From: Johannes Schindelin <Johannes.Schindelin@gmx.de>
To: Alban Gruin <alban.gruin@gmail.com>
Cc: "Johannes Sixt" <j6t@kdbg.org>, "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: Wed, 8 May 2019 13:33:08 +0200 (DST) [thread overview]
Message-ID: <nycvar.QRO.7.76.6.1905081331060.44@tvgsbejvaqbjf.bet> (raw)
In-Reply-To: <2e7be484-74d7-7258-954e-3a4a34a36c01@gmail.com>
[-- Attachment #1: Type: text/plain, Size: 3273 bytes --]
Hi Alban,
On Wed, 1 May 2019, Alban Gruin wrote:
> Le 01/05/2019 à 00:41, Johannes Schindelin a écrit :
> >
> > 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
>
> I don’t know if it stands true when combined with something like -ggdb3,
> but I may be very wrong. Feel free to correct me.
Possibly, but that makes my job here harder, so I won't even try right now
;-)
> >>> 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))))
> >
>
> -Og also exists to debug[0], even if it’s far less known.
Good point.
> Perhaps it’s better to check for -g (and its variants[1]) as the user
> clearly states their intent to debug the resulting binary, rather than
> checking for special cases.
I don't think we can use that, as we specifically build Git for Windows
with optimization *and* with debug symbols (and then use cv2pdb to extract
those debug symbols into external .pdb files for use with advanced
post-mortem tools, i.e. we do *not* need to single-step).
Thanks,
Dscho
next prev parent reply other threads:[~2019-05-08 11:33 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
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 [this message]
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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