Re: [PATCH] build: Use meson b_sanitize option for sanitizers

["Daniel P. Berrangé" <berrange@redhat.com>]

On Tue, Jun 23, 2026 at 03:46:59PM +0000, Nabih Estefan wrote:
> Refactor sanitizer configuration to use Meson's built-in `b_sanitize`
> option instead of manually adding flags to `qemu_cflags` and `qemu_ldflags`.
> This ensures that sanitizer flags are correctly passed to both C and Rust
> targets, fixing linker errors when Rust and UBSan are both enabled.

Our clang-user and clang-system CI jobs both build with --enable-ubsan
but don't enable Rust. I wonder if we can / should enable Rust in those
CI jobs to validate this scenario.

> 
> Explicitly parse `--enable-ubsan`, `--enable-asan`, and `--enable-tsan`
> in `configure` and map them to `-Db_sanitize` meson option. Remove
> redundant custom options from `meson_options.txt`.
> 
> How to test:
> `./configure --target-list=aarch64-softmmu --enable-ubsan --enable-rust
>  && make -j all`
> 
> Before this change it will fail at the end of make, since the linker will have
> different flags, after this change it will link properly
> 
> Signed-off-by: Nabih Estefan <nabihestefan@google.com>
> ---
>  configure                           | 35 ++++++++++++++++++
>  linux-user/meson.build              |  6 +++-
>  meson.build                         | 55 +++++++++++++----------------
>  meson_options.txt                   |  7 +---
>  scripts/meson-buildoptions.sh       |  9 -----
>  tests/functional/x86_64/meson.build |  2 +-
>  tests/unit/meson.build              |  2 +-
>  7 files changed, 67 insertions(+), 49 deletions(-)
> 
> diff --git a/configure b/configure
> index d8bc10060e..579df2f2c8 100755
> --- a/configure
> +++ b/configure
> @@ -281,6 +281,9 @@ cfi="false"
>  # which requires knowing whether --static is enabled.
>  pie=""
>  static="no"
> +ubsan="false"
> +asan="false"
> +tsan="false"
>  
>  # Preferred compiler:
>  #  ${CC} (if set)
> @@ -746,6 +749,18 @@ for opt do
>    ;;
>    --wasm64-32bit-address-limit)
>    ;;
> +  --enable-ubsan) ubsan="true"
> +  ;;
> +  --disable-ubsan) ubsan="false"
> +  ;;
> +  --enable-asan) asan="true"
> +  ;;
> +  --disable-asan) asan="false"
> +  ;;
> +  --enable-tsan) tsan="true"
> +  ;;
> +  --disable-tsan) tsan="false"
> +  ;;
>    # everything else has the same name in configure and meson
>    --*) meson_option_parse "$opt" "$optarg"
>    ;;
> @@ -1939,6 +1954,26 @@ if test "$skip_meson" = no; then
>  
>    # QEMU options
>    test "$rust" != "disabled" && meson_option_add "-Drust=$rust"
> +
> +  # Translate asan/ubsan/tsan to b_sanitize
> +  sanitizers=""
> +  if test "$ubsan" = "true" && test "$asan" = "true"; then
> +    sanitizers="undefined,address"
> +  elif test "$ubsan" = "true"; then
> +    sanitizers="undefined"
> +  elif test "$asan" = "true"; then
> +    sanitizers="address"
> +  fi
> +  if test "$tsan" = "true"; then
> +    if test -n "$sanitizers"; then
> +      error_exit "TSAN is not supported with other sanitizers"
> +    fi
> +    sanitizers="thread"
> +  fi
> +  if test -n "$sanitizers"; then
> +    meson_option_add "-Db_sanitize=$sanitizers"
> +  fi
> +
>    test "$cfi" != false && meson_option_add "-Dcfi=$cfi" "-Db_lto=$cfi"
>    test "$docs" != auto && meson_option_add "-Ddocs=$docs"
>    test -n "${LIB_FUZZING_ENGINE+xxx}" && meson_option_add "-Dfuzzing_engine=$LIB_FUZZING_ENGINE"
> diff --git a/linux-user/meson.build b/linux-user/meson.build
> index 332847a621..d48887efb6 100644
> --- a/linux-user/meson.build
> +++ b/linux-user/meson.build
> @@ -34,8 +34,12 @@ endif
>  
>  syscall_nr_generators = {}
>  
> +# gen-vdso doesn't play well with sanitizers. It originally didn't get them due
> +# to the way we passed sanitizer flags. Now that they're being passed through
> +# meson wen need to override it.
>  gen_vdso_exe = executable('gen-vdso', 'gen-vdso.c',
> -                          native: true, build_by_default: false)
> +                          native: true, build_by_default: false,
> +                          override_options: ['b_sanitize=none'])
>  gen_vdso = generator(gen_vdso_exe, output: '@BASENAME@.c.inc',
>                       arguments: ['-o', '@OUTPUT@', '@EXTRA_ARGS@', '@INPUT@'])
>  
> diff --git a/meson.build b/meson.build
> index e026851309..417c27002c 100644
> --- a/meson.build
> +++ b/meson.build
> @@ -541,43 +541,35 @@ if get_option('safe_stack') and coroutine_backend != 'ucontext'
>    error('SafeStack is only supported with the ucontext coroutine backend')
>  endif
>  
> -if get_option('asan')
> -  if cc.has_argument('-fsanitize=address')
> -    qemu_cflags = ['-fsanitize=address'] + qemu_cflags
> -    qemu_ldflags = ['-fsanitize=address'] + qemu_ldflags
> -  else
> -    error('Your compiler does not support -fsanitize=address')
> -  endif
> +sanitize = get_option('b_sanitize')
> +
> +if sanitize.contains('address')
> +  # Meson handles -fsanitize=address automatically
>  endif
>  
> -if get_option('ubsan')
> +if sanitize.contains('undefined')
>    # Detect static linking issue with ubsan:
>    # https://gcc.gnu.org/bugzilla/show_bug.cgi?id=84285
> -  if cc.links('int main(int argc, char **argv) { return argc + 1; }',
> -              args: [qemu_ldflags, '-fsanitize=undefined'])
> -    qemu_cflags += ['-fsanitize=undefined']
> -    qemu_ldflags += ['-fsanitize=undefined']
> -
> -    # Suppress undefined behaviour from function call to mismatched type.
> -    # In addition, tcg prologue does not emit function type prefix
> -    # required by function call sanitizer.
> -    if cc.has_argument('-fno-sanitize=function')
> -      qemu_cflags += ['-fno-sanitize=function']
> -    endif
> -  else
> +  if not cc.links('int main(int argc, char **argv) { return argc + 1; }',
> +                  args: [qemu_ldflags, '-fsanitize=undefined'])
>      error('Your compiler does not support -fsanitize=undefined')
>    endif
> +
> +  # Suppress undefined behaviour from function call to mismatched type.
> +  # In addition, tcg prologue does not emit function type prefix
> +  # required by function call sanitizer.
> +  if cc.has_argument('-fno-sanitize=function')
> +    qemu_cflags += ['-fno-sanitize=function']
> +  endif
>  endif
>  
> -# Thread sanitizer is, for now, much noisier than the other sanitizers;
> -# keep it separate until that is not the case.
> -if get_option('tsan')
> -  if get_option('asan') or get_option('ubsan')
> +if sanitize.contains('thread')
> +  if sanitize.contains('address') or sanitize.contains('undefined')
>      error('TSAN is not supported with other sanitizers')
>    endif
>    if not cc.has_function('__tsan_create_fiber',
> -                         args: '-fsanitize=thread',
> -                         prefix: '#include <sanitizer/tsan_interface.h>')
> +                          args: '-fsanitize=thread',
> +                          prefix: '#include <sanitizer/tsan_interface.h>')
>      error('Cannot enable TSAN due to missing fiber annotation interface')
>    endif
>    tsan_warn_suppress = []
> @@ -588,8 +580,7 @@ if get_option('tsan')
>    if cc.has_argument('-Wno-tsan')
>      tsan_warn_suppress = ['-Wno-tsan']
>    endif
> -  qemu_cflags = ['-fsanitize=thread'] + tsan_warn_suppress + qemu_cflags
> -  qemu_ldflags = ['-fsanitize=thread'] + qemu_ldflags
> +  qemu_cflags += tsan_warn_suppress
>  endif
>  
>  # Detect support for PT_GNU_RELRO + DT_BIND_NOW.
> @@ -2482,7 +2473,7 @@ if have_tcg
>    config_host_data.set('CONFIG_TCG_INTERPRETER', tcg_arch == 'tci')
>  endif
>  config_host_data.set('CONFIG_TPM', have_tpm)
> -config_host_data.set('CONFIG_TSAN', get_option('tsan'))
> +config_host_data.set('CONFIG_TSAN', sanitize.contains('thread'))
>  config_host_data.set('CONFIG_USB_LIBUSB', libusb.found())
>  config_host_data.set('CONFIG_VDE', vde.found())
>  config_host_data.set('CONFIG_VHOST', have_vhost)
> @@ -2639,7 +2630,7 @@ if rdma.found()
>  endif
>  
>  have_asan_fiber = false
> -if get_option('asan') and \
> +if sanitize.contains('address') and \
>     not cc.has_function('__sanitizer_start_switch_fiber',
>                           args: '-fsanitize=address',
>                           prefix: '#include <sanitizer/asan_interface.h>')
> @@ -4768,7 +4759,9 @@ summary_info += {'memory allocator':  get_option('malloc')}
>  summary_info += {'avx2 optimization': config_host_data.get('CONFIG_AVX2_OPT')}
>  summary_info += {'avx512bw optimization': config_host_data.get('CONFIG_AVX512BW_OPT')}
>  summary_info += {'gcov':              get_option('b_coverage')}
> -summary_info += {'thread sanitizer':  get_option('tsan')}
> +summary_info += {'address sanitizer': sanitize.contains('address')}
> +summary_info += {'undefined behavior sanitizer': sanitize.contains('undefined')}
> +summary_info += {'thread sanitizer':  sanitize.contains('thread')}
>  summary_info += {'CFI support':       get_option('cfi')}
>  if get_option('cfi')
>    summary_info += {'CFI debug support': get_option('cfi_debug')}
> diff --git a/meson_options.txt b/meson_options.txt
> index a07cb47d35..d61c0241cc 100644
> --- a/meson_options.txt
> +++ b/meson_options.txt
> @@ -99,12 +99,7 @@ option('tcg_interpreter', type: 'boolean', value: false,
>         description: 'TCG with bytecode interpreter (slow)')
>  option('safe_stack', type: 'boolean', value: false,
>         description: 'SafeStack Stack Smash Protection (requires clang/llvm and coroutine backend ucontext)')
> -option('asan', type: 'boolean', value: false,
> -       description: 'enable address sanitizer')
> -option('ubsan', type: 'boolean', value: false,
> -       description: 'enable undefined behaviour sanitizer')
> -option('tsan', type: 'boolean', value: false,
> -       description: 'enable thread sanitizer')
> +
>  option('stack_protector', type: 'feature', value: 'auto',
>         description: 'compiler-provided stack protection')
>  option('cfi', type: 'boolean', value: false,
> diff --git a/scripts/meson-buildoptions.sh b/scripts/meson-buildoptions.sh
> index c003985047..8d3b992ed7 100644
> --- a/scripts/meson-buildoptions.sh
> +++ b/scripts/meson-buildoptions.sh
> @@ -21,7 +21,6 @@ meson_options_help() {
>    printf "%s\n" '  --disable-relocatable    toggle relocatable install'
>    printf "%s\n" '  --docdir=VALUE           Base directory for documentation installation'
>    printf "%s\n" '                           (can be empty) [share/doc]'
> -  printf "%s\n" '  --enable-asan            enable address sanitizer'
>    printf "%s\n" '  --enable-block-drv-whitelist-in-tools'
>    printf "%s\n" '                           use block whitelist also in tools instead of only'
>    printf "%s\n" '                           QEMU'
> @@ -54,8 +53,6 @@ meson_options_help() {
>    printf "%s\n" '  --enable-trace-backends=CHOICES'
>    printf "%s\n" '                           Set available tracing backends [log] (choices:'
>    printf "%s\n" '                           dtrace/ftrace/log/nop/simple/syslog/ust)'
> -  printf "%s\n" '  --enable-tsan            enable thread sanitizer'
> -  printf "%s\n" '  --enable-ubsan           enable undefined behaviour sanitizer'
>    printf "%s\n" '  --firmwarepath=VALUES    search PATH for firmware files [share/qemu-'
>    printf "%s\n" '                           firmware]'
>    printf "%s\n" '  --iasl=VALUE             Path to ACPI disassembler'
> @@ -238,8 +235,6 @@ _meson_option_parse() {
>      --disable-af-xdp) printf "%s" -Daf_xdp=disabled ;;
>      --enable-alsa) printf "%s" -Dalsa=enabled ;;
>      --disable-alsa) printf "%s" -Dalsa=disabled ;;
> -    --enable-asan) printf "%s" -Dasan=true ;;
> -    --disable-asan) printf "%s" -Dasan=false ;;
>      --enable-attr) printf "%s" -Dattr=enabled ;;
>      --disable-attr) printf "%s" -Dattr=disabled ;;
>      --audio-drv-list=*) quote_sh "-Daudio_drv_list=$2" ;;
> @@ -521,14 +516,10 @@ _meson_option_parse() {
>      --disable-tpm) printf "%s" -Dtpm=disabled ;;
>      --enable-trace-backends=*) quote_sh "-Dtrace_backends=$2" ;;
>      --with-trace-file=*) quote_sh "-Dtrace_file=$2" ;;
> -    --enable-tsan) printf "%s" -Dtsan=true ;;
> -    --disable-tsan) printf "%s" -Dtsan=false ;;
>      --enable-u2f) printf "%s" -Du2f=enabled ;;
>      --disable-u2f) printf "%s" -Du2f=disabled ;;
>      --enable-uadk) printf "%s" -Duadk=enabled ;;
>      --disable-uadk) printf "%s" -Duadk=disabled ;;
> -    --enable-ubsan) printf "%s" -Dubsan=true ;;
> -    --disable-ubsan) printf "%s" -Dubsan=false ;;
>      --enable-usb-redir) printf "%s" -Dusb_redir=enabled ;;
>      --disable-usb-redir) printf "%s" -Dusb_redir=disabled ;;
>      --enable-valgrind) printf "%s" -Dvalgrind=enabled ;;
> diff --git a/tests/functional/x86_64/meson.build b/tests/functional/x86_64/meson.build
> index 1ed10ad6c2..54af748f15 100644
> --- a/tests/functional/x86_64/meson.build
> +++ b/tests/functional/x86_64/meson.build
> @@ -24,7 +24,7 @@ tests_x86_64_system_quick = [
>  # interacts badly with the sanitizer; this means the memlock
>  # test (which checks via /proc for whether pages were locked)
>  # will always fail on a sanitizer build, so don't run it.
> -if not get_option('asan')
> +if not sanitize.contains('address')
>    tests_x86_64_system_quick += [ 'memlock' ]
>  endif
>  
> diff --git a/tests/unit/meson.build b/tests/unit/meson.build
> index 01cc540a45..b0ba64d0ec 100644
> --- a/tests/unit/meson.build
> +++ b/tests/unit/meson.build
> @@ -147,7 +147,7 @@ if have_system
>    # Some tests: test-char, test-qdev-global-props, and test-qga,
>    # are not runnable under TSan due to a known issue.
>    # https://github.com/google/sanitizers/issues/1116
> -  if not get_option('tsan')
> +  if not sanitize.contains('thread')
>      if host_os != 'windows'
>          tests += {
>            'test-char': ['socket-helpers.c', qom, io, chardev]
> -- 
> 2.55.0.rc0.786.g65d90a0328-goog
> 

With regards,
Daniel
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