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On Thu, Jun 16, 2022 at 09:32:02PM +0100, Jonathan Wakely wrote: > It looks like clang has addressed this deficiency now: > > https://clang.llvm.org/docs/UndefinedBehaviorSanitizer.html#usage Thanks, that is roughly what I'd implement anyway and apparently they have it already since 2015, we've added the -fsanitize-undefined-trap-on-error support back in 2014 and didn't change it since then. As a small divergence from clang, I chose -fsanitize-undefined-trap-on-error to be a (deprecated) alias for -fsanitize-trap aka -fsanitize-trap=all rather thn -fsanitize-trap=undefined which seems to be what clang does, because for a deprecated option it is IMHO more important backwards compatibility with what gcc did over the past 8 years rather than clang compatibility. Some sanitizers (e.g. asan, lsan, tsan) don't support traps, -fsanitize-trap=address etc. will be rejected (if enabled at the end of command line), -fno-sanitize-trap= can be specified even for them. This is similar behavior to -fsanitize-recover=. One complication is vptr sanitization, which can't easily trap, as the whole slow path of the checking is inside of libubsan. Previously, -fsanitize=vptr -fsanitize-undefined-trap-on-error silently ignored vptr sanitization. This patch similarly to what clang does will accept -fsanitize-trap=all or -fsanitize-trap=undefined which enable the vptr bit as trapping and again that causes silent disabling of vptr sanitization, while -fsanitize-trap=vptr is rejected (already during option processing). 2022-06-18 Jakub Jelinek <jakub@redhat.com> gcc/ * common.opt (flag_sanitize_trap): New variable. (fsanitize-trap=, fsanitize-trap): New options. (fsanitize-undefined-trap-on-error): Change into deprecated alias for -fsanitize-trap=all. * opts.h (struct sanitizer_opts_s): Add can_trap member. * opts.cc (finish_options): Complain about unsupported -fsanitize-trap= options. (sanitizer_opts): Add can_trap values to all entries. (get_closest_sanitizer_option): Ignore -fsanitize-trap= options which have can_trap false. (parse_sanitizer_options): Add support for -fsanitize-trap=. For -fsanitize-trap=all, enable SANITIZE_UNDEFINED | SANITIZE_UNDEFINED_NONDEFAULT. Disallow -fsanitize-trap=vptr here. (common_handle_option): Handle OPT_fsanitize_trap_ and OPT_fsanitize_trap. * sanopt.cc (maybe_optimize_ubsan_null_ifn): Check flag_sanitize_trap & SANITIZE_{NULL,ALIGNMENT} instead of flag_sanitize_undefined_trap_on_error. * gcc.cc (sanitize_spec_function): Use flag_sanitize & ~flag_sanitize_trap instead of flag_sanitize and drop use of flag_sanitize_undefined_trap_on_error in "undefined" handling. * ubsan.cc (ubsan_instrument_unreachable): Use flag_sanitize_trap & SANITIZE_??? instead of flag_sanitize_undefined_trap_on_error. (ubsan_expand_bounds_ifn, ubsan_expand_null_ifn, ubsan_expand_objsize_ifn, ubsan_expand_ptr_ifn, ubsan_build_overflow_builtin, instrument_bool_enum_load, ubsan_instrument_float_cast, instrument_nonnull_arg, instrument_nonnull_return, instrument_builtin): Likewise. * doc/invoke.texi (-fsanitize-trap=, -fsanitize-trap): Document. (-fsanitize-undefined-trap-on-error): Document as deprecated alias of -fsanitize-trap. gcc/c-family/ * c-ubsan.cc (ubsan_instrument_division, ubsan_instrument_shift): Use flag_sanitize_trap & SANITIZE_??? instead of flag_sanitize_undefined_trap_on_error. If 2 sanitizers are involved and flag_sanitize_trap differs for them, emit __builtin_trap only for the comparison where trap is requested. (ubsan_instrument_vla, ubsan_instrument_return): Use lag_sanitize_trap & SANITIZE_??? instead of flag_sanitize_undefined_trap_on_error. gcc/cp/ * cp-ubsan.cc (cp_ubsan_instrument_vptr_p): Use flag_sanitize_trap & SANITIZE_VPTR instead of flag_sanitize_undefined_trap_on_error. gcc/testsuite/ * c-c++-common/ubsan/nonnull-4.c: Use -fsanitize-trap=all instead of -fsanitize-undefined-trap-on-error. * c-c++-common/ubsan/div-by-zero-4.c: Use -fsanitize-trap=signed-integer-overflow instead of -fsanitize-undefined-trap-on-error. * c-c++-common/ubsan/overflow-add-4.c: Use -fsanitize-trap=undefined instead of -fsanitize-undefined-trap-on-error. * c-c++-common/ubsan/pr56956.c: Likewise. * c-c++-common/ubsan/pr68142.c: Likewise. * c-c++-common/ubsan/pr80932.c: Use -fno-sanitize-trap=all -fsanitize-trap=shift,undefined instead of -fsanitize-undefined-trap-on-error. * c-c++-common/ubsan/align-8.c: Use -fsanitize-trap=alignment instead of -fsanitize-undefined-trap-on-error. |
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