[PATCH 2/2] mingw: enable DEP and ASLR

From: İsmail Dönmez via GitGitGadget <gitgitgadget@gmail.com>
Date: Apr 29, 2019, 21:56 UTC
Message-ID: <e142c1396ec3541486317819e885cf42be24af34.1556575015.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>

Enable DEP (Data Execution Prevention) and ASLR (Address Space Layout Randomization) support. This applies to both 32bit and 64bit builds and makes it substantially harder to exploit security holes in Git by offering a much more unpredictable attack surface.

ASLR interferes with GDB's ability to set breakpoints. A similar issue holds true when compiling with -O2 (in which case single-stepping is messed up because GDB cannot map the code back to the original source code properly). Therefore we simply enable ASLR only when an optimization flag is present in the CFLAGS, using it as an indicator that the developer does not want to debug in GDB anyway.

Signed-off-by: İsmail Dönmez <ismail@i10z.com>
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
---
 config.mak.uname | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/config.mak.uname b/config.mak.uname
index e7c7d14e5f..a9edcc5f0b 100644
--- a/config.mak.uname
+++ b/config.mak.uname
@@ -570,6 +570,12 @@ else
 	ifeq ($(shell expr "$(uname_R)" : '2\.'),2)
 		# MSys2
 		prefix = /usr/
+		# Enable DEP
+		BASIC_LDFLAGS += -Wl,--nxcompat
+		# Enable ASLR (unless debugging)
+		ifneq (,$(findstring -O,$(CFLAGS)))
+			BASIC_LDFLAGS += -Wl,--dynamicbase
+		endif
 		ifeq (MINGW32,$(MSYSTEM))
 			prefix = /mingw32
 			HOST_CPU = i686

-- 
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