selftests/bpf: Replace strncpy() with strscpy()

strncpy() does not guarantee NULL-termination and is considered
deprecated [1]. Replace strncpy() calls with strscpy().

[1] https://docs.kernel.org/process/deprecated.html#strncpy-on-nul-terminated-strings

Signed-off-by: Ihor Solodrai <ihor.solodrai@linux.dev>
Link: https://lore.kernel.org/r/20260223190736.649171-4-ihor.solodrai@linux.dev
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

Author: theihor

tools/testing/selftests/bpf/network_helpers.c

@@ -581,8 +581,7 @@ int open_tuntap(const char *dev_name, bool need_mac)
 		return -1;
 
 	ifr.ifr_flags = IFF_NO_PI | (need_mac ? IFF_TAP : IFF_TUN);
-	strncpy(ifr.ifr_name, dev_name, IFNAMSIZ - 1);
-	ifr.ifr_name[IFNAMSIZ - 1] = '\0';
+	strscpy(ifr.ifr_name, dev_name);
 
 	err = ioctl(fd, TUNSETIFF, &ifr);
 	if (!ASSERT_OK(err, "ioctl(TUNSETIFF)")) {

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

@@ -346,8 +346,7 @@ static void test_task_sleepable(void)
 		close(finish_pipe[1]);
 
 		test_data = malloc(sizeof(char) * 10);
-		strncpy(test_data, "test_data", 10);
-		test_data[9] = '\0';
+		strscpy(test_data, "test_data", 10);
 
 		test_data_long = malloc(sizeof(char) * 5000);
 		for (int i = 0; i < 5000; ++i) {

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

@@ -570,7 +570,7 @@ static int create_tap(const char *ifname)
 	};
 	int fd, ret;
 
-	strncpy(ifr.ifr_name, ifname, sizeof(ifr.ifr_name));
+	strscpy(ifr.ifr_name, ifname);
 
 	fd = open("/dev/net/tun", O_RDWR);
 	if (fd < 0)
@@ -599,7 +599,7 @@ static int ifup(const char *ifname)
 	struct ifreq ifr = {};
 	int sk, ret;
 
-	strncpy(ifr.ifr_name, ifname, sizeof(ifr.ifr_name));
+	strscpy(ifr.ifr_name, ifname);
 
 	sk = socket(PF_INET, SOCK_DGRAM, 0);
 	if (sk < 0)

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

@@ -28,9 +28,9 @@ static void test_queue_stack_map_by_type(int type)
 		vals[i] = rand();
 
 	if (type == QUEUE)
-		strncpy(file, "./test_queue_map.bpf.o", sizeof(file));
+		strscpy(file, "./test_queue_map.bpf.o");
 	else if (type == STACK)
-		strncpy(file, "./test_stack_map.bpf.o", sizeof(file));
+		strscpy(file, "./test_stack_map.bpf.o");
 	else
 		return;
 

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

@@ -34,7 +34,7 @@ void test_skc_to_unix_sock(void)
 
 	memset(&sockaddr, 0, sizeof(sockaddr));
 	sockaddr.sun_family = AF_UNIX;
-	strncpy(sockaddr.sun_path, sock_path, strlen(sock_path));
+	strscpy(sockaddr.sun_path, sock_path);
 	sockaddr.sun_path[0] = '\0';
 
 	err = bind(sockfd, (struct sockaddr *)&sockaddr, sizeof(sockaddr));

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

@@ -262,7 +262,7 @@ static tld_key_t __tld_create_key(const char *name, size_t size, bool dyn_data)
 		if (!atomic_compare_exchange_strong(&tld_meta_p->cnt, &cnt, cnt + 1))
 			goto retry;
 
-		strncpy(tld_meta_p->metadata[i].name, name, TLD_NAME_LEN);
+		strscpy(tld_meta_p->metadata[i].name, name);
 		atomic_store(&tld_meta_p->metadata[i].size, size);
 		return (tld_key_t){(__s16)off};
 	}

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

@@ -1095,7 +1095,7 @@ static int tun_open(char *name)
 
 	ifr.ifr_flags = IFF_TUN | IFF_NO_PI;
 	if (*name)
-		strncpy(ifr.ifr_name, name, IFNAMSIZ);
+		strscpy(ifr.ifr_name, name);
 
 	err = ioctl(fd, TUNSETIFF, &ifr);
 	if (!ASSERT_OK(err, "ioctl TUNSETIFF"))

tools/testing/selftests/bpf/test_progs.c

@@ -1799,7 +1799,7 @@ static int worker_main_send_subtests(int sock, struct test_state *state)
 
 		msg.subtest_done.num = i;
 
-		strncpy(msg.subtest_done.name, subtest_state->name, MAX_SUBTEST_NAME);
+		strscpy(msg.subtest_done.name, subtest_state->name, MAX_SUBTEST_NAME);
 
 		msg.subtest_done.error_cnt = subtest_state->error_cnt;
 		msg.subtest_done.skipped = subtest_state->skipped;

tools/testing/selftests/bpf/xdp_hw_metadata.c

@@ -550,7 +550,7 @@ static int rxq_num(const char *ifname)
 	struct ifreq ifr = {
 		.ifr_data = (void *)&ch,
 	};
-	strncpy(ifr.ifr_name, ifname, IF_NAMESIZE - 1);
+	strscpy(ifr.ifr_name, ifname);
 	int fd, ret;
 
 	fd = socket(AF_UNIX, SOCK_DGRAM, 0);
@@ -571,7 +571,7 @@ static void hwtstamp_ioctl(int op, const char *ifname, struct hwtstamp_config *c
 	struct ifreq ifr = {
 		.ifr_data = (void *)cfg,
 	};
-	strncpy(ifr.ifr_name, ifname, IF_NAMESIZE - 1);
+	strscpy(ifr.ifr_name, ifname);
 	int fd, ret;
 
 	fd = socket(AF_UNIX, SOCK_DGRAM, 0);