selftests/bpf: Fix compiler warnings reported in -O2 mode

Fix a bunch of potentially unitialized variable usage warnings that are
reported by GCC in -O2 mode. Also silence overzealous stringop-truncation
class of warnings.

Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Jiri Olsa <jolsa@kernel.org>
Link: https://lore.kernel.org/bpf/20231006175744.3136675-1-andrii@kernel.org

Author: anakryiko

tools/testing/selftests/bpf/Makefile

@@ -27,7 +27,9 @@ endif
 BPF_GCC		?= $(shell command -v bpf-gcc;)
 SAN_CFLAGS	?=
 SAN_LDFLAGS	?= $(SAN_CFLAGS)
-CFLAGS += -g -O0 -rdynamic -Wall -Werror $(GENFLAGS) $(SAN_CFLAGS)	\
+CFLAGS += -g -O0 -rdynamic						\
+	  -Wall -Werror 						\
+	  $(GENFLAGS) $(SAN_CFLAGS)					\
 	  -I$(CURDIR) -I$(INCLUDE_DIR) -I$(GENDIR) -I$(LIBDIR)		\
 	  -I$(TOOLSINCDIR) -I$(APIDIR) -I$(OUTPUT)
 LDFLAGS += $(SAN_LDFLAGS)

tools/testing/selftests/bpf/map_tests/map_in_map_batch_ops.c

@@ -33,11 +33,11 @@ static void create_inner_maps(enum bpf_map_type map_type,
 {
 	int map_fd, map_index, ret;
 	__u32 map_key = 0, map_id;
-	char map_name[15];
+	char map_name[16];
 
 	for (map_index = 0; map_index < OUTER_MAP_ENTRIES; map_index++) {
 		memset(map_name, 0, sizeof(map_name));
-		sprintf(map_name, "inner_map_fd_%d", map_index);
+		snprintf(map_name, sizeof(map_name), "inner_map_fd_%d", map_index);
 		map_fd = bpf_map_create(map_type, map_name, sizeof(__u32),
 					sizeof(__u32), 1, NULL);
 		CHECK(map_fd < 0,

tools/testing/selftests/bpf/prog_tests/bloom_filter_map.c

@@ -193,8 +193,8 @@ static int setup_progs(struct bloom_filter_map **out_skel, __u32 **out_rand_vals
 
 void test_bloom_filter_map(void)
 {
-	__u32 *rand_vals, nr_rand_vals;
-	struct bloom_filter_map *skel;
+	__u32 *rand_vals = NULL, nr_rand_vals = 0;
+	struct bloom_filter_map *skel = NULL;
 	int err;
 
 	test_fail_cases();

tools/testing/selftests/bpf/prog_tests/connect_ping.c

@@ -28,9 +28,9 @@ static void subtest(int cgroup_fd, struct connect_ping *skel,
 		.sin6_family = AF_INET6,
 		.sin6_addr = IN6ADDR_LOOPBACK_INIT,
 	};
-	struct sockaddr *sa;
+	struct sockaddr *sa = NULL;
 	socklen_t sa_len;
-	int protocol;
+	int protocol = -1;
 	int sock_fd;
 
 	switch (family) {

tools/testing/selftests/bpf/prog_tests/linked_list.c

@@ -268,7 +268,7 @@ static struct btf *init_btf(void)
 
 static void list_and_rb_node_same_struct(bool refcount_field)
 {
-	int bpf_rb_node_btf_id, bpf_refcount_btf_id, foo_btf_id;
+	int bpf_rb_node_btf_id, bpf_refcount_btf_id = 0, foo_btf_id;
 	struct btf *btf;
 	int id, err;
 

tools/testing/selftests/bpf/prog_tests/lwt_helpers.h

@@ -49,7 +49,8 @@ static int open_tuntap(const char *dev_name, bool need_mac)
 		return -1;
 
 	ifr.ifr_flags = IFF_NO_PI | (need_mac ? IFF_TAP : IFF_TUN);
-	memcpy(ifr.ifr_name, dev_name, IFNAMSIZ);
+	strncpy(ifr.ifr_name, dev_name, IFNAMSIZ - 1);
+	ifr.ifr_name[IFNAMSIZ - 1] = '\0';
 
 	err = ioctl(fd, TUNSETIFF, &ifr);
 	if (!ASSERT_OK(err, "ioctl(TUNSETIFF)")) {

tools/testing/selftests/bpf/prog_tests/queue_stack_map.c

@@ -14,7 +14,7 @@ static void test_queue_stack_map_by_type(int type)
 	int i, err, prog_fd, map_in_fd, map_out_fd;
 	char file[32], buf[128];
 	struct bpf_object *obj;
-	struct iphdr iph;
+	struct iphdr iph = {};
 	LIBBPF_OPTS(bpf_test_run_opts, topts,
 		.data_in = &pkt_v4,
 		.data_size_in = sizeof(pkt_v4),

tools/testing/selftests/bpf/prog_tests/sockmap_basic.c

@@ -359,7 +359,7 @@ static void test_sockmap_progs_query(enum bpf_attach_type attach_type)
 static void test_sockmap_skb_verdict_shutdown(void)
 {
 	struct epoll_event ev, events[MAX_EVENTS];
-	int n, err, map, verdict, s, c1, p1;
+	int n, err, map, verdict, s, c1 = -1, p1 = -1;
 	struct test_sockmap_pass_prog *skel;
 	int epollfd;
 	int zero = 0;
@@ -414,9 +414,9 @@ static void test_sockmap_skb_verdict_shutdown(void)
 static void test_sockmap_skb_verdict_fionread(bool pass_prog)
 {
 	int expected, zero = 0, sent, recvd, avail;
-	int err, map, verdict, s, c0, c1, p0, p1;
-	struct test_sockmap_pass_prog *pass;
-	struct test_sockmap_drop_prog *drop;
+	int err, map, verdict, s, c0 = -1, c1 = -1, p0 = -1, p1 = -1;
+	struct test_sockmap_pass_prog *pass = NULL;
+	struct test_sockmap_drop_prog *drop = NULL;
 	char buf[256] = "0123456789";
 
 	if (pass_prog) {

tools/testing/selftests/bpf/prog_tests/sockmap_helpers.h

@@ -378,7 +378,7 @@ static inline int enable_reuseport(int s, int progfd)
 static inline int socket_loopback_reuseport(int family, int sotype, int progfd)
 {
 	struct sockaddr_storage addr;
-	socklen_t len;
+	socklen_t len = 0;
 	int err, s;
 
 	init_addr_loopback(family, &addr, &len);

tools/testing/selftests/bpf/prog_tests/sockmap_listen.c

@@ -73,7 +73,7 @@ static void test_insert_bound(struct test_sockmap_listen *skel __always_unused,
 			      int family, int sotype, int mapfd)
 {
 	struct sockaddr_storage addr;
-	socklen_t len;
+	socklen_t len = 0;
 	u32 key = 0;
 	u64 value;
 	int err, s;
@@ -871,7 +871,7 @@ static void test_msg_redir_to_listening(struct test_sockmap_listen *skel,
 
 static void redir_partial(int family, int sotype, int sock_map, int parser_map)
 {
-	int s, c0, c1, p0, p1;
+	int s, c0 = -1, c1 = -1, p0 = -1, p1 = -1;
 	int err, n, key, value;
 	char buf[] = "abc";