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@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 > > 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@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,$(MSYSTEM)) > >>> prefix = /mingw32 > >>> HOST_CPU = i686 > >>> > >> > >> I'm a bit concerned that this breaks my debug sessions where I use -O0. > >> But I'll test without -O0 before I really complain. > > > > Weird. Jameson Miller also mentioned this very concern in an internal > > review. > > > > I guess I'll do something like > > > > ifneq (,$(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
