Undefined behavior error: call to function visit_type_InetSocketAddress_members through pointer to incorrect function type Description of problem: When compiling QEMU with --extra-cflags=-fsanitize=undefined and --extra-cflags=-fno-sanitize-recover=undefined on a system that has Clang v17 or newer (e.g. on Fedora 39 or Fedora 40), the unit tests abort with an undefined behavior error. Steps to reproduce: 1. ``./configure --cc=clang --extra-cflags=-fsanitize=undefined --extra-cflags=-fno-sanitize-recover=undefined --target-list=x86_64-softmmu`` 2. ``make -j$(nproc)`` 3. ``make check-unit`` Additional information: test-io-channel-socket aborts with: ``` 74/103 qemu:unit / test-io-channel-socket ERROR 0.15s killed by signal 6 SIGABRT >>> G_TEST_BUILDDIR=/tmp/qemu-ubsan/tests/unit ASAN_OPTIONS=halt_on_error=1:abort_on_error=1:print_summary=1 UBSAN_OPTIONS=halt_on_error=1:abort_on_error=1:print_summary=1:print_stacktrace=1 MALLOC_PERTURB_=163 G_TEST_SRCDIR=tests/unit /tmp/qemu-ubsan/tests/unit/test-io-channel-socket --tap -k ―――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――― ✀ ―――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――― stderr: qapi/qapi-clone-visitor.c:188:5: runtime error: call to function visit_type_SocketAddress through pointer to incorrect function type 'bool (*)(struct Visitor *, const char *, void **, struct Error **)' /tmp/qemu-ubsan/qapi/qapi-visit-sockets.c:487: note: visit_type_SocketAddress defined here #0 0x5642aa2f7f3b in qapi_clone qapi/qapi-clone-visitor.c:188:5 #1 0x5642aa2c8ce5 in qio_channel_socket_listen_async io/channel-socket.c:285:18 #2 0x5642aa2b8903 in test_io_channel_setup_async tests/unit/test-io-channel-socket.c:116:5 #3 0x5642aa2b8204 in test_io_channel tests/unit/test-io-channel-socket.c:179:9 #4 0x5642aa2b8129 in test_io_channel_ipv4 tests/unit/test-io-channel-socket.c:323:5 #5 0x7f01212c0bbf (/lib64/libglib-2.0.so.0+0x8bbbf) (BuildId: 795136df3faa85587229ddc59d709f81d6f697df) #6 0x7f01212c0b2f (/lib64/libglib-2.0.so.0+0x8bb2f) (BuildId: 795136df3faa85587229ddc59d709f81d6f697df) #7 0x7f01212c0b2f (/lib64/libglib-2.0.so.0+0x8bb2f) (BuildId: 795136df3faa85587229ddc59d709f81d6f697df) #8 0x7f01212c0b2f (/lib64/libglib-2.0.so.0+0x8bb2f) (BuildId: 795136df3faa85587229ddc59d709f81d6f697df) #9 0x7f01212c10c9 in g_test_run_suite (/lib64/libglib-2.0.so.0+0x8c0c9) (BuildId: 795136df3faa85587229ddc59d709f81d6f697df) #10 0x7f01212c115f in g_test_run (/lib64/libglib-2.0.so.0+0x8c15f) (BuildId: 795136df3faa85587229ddc59d709f81d6f697df) #11 0x5642aa2b72ec in main tests/unit/test-io-channel-socket.c:613:12 #12 0x7f0120d2d087 in __libc_start_call_main (/lib64/libc.so.6+0x2a087) (BuildId: b098f1c75a76548bb230d8f551eae07a2aeccf06) #13 0x7f0120d2d14a in __libc_start_main@GLIBC_2.2.5 (/lib64/libc.so.6+0x2a14a) (BuildId: b098f1c75a76548bb230d8f551eae07a2aeccf06) #14 0x5642aa28cd04 in _start (tests/unit/test-io-channel-socket+0x69d04) (BuildId: eeaee2b8d62ce3aa77ab8b447916a40defd78dc6) SUMMARY: UndefinedBehaviorSanitizer: undefined-behavior qapi/qapi-clone-visitor.c:188:5 (test program exited with status code -6) ``` And ``test-char`` aborts with: ``` 99/103 qemu:unit / test-char ERROR 0.12s killed by signal 6 SIGABRT >>> G_TEST_BUILDDIR=/tmp/qemu-ubsan/tests/unit ASAN_OPTIONS=halt_on_error=1:abort_on_error=1:print_summary=1 UBSAN_OPTIONS=halt_on_error=1:abort_on_error=1:print_summary=1:print_stacktrace=1 MALLOC_PERTURB_=197 G_TEST_SRCDIR=tests/unit /tmp/qemu-ubsan/tests/unit/test-char --tap -k ―――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――― ✀ ―――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――― stderr: qapi/qapi-clone-visitor.c:202:5: runtime error: call to function visit_type_InetSocketAddress_members through pointer to incorrect function type 'bool (*)(struct Visitor *, void *, struct Error **)' /tmp/qemu-ubsan/qapi/qapi-visit-sockets.c:65: note: visit_type_InetSocketAddress_members defined here #0 0x55ee1d20ad60 in qapi_clone_members qapi/qapi-clone-visitor.c:202:5 #1 0x55ee1d24a993 in socket_address_flattenutil/qemu-sockets.c #2 0x55ee1d1f26f6 in qmp_chardev_open_udp chardev/char-udp.c:199:34 #3 0x55ee1d1f5254 in qemu_char_open chardev/char.c:271:9 #4 0x55ee1d1f5254 in chardev_new chardev/char.c:968:5 #5 0x55ee1d1f45fd in qemu_chardev_new chardev/char.c:998:11 #6 0x55ee1d1f45fd in qemu_chr_new_from_opts chardev/char.c:657:11 #7 0x55ee1d1f49ac in qemu_chr_new_noreplay chardev/char.c:703:11 #8 0x55ee1d1f4aed in qemu_chr_new_permit_mux_mon chardev/char.c:731:11 #9 0x55ee1d1b45b8 in char_udp_test_internal tests/unit/test-char.c:590:15 #10 0x7f3dd421abbf (/lib64/libglib-2.0.so.0+0x8bbbf) (BuildId: 795136df3faa85587229ddc59d709f81d6f697df) #11 0x7f3dd421ab2f (/lib64/libglib-2.0.so.0+0x8bb2f) (BuildId: 795136df3faa85587229ddc59d709f81d6f697df) #12 0x7f3dd421b0c9 in g_test_run_suite (/lib64/libglib-2.0.so.0+0x8c0c9) (BuildId: 795136df3faa85587229ddc59d709f81d6f697df) #13 0x7f3dd421b15f in g_test_run (/lib64/libglib-2.0.so.0+0x8c15f) (BuildId: 795136df3faa85587229ddc59d709f81d6f697df) #14 0x55ee1d1af6bd in main tests/unit/test-char.c:1579:12 #15 0x7f3dd3c3d087 in __libc_start_call_main (/lib64/libc.so.6+0x2a087) (BuildId: b098f1c75a76548bb230d8f551eae07a2aeccf06) #16 0x7f3dd3c3d14a in __libc_start_main@GLIBC_2.2.5 (/lib64/libc.so.6+0x2a14a) (BuildId: b098f1c75a76548bb230d8f551eae07a2aeccf06) #17 0x55ee1d184e34 in _start (/tmp/qemu-ubsan/tests/unit/test-char+0x78e34) (BuildId: afdf2ec9875e3011d3ff99174ec137dc79fff74e) SUMMARY: UndefinedBehaviorSanitizer: undefined-behavior .qapi/qapi-clone-visitor.c:202:5 (test program exited with status code -6) ``` This undefined behavior could likely also trigger issues with CFI or certain compilers/architectures like emscripten, so we should try to avoid this. See also https://github.com/systemd/systemd/issues/29972 or https://github.com/python/cpython/issues/111178 for discussions in other projects, and https://gitlab.com/qemu-project/qemu/-/issues/2345 for a similar problem in the QEMU lockable code.