; + FARPROC WINAPI __delayLoadHelper2(PCImgDelayDescr pidd,FARPROC *ppfnIATEntry); FARPROC WINAPI __delayLoadHelper2(PCImgDelayDescr pidd,FARPROC *ppfnIATEntry) @@ -147,7 +149,9 @@ FARPROC WINAPI __delayLoadHelper2(PCImgDelayDescr pidd,FARPROC *ppfnIATEntry) unsigned iIAT, iINT; PCImgThunkData pitd; FARPROC pfnRet; - + DWORD dwOldProtect; + WINBOOL bUnprotected; + if(!(idd.grAttrs & dlattrRva)) { PDelayLoadInfo rgpdli[1] = { &dli}; RaiseException(VcppException(ERROR_SEVERITY_ERROR,ERROR_INVALID_PARAMETER),0,1,(PULONG_PTR)(rgpdli)); @@ -217,7 +221,12 @@ FARPROC WINAPI __delayLoadHelper2(PCImgDelayDescr pidd,FARPROC *ppfnIATEntry) } } SetEntryHookBypass: + EnterCriticalSection(&gDelayLoadLock); + bUnprotected = VirtualProtect(ppfnIATEntry, sizeof(FARPROC), PAGE_READWRITE, &dwOldProtect); *ppfnIATEntry = pfnRet; + if(bUnprotected && dwOldProtect != PAGE_READWRITE) + VirtualProtect(ppfnIATEntry, sizeof(FARPROC), dwOldProtect, &dwOldProtect); + LeaveCriticalSection(&gDelayLoadLock); HookBypass: if(__pfnDliNotifyHook2) { dli.dwLastError = 0; -- 2.48.1
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