[PATCH] configure: fix --enable-fuzzing linker failures

[PATCH] configure: fix --enable-fuzzing linker failures

[Alexander Bulekov]

With --enable-fuzzing, QEMU_CFLAGS include -fsanitize=fuzzer-no-link.
This should allow us to build non-fuzzer binaries using objects
instrumented for fuzzing. However, to do that, we also need to link with
-fsanitize=fuzzer-no-link. We were not doing that.

Reported-by: Li Qiang <liq3ea@163.com>
Signed-off-by: Alexander Bulekov <alxndr@bu.edu>
---
 configure | 1 +
 1 file changed, 1 insertion(+)

diff --git a/configure b/configure
index a79b3746d4..02aaea31c8 100755
--- a/configure
+++ b/configure
@@ -6097,6 +6097,7 @@ if test "$fuzzing" = "yes" ; then
   # needed CFLAGS have already been provided
   if test -z "${LIB_FUZZING_ENGINE+xxx}" ; then
     QEMU_CFLAGS="$QEMU_CFLAGS -fsanitize=fuzzer-no-link"
+    QEMU_LDFLAGS="$QEMU_CFLAGS -fsanitize=fuzzer-no-link"
     FUZZ_EXE_LDFLAGS="-fsanitize=fuzzer"
   else
     FUZZ_EXE_LDFLAGS="$LIB_FUZZING_ENGINE"
-- 
2.27.0

Re: [PATCH] configure: fix --enable-fuzzing linker failures

[Peter Maydell]

On Sun, 21 Feb 2021 at 16:03, Alexander Bulekov <alxndr@bu.edu> wrote:
>
> With --enable-fuzzing, QEMU_CFLAGS include -fsanitize=fuzzer-no-link.
> This should allow us to build non-fuzzer binaries using objects
> instrumented for fuzzing. However, to do that, we also need to link with
> -fsanitize=fuzzer-no-link. We were not doing that.
>
> Reported-by: Li Qiang <liq3ea@163.com>
> Signed-off-by: Alexander Bulekov <alxndr@bu.edu>
> ---
>  configure | 1 +
>  1 file changed, 1 insertion(+)
>
> diff --git a/configure b/configure
> index a79b3746d4..02aaea31c8 100755
> --- a/configure
> +++ b/configure
> @@ -6097,6 +6097,7 @@ if test "$fuzzing" = "yes" ; then
>    # needed CFLAGS have already been provided
>    if test -z "${LIB_FUZZING_ENGINE+xxx}" ; then
>      QEMU_CFLAGS="$QEMU_CFLAGS -fsanitize=fuzzer-no-link"
> +    QEMU_LDFLAGS="$QEMU_CFLAGS -fsanitize=fuzzer-no-link"

Did you mean  ="$QEMU_LDFLAGS ... ?

>      FUZZ_EXE_LDFLAGS="-fsanitize=fuzzer"

-- PMM

Re: [PATCH] configure: fix --enable-fuzzing linker failures

[Alexander Bulekov]

On 210221 1622, Peter Maydell wrote:
> On Sun, 21 Feb 2021 at 16:03, Alexander Bulekov <alxndr@bu.edu> wrote:
> >
> > With --enable-fuzzing, QEMU_CFLAGS include -fsanitize=fuzzer-no-link.
> > This should allow us to build non-fuzzer binaries using objects
> > instrumented for fuzzing. However, to do that, we also need to link with
> > -fsanitize=fuzzer-no-link. We were not doing that.
> >
> > Reported-by: Li Qiang <liq3ea@163.com>
> > Signed-off-by: Alexander Bulekov <alxndr@bu.edu>
> > ---
> >  configure | 1 +
> >  1 file changed, 1 insertion(+)
> >
> > diff --git a/configure b/configure
> > index a79b3746d4..02aaea31c8 100755
> > --- a/configure
> > +++ b/configure
> > @@ -6097,6 +6097,7 @@ if test "$fuzzing" = "yes" ; then
> >    # needed CFLAGS have already been provided
> >    if test -z "${LIB_FUZZING_ENGINE+xxx}" ; then
> >      QEMU_CFLAGS="$QEMU_CFLAGS -fsanitize=fuzzer-no-link"
> > +    QEMU_LDFLAGS="$QEMU_CFLAGS -fsanitize=fuzzer-no-link"
> 
> Did you mean  ="$QEMU_LDFLAGS ... ?

Yes... It somehow passed my build-test. Should I send a v2?

> 
> >      FUZZ_EXE_LDFLAGS="-fsanitize=fuzzer"
> 
> -- PMM

Re: [PATCH] configure: fix --enable-fuzzing linker failures

[Peter Maydell]

On Sun, 21 Feb 2021 at 16:28, Alexander Bulekov <alxndr@bu.edu> wrote:
>
> On 210221 1622, Peter Maydell wrote:
> > On Sun, 21 Feb 2021 at 16:03, Alexander Bulekov <alxndr@bu.edu> wrote:
> > >
> > > With --enable-fuzzing, QEMU_CFLAGS include -fsanitize=fuzzer-no-link.
> > > This should allow us to build non-fuzzer binaries using objects
> > > instrumented for fuzzing. However, to do that, we also need to link with
> > > -fsanitize=fuzzer-no-link. We were not doing that.
> > >
> > > Reported-by: Li Qiang <liq3ea@163.com>
> > > Signed-off-by: Alexander Bulekov <alxndr@bu.edu>
> > > ---
> > >  configure | 1 +
> > >  1 file changed, 1 insertion(+)
> > >
> > > diff --git a/configure b/configure
> > > index a79b3746d4..02aaea31c8 100755
> > > --- a/configure
> > > +++ b/configure
> > > @@ -6097,6 +6097,7 @@ if test "$fuzzing" = "yes" ; then
> > >    # needed CFLAGS have already been provided
> > >    if test -z "${LIB_FUZZING_ENGINE+xxx}" ; then
> > >      QEMU_CFLAGS="$QEMU_CFLAGS -fsanitize=fuzzer-no-link"
> > > +    QEMU_LDFLAGS="$QEMU_CFLAGS -fsanitize=fuzzer-no-link"
> >
> > Did you mean  ="$QEMU_LDFLAGS ... ?
>
> Yes... It somehow passed my build-test. Should I send a v2?

Yes, please.

> > >      FUZZ_EXE_LDFLAGS="-fsanitize=fuzzer"

It might also be helpful to have a brief comment explaining
why we need to set fuzzing related options in all three of
QEMU_CFLAGS, QEMU_LDFLAGS and FUZZ_EXE_LDFLAGS (ie what the
difference between them is).

-- PMM