libbpf: Streamline bpf_attr and perf_event_attr initialization

Make sure that entire libbpf code base is initializing bpf_attr and
perf_event_attr with memset(0). Also for bpf_attr make sure we
clear and pass to kernel only relevant parts of bpf_attr. bpf_attr is
a huge union of independent sub-command attributes, so there is no need
to clear and pass entire union bpf_attr, which over time grows quite
a lot and for most commands this growth is completely irrelevant.

Few cases where we were relying on compiler initialization of BPF UAPI
structs (like bpf_prog_info, bpf_map_info, etc) with `= {};` were
switched to memset(0) pattern for future-proofing.

Signed-off-by: Andrii Nakryiko <[e-mail]>
Signed-off-by: Daniel Borkmann <[e-mail]>
Acked-by: Hao Luo <[e-mail]>
Link: https://lore.kernel.org/bpf/[e-mail]

tools/lib/bpf/bpf.c

···
  */
 int probe_memcg_account(void)
 {
-	const size_t prog_load_attr_sz = offsetofend(union bpf_attr, attach_btf_obj_fd);
+	const size_t attr_sz = offsetofend(union bpf_attr, attach_btf_obj_fd);
 	struct bpf_insn insns[] = {
 		BPF_EMIT_CALL(BPF_FUNC_ktime_get_coarse_ns),
 		BPF_EXIT_INSN(),
···
 	int prog_fd;
 
 	/* attempt loading freplace trying to use custom BTF */
-	memset(&attr, 0, prog_load_attr_sz);
+	memset(&attr, 0, attr_sz);
 	attr.prog_type = BPF_PROG_TYPE_SOCKET_FILTER;
 	attr.insns = ptr_to_u64(insns);
 	attr.insn_cnt = insn_cnt;
 	attr.license = ptr_to_u64("GPL");
 
-	prog_fd = sys_bpf_fd(BPF_PROG_LOAD, &attr, prog_load_attr_sz);
+	prog_fd = sys_bpf_fd(BPF_PROG_LOAD, &attr, attr_sz);
 	if (prog_fd >= 0) {
 		close(prog_fd);
 		return 1;
···
 		  const struct bpf_insn *insns, size_t insn_cnt,
 		  const struct bpf_prog_load_opts *opts)
 {
+	const size_t attr_sz = offsetofend(union bpf_attr, fd_array);
 	void *finfo = NULL, *linfo = NULL;
 	const char *func_info, *line_info;
 	__u32 log_size, log_level, attach_prog_fd, attach_btf_obj_fd;
···
 	if (attempts == 0)
 		attempts = PROG_LOAD_ATTEMPTS;
 
-	memset(&attr, 0, sizeof(attr));
+	memset(&attr, 0, attr_sz);
 
 	attr.prog_type = prog_type;
 	attr.expected_attach_type = OPTS_GET(opts, expected_attach_type, 0);
···
 		attr.log_level = log_level;
 	}
 
-	fd = sys_bpf_prog_load(&attr, sizeof(attr), attempts);
+	fd = sys_bpf_prog_load(&attr, attr_sz, attempts);
 	if (fd >= 0)
 		return fd;
 
···
 			break;
 		}
 
-		fd = sys_bpf_prog_load(&attr, sizeof(attr), attempts);
+		fd = sys_bpf_prog_load(&attr, attr_sz, attempts);
 		if (fd >= 0)
 			goto done;
 	}
···
 		attr.log_size = log_size;
 		attr.log_level = 1;
 
-		fd = sys_bpf_prog_load(&attr, sizeof(attr), attempts);
+		fd = sys_bpf_prog_load(&attr, attr_sz, attempts);
 	}
 done:
 	/* free() doesn't affect errno, so we don't need to restore it */
···
 int bpf_map_update_elem(int fd, const void *key, const void *value,
 			__u64 flags)
 {
+	const size_t attr_sz = offsetofend(union bpf_attr, flags);
 	union bpf_attr attr;
 	int ret;
 
-	memset(&attr, 0, sizeof(attr));
+	memset(&attr, 0, attr_sz);
 	attr.map_fd = fd;
 	attr.key = ptr_to_u64(key);
 	attr.value = ptr_to_u64(value);
 	attr.flags = flags;
 
-	ret = sys_bpf(BPF_MAP_UPDATE_ELEM, &attr, sizeof(attr));
+	ret = sys_bpf(BPF_MAP_UPDATE_ELEM, &attr, attr_sz);
 	return libbpf_err_errno(ret);
 }
 
 int bpf_map_lookup_elem(int fd, const void *key, void *value)
 {
+	const size_t attr_sz = offsetofend(union bpf_attr, flags);
 	union bpf_attr attr;
 	int ret;
 
-	memset(&attr, 0, sizeof(attr));
+	memset(&attr, 0, attr_sz);
 	attr.map_fd = fd;
 	attr.key = ptr_to_u64(key);
 	attr.value = ptr_to_u64(value);
 
-	ret = sys_bpf(BPF_MAP_LOOKUP_ELEM, &attr, sizeof(attr));
+	ret = sys_bpf(BPF_MAP_LOOKUP_ELEM, &attr, attr_sz);
 	return libbpf_err_errno(ret);
 }
 
 int bpf_map_lookup_elem_flags(int fd, const void *key, void *value, __u64 flags)
 {
+	const size_t attr_sz = offsetofend(union bpf_attr, flags);
 	union bpf_attr attr;
 	int ret;
 
-	memset(&attr, 0, sizeof(attr));
+	memset(&attr, 0, attr_sz);
 	attr.map_fd = fd;
 	attr.key = ptr_to_u64(key);
 	attr.value = ptr_to_u64(value);
 	attr.flags = flags;
 
-	ret = sys_bpf(BPF_MAP_LOOKUP_ELEM, &attr, sizeof(attr));
+	ret = sys_bpf(BPF_MAP_LOOKUP_ELEM, &attr, attr_sz);
 	return libbpf_err_errno(ret);
 }
 
 int bpf_map_lookup_and_delete_elem(int fd, const void *key, void *value)
 {
+	const size_t attr_sz = offsetofend(union bpf_attr, flags);
 	union bpf_attr attr;
 	int ret;
 
-	memset(&attr, 0, sizeof(attr));
+	memset(&attr, 0, attr_sz);
 	attr.map_fd = fd;
 	attr.key = ptr_to_u64(key);
 	attr.value = ptr_to_u64(value);
 
-	ret = sys_bpf(BPF_MAP_LOOKUP_AND_DELETE_ELEM, &attr, sizeof(attr));
+	ret = sys_bpf(BPF_MAP_LOOKUP_AND_DELETE_ELEM, &attr, attr_sz);
 	return libbpf_err_errno(ret);
 }
 
 int bpf_map_lookup_and_delete_elem_flags(int fd, const void *key, void *value, __u64 flags)
 {
+	const size_t attr_sz = offsetofend(union bpf_attr, flags);
 	union bpf_attr attr;
 	int ret;
 
-	memset(&attr, 0, sizeof(attr));
+	memset(&attr, 0, attr_sz);
 	attr.map_fd = fd;
 	attr.key = ptr_to_u64(key);
 	attr.value = ptr_to_u64(value);
 	attr.flags = flags;
 
-	ret = sys_bpf(BPF_MAP_LOOKUP_AND_DELETE_ELEM, &attr, sizeof(attr));
+	ret = sys_bpf(BPF_MAP_LOOKUP_AND_DELETE_ELEM, &attr, attr_sz);
 	return libbpf_err_errno(ret);
 }
 
 int bpf_map_delete_elem(int fd, const void *key)
 {
+	const size_t attr_sz = offsetofend(union bpf_attr, flags);
 	union bpf_attr attr;
 	int ret;
 
-	memset(&attr, 0, sizeof(attr));
+	memset(&attr, 0, attr_sz);
 	attr.map_fd = fd;
 	attr.key = ptr_to_u64(key);
 
-	ret = sys_bpf(BPF_MAP_DELETE_ELEM, &attr, sizeof(attr));
+	ret = sys_bpf(BPF_MAP_DELETE_ELEM, &attr, attr_sz);
 	return libbpf_err_errno(ret);
 }
 
 int bpf_map_delete_elem_flags(int fd, const void *key, __u64 flags)
 {
+	const size_t attr_sz = offsetofend(union bpf_attr, flags);
 	union bpf_attr attr;
 	int ret;
 
-	memset(&attr, 0, sizeof(attr));
+	memset(&attr, 0, attr_sz);
 	attr.map_fd = fd;
 	attr.key = ptr_to_u64(key);
 	attr.flags = flags;
 
-	ret = sys_bpf(BPF_MAP_DELETE_ELEM, &attr, sizeof(attr));
+	ret = sys_bpf(BPF_MAP_DELETE_ELEM, &attr, attr_sz);
 	return libbpf_err_errno(ret);
 }
 
 int bpf_map_get_next_key(int fd, const void *key, void *next_key)
 {
+	const size_t attr_sz = offsetofend(union bpf_attr, next_key);
 	union bpf_attr attr;
 	int ret;
 
-	memset(&attr, 0, sizeof(attr));
+	memset(&attr, 0, attr_sz);
 	attr.map_fd = fd;
 	attr.key = ptr_to_u64(key);
 	attr.next_key = ptr_to_u64(next_key);
 
-	ret = sys_bpf(BPF_MAP_GET_NEXT_KEY, &attr, sizeof(attr));
+	ret = sys_bpf(BPF_MAP_GET_NEXT_KEY, &attr, attr_sz);
 	return libbpf_err_errno(ret);
 }
 
 int bpf_map_freeze(int fd)
 {
+	const size_t attr_sz = offsetofend(union bpf_attr, map_fd);
 	union bpf_attr attr;
 	int ret;
 
-	memset(&attr, 0, sizeof(attr));
+	memset(&attr, 0, attr_sz);
 	attr.map_fd = fd;
 
-	ret = sys_bpf(BPF_MAP_FREEZE, &attr, sizeof(attr));
+	ret = sys_bpf(BPF_MAP_FREEZE, &attr, attr_sz);
 	return libbpf_err_errno(ret);
 }
 
···
 				__u32 *count,
 				const struct bpf_map_batch_opts *opts)
 {
+	const size_t attr_sz = offsetofend(union bpf_attr, batch);
 	union bpf_attr attr;
 	int ret;
 
 	if (!OPTS_VALID(opts, bpf_map_batch_opts))
 		return libbpf_err(-EINVAL);
 
-	memset(&attr, 0, sizeof(attr));
+	memset(&attr, 0, attr_sz);
 	attr.batch.map_fd = fd;
 	attr.batch.in_batch = ptr_to_u64(in_batch);
 	attr.batch.out_batch = ptr_to_u64(out_batch);
···
 	attr.batch.elem_flags  = OPTS_GET(opts, elem_flags, 0);
 	attr.batch.flags = OPTS_GET(opts, flags, 0);
 
-	ret = sys_bpf(cmd, &attr, sizeof(attr));
+	ret = sys_bpf(cmd, &attr, attr_sz);
 	*count = attr.batch.count;
 
 	return libbpf_err_errno(ret);
···
 
 int bpf_obj_pin(int fd, const char *pathname)
 {
+	const size_t attr_sz = offsetofend(union bpf_attr, file_flags);
 	union bpf_attr attr;
 	int ret;
 
-	memset(&attr, 0, sizeof(attr));
+	memset(&attr, 0, attr_sz);
 	attr.pathname = ptr_to_u64((void *)pathname);
 	attr.bpf_fd = fd;
 
-	ret = sys_bpf(BPF_OBJ_PIN, &attr, sizeof(attr));
+	ret = sys_bpf(BPF_OBJ_PIN, &attr, attr_sz);
 	return libbpf_err_errno(ret);
 }
 
···
 
 int bpf_obj_get_opts(const char *pathname, const struct bpf_obj_get_opts *opts)
 {
+	const size_t attr_sz = offsetofend(union bpf_attr, file_flags);
 	union bpf_attr attr;
 	int fd;
 
 	if (!OPTS_VALID(opts, bpf_obj_get_opts))
 		return libbpf_err(-EINVAL);
 
-	memset(&attr, 0, sizeof(attr));
+	memset(&attr, 0, attr_sz);
 	attr.pathname = ptr_to_u64((void *)pathname);
 	attr.file_flags = OPTS_GET(opts, file_flags, 0);
 
-	fd = sys_bpf_fd(BPF_OBJ_GET, &attr, sizeof(attr));
+	fd = sys_bpf_fd(BPF_OBJ_GET, &attr, attr_sz);
 	return libbpf_err_errno(fd);
 }
 
···
 			  enum bpf_attach_type type,
 			  const struct bpf_prog_attach_opts *opts)
 {
+	const size_t attr_sz = offsetofend(union bpf_attr, replace_bpf_fd);
 	union bpf_attr attr;
 	int ret;
 
 	if (!OPTS_VALID(opts, bpf_prog_attach_opts))
 		return libbpf_err(-EINVAL);
 
-	memset(&attr, 0, sizeof(attr));
+	memset(&attr, 0, attr_sz);
 	attr.target_fd	   = target_fd;
 	attr.attach_bpf_fd = prog_fd;
 	attr.attach_type   = type;
 	attr.attach_flags  = OPTS_GET(opts, flags, 0);
 	attr.replace_bpf_fd = OPTS_GET(opts, replace_prog_fd, 0);
 
-	ret = sys_bpf(BPF_PROG_ATTACH, &attr, sizeof(attr));
+	ret = sys_bpf(BPF_PROG_ATTACH, &attr, attr_sz);
 	return libbpf_err_errno(ret);
 }
 
···
 
 int bpf_prog_detach(int target_fd, enum bpf_attach_type type)
 {
+	const size_t attr_sz = offsetofend(union bpf_attr, replace_bpf_fd);
 	union bpf_attr attr;
 	int ret;
 
-	memset(&attr, 0, sizeof(attr));
+	memset(&attr, 0, attr_sz);
 	attr.target_fd	 = target_fd;
 	attr.attach_type = type;
 
-	ret = sys_bpf(BPF_PROG_DETACH, &attr, sizeof(attr));
+	ret = sys_bpf(BPF_PROG_DETACH, &attr, attr_sz);
 	return libbpf_err_errno(ret);
 }
 
 int bpf_prog_detach2(int prog_fd, int target_fd, enum bpf_attach_type type)
 {
+	const size_t attr_sz = offsetofend(union bpf_attr, replace_bpf_fd);
 	union bpf_attr attr;
 	int ret;
 
-	memset(&attr, 0, sizeof(attr));
+	memset(&attr, 0, attr_sz);
 	attr.target_fd	 = target_fd;
 	attr.attach_bpf_fd = prog_fd;
 	attr.attach_type = type;
 
-	ret = sys_bpf(BPF_PROG_DETACH, &attr, sizeof(attr));
+	ret = sys_bpf(BPF_PROG_DETACH, &attr, attr_sz);
 	return libbpf_err_errno(ret);
 }
 
···
 		    enum bpf_attach_type attach_type,
 		    const struct bpf_link_create_opts *opts)
 {
+	const size_t attr_sz = offsetofend(union bpf_attr, link_create);
 	__u32 target_btf_id, iter_info_len;
 	union bpf_attr attr;
 	int fd, err;
···
 			return libbpf_err(-EINVAL);
 	}
 
-	memset(&attr, 0, sizeof(attr));
+	memset(&attr, 0, attr_sz);
 	attr.link_create.prog_fd = prog_fd;
 	attr.link_create.target_fd = target_fd;
 	attr.link_create.attach_type = attach_type;
···
 		break;
 	}
 proceed:
-	fd = sys_bpf_fd(BPF_LINK_CREATE, &attr, sizeof(attr));
+	fd = sys_bpf_fd(BPF_LINK_CREATE, &attr, attr_sz);
 	if (fd >= 0)
 		return fd;
 	/* we'll get EINVAL if LINK_CREATE doesn't support attaching fentry
···
 
 int bpf_link_detach(int link_fd)
 {
+	const size_t attr_sz = offsetofend(union bpf_attr, link_detach);
 	union bpf_attr attr;
 	int ret;
 
-	memset(&attr, 0, sizeof(attr));
+	memset(&attr, 0, attr_sz);
 	attr.link_detach.link_fd = link_fd;
 
-	ret = sys_bpf(BPF_LINK_DETACH, &attr, sizeof(attr));
+	ret = sys_bpf(BPF_LINK_DETACH, &attr, attr_sz);
 	return libbpf_err_errno(ret);
 }
 
 int bpf_link_update(int link_fd, int new_prog_fd,
 		    const struct bpf_link_update_opts *opts)
 {
+	const size_t attr_sz = offsetofend(union bpf_attr, link_update);
 	union bpf_attr attr;
 	int ret;
 
 	if (!OPTS_VALID(opts, bpf_link_update_opts))
 		return libbpf_err(-EINVAL);
 
-	memset(&attr, 0, sizeof(attr));
+	memset(&attr, 0, attr_sz);
 	attr.link_update.link_fd = link_fd;
 	attr.link_update.new_prog_fd = new_prog_fd;
 	attr.link_update.flags = OPTS_GET(opts, flags, 0);
 	attr.link_update.old_prog_fd = OPTS_GET(opts, old_prog_fd, 0);
 
-	ret = sys_bpf(BPF_LINK_UPDATE, &attr, sizeof(attr));
+	ret = sys_bpf(BPF_LINK_UPDATE, &attr, attr_sz);
 	return libbpf_err_errno(ret);
 }
 
 int bpf_iter_create(int link_fd)
 {
+	const size_t attr_sz = offsetofend(union bpf_attr, iter_create);
 	union bpf_attr attr;
 	int fd;
 
-	memset(&attr, 0, sizeof(attr));
+	memset(&attr, 0, attr_sz);
 	attr.iter_create.link_fd = link_fd;
 
-	fd = sys_bpf_fd(BPF_ITER_CREATE, &attr, sizeof(attr));
+	fd = sys_bpf_fd(BPF_ITER_CREATE, &attr, attr_sz);
 	return libbpf_err_errno(fd);
 }
 
···
 			enum bpf_attach_type type,
 			struct bpf_prog_query_opts *opts)
 {
+	const size_t attr_sz = offsetofend(union bpf_attr, query);
 	union bpf_attr attr;
 	int ret;
 
 	if (!OPTS_VALID(opts, bpf_prog_query_opts))
 		return libbpf_err(-EINVAL);
 
-	memset(&attr, 0, sizeof(attr));
+	memset(&attr, 0, attr_sz);
 
 	attr.query.target_fd	= target_fd;
 	attr.query.attach_type	= type;
···
 	attr.query.prog_ids	= ptr_to_u64(OPTS_GET(opts, prog_ids, NULL));
 	attr.query.prog_attach_flags = ptr_to_u64(OPTS_GET(opts, prog_attach_flags, NULL));
 
-	ret = sys_bpf(BPF_PROG_QUERY, &attr, sizeof(attr));
+	ret = sys_bpf(BPF_PROG_QUERY, &attr, attr_sz);
 
 	OPTS_SET(opts, attach_flags, attr.query.attach_flags);
 	OPTS_SET(opts, prog_cnt, attr.query.prog_cnt);
···
 
 int bpf_prog_test_run_opts(int prog_fd, struct bpf_test_run_opts *opts)
 {
+	const size_t attr_sz = offsetofend(union bpf_attr, test);
 	union bpf_attr attr;
 	int ret;
 
 	if (!OPTS_VALID(opts, bpf_test_run_opts))
 		return libbpf_err(-EINVAL);
 
-	memset(&attr, 0, sizeof(attr));
+	memset(&attr, 0, attr_sz);
 	attr.test.prog_fd = prog_fd;
 	attr.test.batch_size = OPTS_GET(opts, batch_size, 0);
 	attr.test.cpu = OPTS_GET(opts, cpu, 0);
···
 	attr.test.data_in = ptr_to_u64(OPTS_GET(opts, data_in, NULL));
 	attr.test.data_out = ptr_to_u64(OPTS_GET(opts, data_out, NULL));
 
-	ret = sys_bpf(BPF_PROG_TEST_RUN, &attr, sizeof(attr));
+	ret = sys_bpf(BPF_PROG_TEST_RUN, &attr, attr_sz);
 
 	OPTS_SET(opts, data_size_out, attr.test.data_size_out);
 	OPTS_SET(opts, ctx_size_out, attr.test.ctx_size_out);
···
 
 static int bpf_obj_get_next_id(__u32 start_id, __u32 *next_id, int cmd)
 {
+	const size_t attr_sz = offsetofend(union bpf_attr, open_flags);
 	union bpf_attr attr;
 	int err;
 
-	memset(&attr, 0, sizeof(attr));
+	memset(&attr, 0, attr_sz);
 	attr.start_id = start_id;
 
-	err = sys_bpf(cmd, &attr, sizeof(attr));
+	err = sys_bpf(cmd, &attr, attr_sz);
 	if (!err)
 		*next_id = attr.next_id;
 
···
 
 int bpf_prog_get_fd_by_id(__u32 id)
 {
+	const size_t attr_sz = offsetofend(union bpf_attr, open_flags);
 	union bpf_attr attr;
 	int fd;
 
-	memset(&attr, 0, sizeof(attr));
+	memset(&attr, 0, attr_sz);
 	attr.prog_id = id;
 
-	fd = sys_bpf_fd(BPF_PROG_GET_FD_BY_ID, &attr, sizeof(attr));
+	fd = sys_bpf_fd(BPF_PROG_GET_FD_BY_ID, &attr, attr_sz);
 	return libbpf_err_errno(fd);
 }
 
 int bpf_map_get_fd_by_id(__u32 id)
 {
+	const size_t attr_sz = offsetofend(union bpf_attr, open_flags);
 	union bpf_attr attr;
 	int fd;
 
-	memset(&attr, 0, sizeof(attr));
+	memset(&attr, 0, attr_sz);
 	attr.map_id = id;
 
-	fd = sys_bpf_fd(BPF_MAP_GET_FD_BY_ID, &attr, sizeof(attr));
+	fd = sys_bpf_fd(BPF_MAP_GET_FD_BY_ID, &attr, attr_sz);
 	return libbpf_err_errno(fd);
 }
 
 int bpf_btf_get_fd_by_id(__u32 id)
 {
+	const size_t attr_sz = offsetofend(union bpf_attr, open_flags);
 	union bpf_attr attr;
 	int fd;
 
-	memset(&attr, 0, sizeof(attr));
+	memset(&attr, 0, attr_sz);
 	attr.btf_id = id;
 
-	fd = sys_bpf_fd(BPF_BTF_GET_FD_BY_ID, &attr, sizeof(attr));
+	fd = sys_bpf_fd(BPF_BTF_GET_FD_BY_ID, &attr, attr_sz);
 	return libbpf_err_errno(fd);
 }
 
 int bpf_link_get_fd_by_id(__u32 id)
 {
+	const size_t attr_sz = offsetofend(union bpf_attr, open_flags);
 	union bpf_attr attr;
 	int fd;
 
-	memset(&attr, 0, sizeof(attr));
+	memset(&attr, 0, attr_sz);
 	attr.link_id = id;
 
-	fd = sys_bpf_fd(BPF_LINK_GET_FD_BY_ID, &attr, sizeof(attr));
+	fd = sys_bpf_fd(BPF_LINK_GET_FD_BY_ID, &attr, attr_sz);
 	return libbpf_err_errno(fd);
 }
 
 int bpf_obj_get_info_by_fd(int bpf_fd, void *info, __u32 *info_len)
 {
+	const size_t attr_sz = offsetofend(union bpf_attr, info);
 	union bpf_attr attr;
 	int err;
 
-	memset(&attr, 0, sizeof(attr));
+	memset(&attr, 0, attr_sz);
 	attr.info.bpf_fd = bpf_fd;
 	attr.info.info_len = *info_len;
 	attr.info.info = ptr_to_u64(info);
 
-	err = sys_bpf(BPF_OBJ_GET_INFO_BY_FD, &attr, sizeof(attr));
-
+	err = sys_bpf(BPF_OBJ_GET_INFO_BY_FD, &attr, attr_sz);
 	if (!err)
 		*info_len = attr.info.info_len;
-
 	return libbpf_err_errno(err);
 }
 
 int bpf_raw_tracepoint_open(const char *name, int prog_fd)
 {
+	const size_t attr_sz = offsetofend(union bpf_attr, raw_tracepoint);
 	union bpf_attr attr;
 	int fd;
 
-	memset(&attr, 0, sizeof(attr));
+	memset(&attr, 0, attr_sz);
 	attr.raw_tracepoint.name = ptr_to_u64(name);
 	attr.raw_tracepoint.prog_fd = prog_fd;
 
-	fd = sys_bpf_fd(BPF_RAW_TRACEPOINT_OPEN, &attr, sizeof(attr));
+	fd = sys_bpf_fd(BPF_RAW_TRACEPOINT_OPEN, &attr, attr_sz);
 	return libbpf_err_errno(fd);
 }
 
···
 		      __u32 *prog_id, __u32 *fd_type, __u64 *probe_offset,
 		      __u64 *probe_addr)
 {
-	union bpf_attr attr = {};
+	const size_t attr_sz = offsetofend(union bpf_attr, task_fd_query);
+	union bpf_attr attr;
 	int err;
 
+	memset(&attr, 0, attr_sz);
 	attr.task_fd_query.pid = pid;
 	attr.task_fd_query.fd = fd;
 	attr.task_fd_query.flags = flags;
 	attr.task_fd_query.buf = ptr_to_u64(buf);
 	attr.task_fd_query.buf_len = *buf_len;
 
-	err = sys_bpf(BPF_TASK_FD_QUERY, &attr, sizeof(attr));
+	err = sys_bpf(BPF_TASK_FD_QUERY, &attr, attr_sz);
 
 	*buf_len = attr.task_fd_query.buf_len;
 	*prog_id = attr.task_fd_query.prog_id;
···
 
 int bpf_enable_stats(enum bpf_stats_type type)
 {
+	const size_t attr_sz = offsetofend(union bpf_attr, enable_stats);
 	union bpf_attr attr;
 	int fd;
 
-	memset(&attr, 0, sizeof(attr));
+	memset(&attr, 0, attr_sz);
 	attr.enable_stats.type = type;
 
-	fd = sys_bpf_fd(BPF_ENABLE_STATS, &attr, sizeof(attr));
+	fd = sys_bpf_fd(BPF_ENABLE_STATS, &attr, attr_sz);
 	return libbpf_err_errno(fd);
 }
 
 int bpf_prog_bind_map(int prog_fd, int map_fd,
 		      const struct bpf_prog_bind_opts *opts)
 {
+	const size_t attr_sz = offsetofend(union bpf_attr, prog_bind_map);
 	union bpf_attr attr;
 	int ret;
 
 	if (!OPTS_VALID(opts, bpf_prog_bind_opts))
 		return libbpf_err(-EINVAL);
 
-	memset(&attr, 0, sizeof(attr));
+	memset(&attr, 0, attr_sz);
 	attr.prog_bind_map.prog_fd = prog_fd;
 	attr.prog_bind_map.map_fd = map_fd;
 	attr.prog_bind_map.flags = OPTS_GET(opts, flags, 0);
 
-	ret = sys_bpf(BPF_PROG_BIND_MAP, &attr, sizeof(attr));
+	ret = sys_bpf(BPF_PROG_BIND_MAP, &attr, attr_sz);
 	return libbpf_err_errno(ret);
 }

tools/lib/bpf/libbpf.c

···
 
 int bpf_map__reuse_fd(struct bpf_map *map, int fd)
 {
-	struct bpf_map_info info = {};
+	struct bpf_map_info info;
 	__u32 len = sizeof(info), name_len;
 	int new_fd, err;
 	char *new_name;
 
+	memset(&info, 0, len);
 	err = bpf_obj_get_info_by_fd(fd, &info, &len);
 	if (err && errno == EINVAL)
 		err = bpf_get_map_info_from_fdinfo(fd, &info);
···
 
 static bool map_is_reuse_compat(const struct bpf_map *map, int map_fd)
 {
-	struct bpf_map_info map_info = {};
+	struct bpf_map_info map_info;
 	char msg[STRERR_BUFSIZE];
-	__u32 map_info_len;
+	__u32 map_info_len = sizeof(map_info);
 	int err;
 
-	map_info_len = sizeof(map_info);
-
+	memset(&map_info, 0, map_info_len);
 	err = bpf_obj_get_info_by_fd(map_fd, &map_info, &map_info_len);
 	if (err && errno == EINVAL)
 		err = bpf_get_map_info_from_fdinfo(map_fd, &map_info);
···
 
 static int libbpf_find_prog_btf_id(const char *name, __u32 attach_prog_fd)
 {
-	struct bpf_prog_info info = {};
+	struct bpf_prog_info info;
 	__u32 info_len = sizeof(info);
 	struct btf *btf;
 	int err;
 
+	memset(&info, 0, info_len);
 	err = bpf_obj_get_info_by_fd(attach_prog_fd, &info, &info_len);
 	if (err) {
 		pr_warn("failed bpf_obj_get_info_by_fd for FD %d: %d\n",
···
 static int perf_event_open_probe(bool uprobe, bool retprobe, const char *name,
 				 uint64_t offset, int pid, size_t ref_ctr_off)
 {
-	struct perf_event_attr attr = {};
+	const size_t attr_sz = sizeof(struct perf_event_attr);
+	struct perf_event_attr attr;
 	char errmsg[STRERR_BUFSIZE];
 	int type, pfd;
 
 	if (ref_ctr_off >= (1ULL << PERF_UPROBE_REF_CTR_OFFSET_BITS))
 		return -EINVAL;
+
+	memset(&attr, 0, attr_sz);
 
 	type = uprobe ? determine_uprobe_perf_type()
 		      : determine_kprobe_perf_type();
···
 		}
 		attr.config |= 1 << bit;
 	}
-	attr.size = sizeof(attr);
+	attr.size = attr_sz;
 	attr.type = type;
 	attr.config |= (__u64)ref_ctr_off << PERF_UPROBE_REF_CTR_OFFSET_SHIFT;
 	attr.config1 = ptr_to_u64(name); /* kprobe_func or uprobe_path */
···
 static int perf_event_kprobe_open_legacy(const char *probe_name, bool retprobe,
 					 const char *kfunc_name, size_t offset, int pid)
 {
-	struct perf_event_attr attr = {};
+	const size_t attr_sz = sizeof(struct perf_event_attr);
+	struct perf_event_attr attr;
 	char errmsg[STRERR_BUFSIZE];
 	int type, pfd, err;
 
···
 			libbpf_strerror_r(err, errmsg, sizeof(errmsg)));
 		goto err_clean_legacy;
 	}
-	attr.size = sizeof(attr);
+
+	memset(&attr, 0, attr_sz);
+	attr.size = attr_sz;
 	attr.config = type;
 	attr.type = PERF_TYPE_TRACEPOINT;
 
···
 static int perf_event_uprobe_open_legacy(const char *probe_name, bool retprobe,
 					 const char *binary_path, size_t offset, int pid)
 {
+	const size_t attr_sz = sizeof(struct perf_event_attr);
 	struct perf_event_attr attr;
 	int type, pfd, err;
 
···
 		goto err_clean_legacy;
 	}
 
-	memset(&attr, 0, sizeof(attr));
-	attr.size = sizeof(attr);
+	memset(&attr, 0, attr_sz);
+	attr.size = attr_sz;
 	attr.config = type;
 	attr.type = PERF_TYPE_TRACEPOINT;
 
···
 static int perf_event_open_tracepoint(const char *tp_category,
 				      const char *tp_name)
 {
-	struct perf_event_attr attr = {};
+	const size_t attr_sz = sizeof(struct perf_event_attr);
+	struct perf_event_attr attr;
 	char errmsg[STRERR_BUFSIZE];
 	int tp_id, pfd, err;
 
···
 		return tp_id;
 	}
 
+	memset(&attr, 0, attr_sz);
 	attr.type = PERF_TYPE_TRACEPOINT;
-	attr.size = sizeof(attr);
+	attr.size = attr_sz;
 	attr.config = tp_id;
 
 	pfd = syscall(__NR_perf_event_open, &attr, -1 /* pid */, 0 /* cpu */,
···
 				     void *ctx,
 				     const struct perf_buffer_opts *opts)
 {
+	const size_t attr_sz = sizeof(struct perf_event_attr);
 	struct perf_buffer_params p = {};
-	struct perf_event_attr attr = {};
+	struct perf_event_attr attr;
 
 	if (!OPTS_VALID(opts, perf_buffer_opts))
 		return libbpf_err_ptr(-EINVAL);
 
+	memset(&attr, 0, attr_sz);
+	attr.size = attr_sz;
 	attr.config = PERF_COUNT_SW_BPF_OUTPUT;
 	attr.type = PERF_TYPE_SOFTWARE;
 	attr.sample_type = PERF_SAMPLE_RAW;

tools/lib/bpf/netlink.c

···
 
 static int tc_add_fd_and_name(struct libbpf_nla_req *req, int fd)
 {
-	struct bpf_prog_info info = {};
+	struct bpf_prog_info info;
 	__u32 info_len = sizeof(info);
 	char name[256];
 	int len, ret;
 
+	memset(&info, 0, info_len);
 	ret = bpf_obj_get_info_by_fd(fd, &info, &info_len);
 	if (ret < 0)
 		return ret;

tools/lib/bpf/skel_internal.h

···
 
 static inline int bpf_load_and_run(struct bpf_load_and_run_opts *opts)
 {
+	const size_t prog_load_attr_sz = offsetofend(union bpf_attr, fd_array);
+	const size_t test_run_attr_sz = offsetofend(union bpf_attr, test);
 	int map_fd = -1, prog_fd = -1, key = 0, err;
 	union bpf_attr attr;
 
···
 		goto out;
 	}
 
-	memset(&attr, 0, sizeof(attr));
+	memset(&attr, 0, prog_load_attr_sz);
 	attr.prog_type = BPF_PROG_TYPE_SYSCALL;
 	attr.insns = (long) opts->insns;
 	attr.insn_cnt = opts->insns_sz / sizeof(struct bpf_insn);
···
 	attr.log_size = opts->ctx->log_size;
 	attr.log_buf = opts->ctx->log_buf;
 	attr.prog_flags = BPF_F_SLEEPABLE;
-	err = prog_fd = skel_sys_bpf(BPF_PROG_LOAD, &attr, sizeof(attr));
+	err = prog_fd = skel_sys_bpf(BPF_PROG_LOAD, &attr, prog_load_attr_sz);
 	if (prog_fd < 0) {
 		opts->errstr = "failed to load loader prog";
 		set_err;
 		goto out;
 	}
 
-	memset(&attr, 0, sizeof(attr));
+	memset(&attr, 0, test_run_attr_sz);
 	attr.test.prog_fd = prog_fd;
 	attr.test.ctx_in = (long) opts->ctx;
 	attr.test.ctx_size_in = opts->ctx->sz;
-	err = skel_sys_bpf(BPF_PROG_RUN, &attr, sizeof(attr));
+	err = skel_sys_bpf(BPF_PROG_RUN, &attr, test_run_attr_sz);
 	if (err < 0 || (int)attr.test.retval < 0) {
 		opts->errstr = "failed to execute loader prog";
 		if (err < 0) {