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From: Johannes Schindelin <Johannes.Schindelin@gmx.de>
To: Johannes Sixt <j6t@kdbg.org>
Cc: "İsmail Dönmez" <ismail@i10z.com>,
	"İsmail Dönmez via GitGitGadget" <gitgitgadget@gmail.com>,
	git@vger.kernel.org, "Junio C Hamano" <gitster@pobox.com>
Subject: Re: [PATCH 2/2] mingw: enable DEP and ASLR
Date: Tue, 30 Apr 2019 18:41:29 -0400 (DST)	[thread overview]
Message-ID: <nycvar.QRO.7.76.6.1904301838400.45@tvgsbejvaqbjf.bet> (raw)
In-Reply-To: <8e59dbf6-a339-74f3-4e60-e56b3817aea5@kdbg.org>

[-- Attachment #1: Type: text/plain, Size: 2286 bytes --]

Hi Hannes,

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@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
> >
>
> 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
review.

I guess I'll do something like

	ifneq (,$(findstring -O,$(filter-out -O0,$(CFLAGS))))

Does that work for you?

Ciao,
Dscho

  reply	other threads:[~2019-04-30 22:41 UTC|newest]

Thread overview: 16+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-04-29 21:56 [PATCH 0/2] Enable Data Execution Protection and Address Space Layout Randomization on Windows Johannes Schindelin via GitGitGadget
2019-04-29 21:56 ` [PATCH 1/2] mingw: do not let ld strip relocations İsmail Dönmez via GitGitGadget
2019-04-29 21:56 ` [PATCH 2/2] mingw: enable DEP and ASLR İsmail Dönmez via GitGitGadget
2019-04-30  6:26   ` Johannes Sixt
2019-04-30 22:41     ` Johannes Schindelin [this message]
2019-04-30 22:59       ` Johannes Sixt
2019-05-01 18:39       ` Alban Gruin
2019-05-01 23:36         ` brian m. carlson
2019-05-08 11:33           ` Johannes Schindelin
2019-05-08 11:33         ` Johannes Schindelin
2019-05-01 20:46       ` Jeff King
2019-05-01 22:02         ` Jonathan Nieder
2019-05-08 11:27           ` Johannes Schindelin
2019-05-08 11:30 ` [PATCH v2 0/2] Enable Data Execution Protection and Address Space Layout Randomization on Windows Johannes Schindelin via GitGitGadget
2019-05-08 11:30   ` [PATCH v2 1/2] mingw: do not let ld strip relocations İsmail Dönmez via GitGitGadget
2019-05-08 11:30   ` [PATCH v2 2/2] mingw: enable DEP and ASLR İsmail Dönmez via GitGitGadget

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