Re: [PATCH 2/2] mingw: enable DEP and ASLR
- Date: Tue, 30 Apr 2019 18:41:29 -0400 (DST)
- From: Johannes Schindelin <Johannes.Schindelin@xxxxxx>
- Subject: Re: [PATCH 2/2] mingw: enable DEP and ASLR
On Tue, 30 Apr 2019, Johannes Sixt wrote:
> [had to add Dscho as recipient manually, mind you]
I usually pick up responses to GitGitGadget patch series even if I am not
on explicit Cc: (but it might take a couple of days when I am too busy
elsewhere to read the Git mailing list).
> Am 29.04.19 um 23:56 schrieb İsmail Dönmez via GitGitGadget:
> > From: =?UTF-8?q?=C4=B0smail=20D=C3=B6nmez?= <ismail@xxxxxxxx>
> > 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@xxxxxxxx>
> > Signed-off-by: Johannes Schindelin <johannes.schindelin@xxxxxx>
> > ---
> > 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,$(MSYSTEM))
> > prefix = /mingw32
> > HOST_CPU = i686
> I'm a bit concerned that this breaks my debug sessions where I use -O0.
> But I'll test without -O0 before I really complain.
Weird. Jameson Miller also mentioned this very concern in an internal
I guess I'll do something like
ifneq (,$(findstring -O,$(filter-out -O0,$(CFLAGS))))
Does that work for you?