[PATCH 1/2] mingw: do not let ld strip relocations

From: İsmail Dönmez via GitGitGadget <gitgitgadget@gmail.com>
Date: Apr 29, 2019, 21:56 UTC
Message-ID: <e6acdba58659d6176a03037aeb63b0ba84e126ff.1556575015.git.gitgitgadget@gmail.com>
In-Reply-To: <pull.134.git.gitgitgadget@gmail.com>

From: =?UTF-8?q?=C4=B0smail=20D=C3=B6nmez?= <ismail@i10z.com>

This is the first step for enabling ASLR (Address Space Layout Randomization) support. We want to enable ASLR for better protection against exploiting security holes in Git: it makes it harder to attack software by making code addresses unpredictable.

The problem fixed by this commit is that `ld.exe` seems to be stripping relocations which in turn will break ASLR support. We just make sure it's not stripping the main executable entry.

Signed-off-by: İsmail Dönmez <ismail@i10z.com>
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
---
 config.mak.uname | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/config.mak.uname b/config.mak.uname
index b37fa8424c..e7c7d14e5f 100644
--- a/config.mak.uname
+++ b/config.mak.uname
@@ -573,10 +573,12 @@ else
 		ifeq (MINGW32,$(MSYSTEM))
 			prefix = /mingw32
 			HOST_CPU = i686
+			BASIC_LDFLAGS += -Wl,--pic-executable,-e,_mainCRTStartup
 		endif
 		ifeq (MINGW64,$(MSYSTEM))
 			prefix = /mingw64
 			HOST_CPU = x86_64
+			BASIC_LDFLAGS += -Wl,--pic-executable,-e,mainCRTStartup
 		else
 			COMPAT_CFLAGS += -D_USE_32BIT_TIME_T
 			BASIC_LDFLAGS += -Wl,--large-address-aware

-- 
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