Re: [PATCH v2] configure: fix --enable-fuzzing linker failures

[Paolo Bonzini <pbonzini@redhat.com>]

On 21/02/21 18:45, Alexander Bulekov 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>
> ---
> v2: Fix a mistake in the added QEMU_LDFLAGS line
> 
>   configure | 10 ++++++++++
>   1 file changed, 10 insertions(+)
> 
> diff --git a/configure b/configure
> index a79b3746d4..19f2b88589 100755
> --- a/configure
> +++ b/configure
> @@ -6096,7 +6096,17 @@ if test "$fuzzing" = "yes" ; then
>     # If LIB_FUZZING_ENGINE is set, assume we are running on OSS-Fuzz, and the
>     # needed CFLAGS have already been provided
>     if test -z "${LIB_FUZZING_ENGINE+xxx}" ; then
> +    # Add CFLAGS to tell clang to add fuzzer-related instrumentation to all the
> +    # compiled code.
>       QEMU_CFLAGS="$QEMU_CFLAGS -fsanitize=fuzzer-no-link"
> +    # To build non-fuzzer binaries with --enable-fuzzing, link everything with
> +    # fsanitize=fuzzer-no-link. Otherwise, the linker will be unable to bind
> +    # the fuzzer-related callbacks added by instrumentation.
> +    QEMU_LDFLAGS="$QEMU_LDFLAGS -fsanitize=fuzzer-no-link"
> +    # For the actual fuzzer binaries, we need to link against the libfuzzer
> +    # library. Provide the flags for doing this in FUZZ_EXE_LDFLAGS. The meson
> +    # rule for the fuzzer adds these to the link_args. They need to be
> +    # configurable, to support OSS-Fuzz
>       FUZZ_EXE_LDFLAGS="-fsanitize=fuzzer"
>     else
>       FUZZ_EXE_LDFLAGS="$LIB_FUZZING_ENGINE"
> 

Queued, thanks.

Paolo