Re: [PATCH 3/4] configure: add flag to enable SafeStack

[Daniele Buono]

Hi Stefan,

I would feel more confident by adding another check in configure to make
sure that the user didn't enable SafeStack manually through other means,
like manually setting the option through extra_cflags.
What do you think?

On 5/21/2020 5:52 AM, Stefan Hajnoczi wrote:
> On Wed, Apr 29, 2020 at 03:44:19PM -0400, Daniele Buono wrote:
> > This patch adds a flag to enable the SafeStack instrumentation provided
> > by LLVM.
> > The checks make sure that the compiler supports the flags, and that we
> > are using the proper coroutine implementation (coroutine-ucontext).
> > While SafeStack is supported only on Linux, NetBSD, FreeBSD and macOS,
> > we are not checking for the O.S. since this is already done by LLVM.
> >
> > Signed-off-by: Daniele Buono <address@hidden>
> > ---
> >   configure | 29 +++++++++++++++++++++++++++++
> >   1 file changed, 29 insertions(+)
>
> Great, this can become Patch 1 and it can set CONFIG_SAFESTACK as
> mentioned in my earlier reply.
>
> > diff --git a/configure b/configure
> > index 23b5e93752..f37e4ae0bd 100755
> > --- a/configure
> > +++ b/configure
> > @@ -302,6 +302,7 @@ audio_win_int=""
> >   libs_qga=""
> >   debug_info="yes"
> >   stack_protector=""
> > +safe_stack="no"
>
> The comment above this says:
>
>    # Always add --enable-foo and --disable-foo command line args.
>
> Please add --disable-safe-stack.