tests: introduce midtail_alloc and use it in netlink tests

netlink tests happen to access memory located before the tail_malloc'ed
pointers, a practice that doesn't go well with the latest compilers
because tail_malloc is marked with ATTRIBUTE_MALLOC.
For example, glibc in -D_FORTIFY_SOURCE=2 mode and gcc 8 with
-Warray-bounds enabled complain about negative offsets out of bounds.
Fix this issue by introducing midtail_alloc.

* tests/tests.h (midtail_alloc): New macro.
* tests/netlink_crypto.c: Use it instead of tail_malloc for nlh0 allocation.
* tests/netlink_netfilter.c: Likewise.
* tests/netlink_protocol.c: Likewise.
* tests/netlink_route.c: Likewise.
* tests/netlink_selinux.c: Likewise.
* tests/netlink_sock_diag.c: Likewise.
* tests/nlattr_br_port_msg.c: Likewise.
* tests/nlattr_crypto_user_alg.c: Likewise.
* tests/nlattr_dcbmsg.c: Likewise.
* tests/nlattr_fib_rule_hdr.c: Likewise.
* tests/nlattr_ifaddrlblmsg.c: Likewise.
* tests/nlattr_ifaddrmsg.c: Likewise.
* tests/nlattr_ifinfomsg.c: Likewise.
* tests/nlattr_ifla_brport.c: Likewise.
* tests/nlattr_ifla_port.c: Likewise.
* tests/nlattr_ifla_xdp.c: Likewise.
* tests/nlattr_inet_diag_msg.c: Likewise.
* tests/nlattr_inet_diag_req_compat.c: Likewise.
* tests/nlattr_inet_diag_req_v2.c: Likewise.
* tests/nlattr_mdba_mdb_entry.c: Likewise.
* tests/nlattr_mdba_router_port.c: Likewise.
* tests/nlattr_ndmsg.c: Likewise.
* tests/nlattr_ndtmsg.c: Likewise.
* tests/nlattr_netconfmsg.c: Likewise.
* tests/nlattr_netlink_diag_msg.c: Likewise.
* tests/nlattr_nlmsgerr.c: Likewise.
* tests/nlattr_packet_diag_msg.c: Likewise.
* tests/nlattr_rtgenmsg.c: Likewise.
* tests/nlattr_rtmsg.c: Likewise.
* tests/nlattr_smc_diag_msg.c: Likewise.
* tests/nlattr_tc_stats.c: Likewise.
* tests/nlattr_tca_stab.c: Likewise.
* tests/nlattr_tcamsg.c: Likewise.
* tests/nlattr_tcmsg.c: Likewise.
* tests/nlattr_unix_diag_msg.c: Likewise.

Co-Authored-by: Dmitry V. Levin <ldv@altlinux.org>

tests/netlink_crypto.c

@@ -98,8 +98,6 @@ test_nlmsg_flags(const int fd)
 static void
 test_crypto_msg_newalg(const int fd)
 {
-	void *const nlh0 = tail_alloc(NLMSG_HDRLEN);
-
 	struct crypto_user_alg alg = {
 		.cru_name = "abcd",
 		.cru_driver_name = "efgh",
@@ -109,6 +107,8 @@ test_crypto_msg_newalg(const int fd)
 		.cru_refcnt = 0xbcacfacd,
 		.cru_flags = 0xefacdbad
 	};
+	void *const nlh0 = midtail_alloc(NLMSG_HDRLEN, sizeof(alg));
+
 	TEST_NETLINK_OBJECT_EX(fd, nlh0,
 			       CRYPTO_MSG_NEWALG, NLM_F_REQUEST,
 			       alg, print_quoted_memory,
@@ -149,7 +149,7 @@ test_crypto_msg_newalg(const int fd)
 static void
 test_crypto_msg_unspec(const int fd)
 {
-	void *const nlh0 = tail_alloc(NLMSG_HDRLEN);
+	void *const nlh0 = midtail_alloc(NLMSG_HDRLEN, 4);
 
 	TEST_NETLINK_(fd, nlh0,
 		      0xffff, "0xffff /* CRYPTO_MSG_??? */",

tests/netlink_netfilter.c

@@ -88,8 +88,8 @@ test_nlmsg_type(const int fd)
 static void
 test_nlmsg_done(const int fd)
 {
-	void *const nlh0 = tail_alloc(NLMSG_HDRLEN);
 	const int num = 0xabcdefad;
+	void *const nlh0 = midtail_alloc(NLMSG_HDRLEN, sizeof(num));
 
 	TEST_NETLINK(fd, nlh0, NLMSG_DONE, NLM_F_REQUEST,
 		     sizeof(num), &num, sizeof(num),
@@ -99,13 +99,21 @@ test_nlmsg_done(const int fd)
 static void
 test_nfgenmsg(const int fd)
 {
-	void *const nlh0 = tail_alloc(NLMSG_HDRLEN);
+	static const struct nlattr nla = {
+		.nla_len = sizeof(nla),
+		.nla_type = 0x0bcd
+	};
 
 	struct nfgenmsg msg = {
 		.nfgen_family = AF_UNIX,
 		.version = NFNETLINK_V0,
 		.res_id = NFNL_SUBSYS_NFTABLES
 	};
+	char str_buf[NLMSG_ALIGN(sizeof(msg)) + 4];
+	char nla_buf[NLMSG_ALIGN(sizeof(msg)) + sizeof(nla)];
+
+	void *const nlh0 = midtail_alloc(NLMSG_HDRLEN,
+					 MAX(sizeof(str_buf), sizeof(nla_buf)));
 
 	TEST_NETLINK_OBJECT_EX_(fd, nlh0,
 				NFNL_SUBSYS_NFTABLES << 8 | NFT_MSG_NEWTABLE,
@@ -150,8 +158,6 @@ test_nfgenmsg(const int fd)
 		     printf(", version=NFNETLINK_V0");
 		     printf(", res_id=htons(%d)", NFNL_SUBSYS_NFTABLES));
 
-	char str_buf[NLMSG_ALIGN(sizeof(msg)) + 4];
-
 	msg.res_id = htons(0xabcd);
 	memcpy(str_buf, &msg, sizeof(msg));
 	memcpy(str_buf + NLMSG_ALIGN(sizeof(msg)), "1234", 4);
@@ -165,12 +171,6 @@ test_nfgenmsg(const int fd)
 			    ", \"\\x31\\x32\\x33\\x34\"", 0xabcd));
 # endif /* NFNL_MSG_BATCH_BEGIN */
 
-	static const struct nlattr nla = {
-		.nla_len = sizeof(nla),
-		.nla_type = 0x0bcd
-	};
-	char nla_buf[NLMSG_ALIGN(sizeof(msg)) + sizeof(nla)];
-
 	msg.res_id = htons(NFNL_SUBSYS_NFTABLES);
 	memcpy(nla_buf, &msg, sizeof(msg));
 	memcpy(nla_buf + NLMSG_ALIGN(sizeof(msg)), &nla, sizeof(nla));

tests/netlink_protocol.c

@@ -203,7 +203,7 @@ test_nlmsgerr(const int fd)
 {
 	struct nlmsgerr *err;
 	struct nlmsghdr *nlh;
-	void *const nlh0 = tail_alloc(NLMSG_HDRLEN);
+	void *const nlh0 = midtail_alloc(NLMSG_HDRLEN, sizeof(*err) + 4);
 	long rc;
 
 	/* error message without enough room for the error code */
@@ -318,9 +318,9 @@ static void
 test_nlmsg_done(const int fd)
 {
 	struct nlmsghdr *nlh;
-	void *const nlh0 = tail_alloc(NLMSG_HDRLEN);
-	long rc;
 	const int num = 0xfacefeed;
+	void *const nlh0 = midtail_alloc(NLMSG_HDRLEN, sizeof(num));
+	long rc;
 
 	/* NLMSG_DONE message without enough room for an integer payload */
 	nlh = nlh0;

tests/netlink_route.c

@@ -143,8 +143,8 @@ test_nlmsg_flags(const int fd)
 static void
 test_nlmsg_done(const int fd)
 {
-	void *const nlh0 = tail_alloc(NLMSG_HDRLEN);
 	const int num = 0xabcdefad;
+	void *const nlh0 = midtail_alloc(NLMSG_HDRLEN, sizeof(num));
 
 	TEST_NETLINK(fd, nlh0, NLMSG_DONE, NLM_F_REQUEST,
 		     sizeof(num), &num, sizeof(num),
@@ -154,10 +154,11 @@ test_nlmsg_done(const int fd)
 static void
 test_rtnl_unspec(const int fd)
 {
-	void *const nlh0 = tail_alloc(NLMSG_HDRLEN);
+	uint8_t family = 0;
+	char buf[sizeof(family) + 4];
+	void *const nlh0 = midtail_alloc(NLMSG_HDRLEN, sizeof(buf));
 
 	/* unspecified family only */
-	uint8_t family = 0;
 	TEST_NETLINK_(fd, nlh0,
 		      0xffff, "0xffff /* RTM_??? */",
 		      NLM_F_REQUEST, "NLM_F_REQUEST",
@@ -180,7 +181,6 @@ test_rtnl_unspec(const int fd)
 		      printf("%p", NLMSG_DATA(TEST_NETLINK_nlh)));
 
 	/* unspecified family and string */
-	char buf[sizeof(family) + 4];
 	family = 0;
 	memcpy(buf, &family, sizeof(family));
 	memcpy(buf + sizeof(family), "1234", 4);
@@ -204,7 +204,6 @@ test_rtnl_unspec(const int fd)
 static void
 test_rtnl_link(const int fd)
 {
-	void *const nlh0 = tail_alloc(NLMSG_HDRLEN);
 	const struct ifinfomsg ifinfo = {
 		.ifi_family = AF_UNIX,
 		.ifi_type = ARPHRD_LOOPBACK,
@@ -212,6 +211,7 @@ test_rtnl_link(const int fd)
 		.ifi_flags = IFF_UP,
 		.ifi_change = 0xfabcdeba
 	};
+	void *const nlh0 = midtail_alloc(NLMSG_HDRLEN, sizeof(ifinfo));
 
 	TEST_NL_ROUTE(fd, nlh0, RTM_GETLINK, ifinfo,
 		      printf("{ifi_family=AF_UNIX"),
@@ -225,7 +225,6 @@ test_rtnl_link(const int fd)
 static void
 test_rtnl_addr(const int fd)
 {
-	void *const nlh0 = tail_alloc(NLMSG_HDRLEN);
 	const struct ifaddrmsg msg = {
 		.ifa_family = AF_UNIX,
 		.ifa_prefixlen = 0xde,
@@ -233,6 +232,7 @@ test_rtnl_addr(const int fd)
 		.ifa_scope = RT_SCOPE_UNIVERSE,
 		.ifa_index = ifindex_lo()
 	};
+	void *const nlh0 = midtail_alloc(NLMSG_HDRLEN, sizeof(msg));
 
 	TEST_NL_ROUTE(fd, nlh0, RTM_GETADDR, msg,
 		      printf("{ifa_family=AF_UNIX"),
@@ -246,7 +246,6 @@ test_rtnl_addr(const int fd)
 static void
 test_rtnl_route(const int fd)
 {
-	void *const nlh0 = tail_alloc(NLMSG_HDRLEN);
 	static const struct rtmsg msg = {
 		.rtm_family = AF_UNIX,
 		.rtm_dst_len = 0xaf,
@@ -258,6 +257,7 @@ test_rtnl_route(const int fd)
 		.rtm_type = RTN_LOCAL,
 		.rtm_flags = RTM_F_NOTIFY
 	};
+	void *const nlh0 = midtail_alloc(NLMSG_HDRLEN, sizeof(msg));
 
 	TEST_NL_ROUTE(fd, nlh0, RTM_GETROUTE, msg,
 		      printf("{rtm_family=AF_UNIX"),
@@ -275,7 +275,6 @@ test_rtnl_route(const int fd)
 static void
 test_rtnl_rule(const int fd)
 {
-	void *const nlh0 = tail_alloc(NLMSG_HDRLEN);
 	struct rtmsg msg = {
 		.rtm_family = AF_UNIX,
 		.rtm_dst_len = 0xaf,
@@ -285,6 +284,7 @@ test_rtnl_rule(const int fd)
 		.rtm_type = FR_ACT_TO_TBL,
 		.rtm_flags = FIB_RULE_INVERT
 	};
+	void *const nlh0 = midtail_alloc(NLMSG_HDRLEN, sizeof(msg));
 
 	TEST_NL_ROUTE(fd, nlh0, RTM_GETRULE, msg,
 		      printf("{family=AF_UNIX"),
@@ -301,7 +301,6 @@ test_rtnl_rule(const int fd)
 static void
 test_rtnl_neigh(const int fd)
 {
-	void *const nlh0 = tail_alloc(NLMSG_HDRLEN);
 	const struct ndmsg msg = {
 		.ndm_family = AF_UNIX,
 		.ndm_ifindex = ifindex_lo(),
@@ -309,6 +308,7 @@ test_rtnl_neigh(const int fd)
 		.ndm_flags = NTF_PROXY,
 		.ndm_type = RTN_UNSPEC
 	};
+	void *const nlh0 = midtail_alloc(NLMSG_HDRLEN, sizeof(msg));
 
 	TEST_NL_ROUTE(fd, nlh0, RTM_GETNEIGH, msg,
 		      printf("{ndm_family=AF_UNIX"),
@@ -321,10 +321,10 @@ test_rtnl_neigh(const int fd)
 static void
 test_rtnl_neightbl(const int fd)
 {
-	void *const nlh0 = tail_alloc(NLMSG_HDRLEN);
 	static const struct ndtmsg msg = {
 		.ndtm_family = AF_NETLINK
 	};
+	void *const nlh0 = midtail_alloc(NLMSG_HDRLEN, sizeof(msg));
 
 	TEST_NETLINK(fd, nlh0,
 		     RTM_GETNEIGHTBL, NLM_F_REQUEST,
@@ -335,7 +335,6 @@ test_rtnl_neightbl(const int fd)
 static void
 test_rtnl_tc(const int fd)
 {
-	void *const nlh0 = tail_alloc(NLMSG_HDRLEN);
 	const struct tcmsg msg = {
 		.tcm_family = AF_UNIX,
 		.tcm_ifindex = ifindex_lo(),
@@ -343,6 +342,7 @@ test_rtnl_tc(const int fd)
 		.tcm_parent = 0xafbcadab,
 		.tcm_info = 0xbcaedafa
 	};
+	void *const nlh0 = midtail_alloc(NLMSG_HDRLEN, sizeof(msg));
 
 	TEST_NL_ROUTE(fd, nlh0, RTM_GETQDISC, msg,
 		      printf("{tcm_family=AF_UNIX"),
@@ -356,10 +356,10 @@ test_rtnl_tc(const int fd)
 static void
 test_rtnl_tca(const int fd)
 {
-	void *const nlh0 = tail_alloc(NLMSG_HDRLEN);
 	struct tcamsg msg = {
 		.tca_family = AF_INET
 	};
+	void *const nlh0 = midtail_alloc(NLMSG_HDRLEN, sizeof(msg));
 
 	TEST_NETLINK(fd, nlh0,
 		     RTM_GETACTION, NLM_F_REQUEST,
@@ -371,7 +371,6 @@ test_rtnl_tca(const int fd)
 static void
 test_rtnl_addrlabel(const int fd)
 {
-	void *const nlh0 = tail_alloc(NLMSG_HDRLEN);
 	const struct ifaddrlblmsg msg = {
 		.ifal_family = AF_UNIX,
 		.ifal_prefixlen = 0xaf,
@@ -379,6 +378,7 @@ test_rtnl_addrlabel(const int fd)
 		.ifal_index = ifindex_lo(),
 		.ifal_seq = 0xfadcdafb
 	};
+	void *const nlh0 = midtail_alloc(NLMSG_HDRLEN, sizeof(msg));
 
 	TEST_NL_ROUTE(fd, nlh0, RTM_GETADDRLABEL, msg,
 		      printf("{ifal_family=AF_UNIX"),
@@ -394,11 +394,11 @@ test_rtnl_addrlabel(const int fd)
 static void
 test_rtnl_dcb(const int fd)
 {
-	void *const nlh0 = tail_alloc(NLMSG_HDRLEN);
 	static const struct dcbmsg msg = {
 		.dcb_family = AF_UNIX,
 		.cmd = DCB_CMD_UNDEFINED
 	};
+	void *const nlh0 = midtail_alloc(NLMSG_HDRLEN, sizeof(msg));
 
 	TEST_NL_ROUTE(fd, nlh0, RTM_GETDCB, msg,
 		      printf("{dcb_family=AF_UNIX"),
@@ -410,10 +410,10 @@ test_rtnl_dcb(const int fd)
 static void
 test_rtnl_netconf(const int fd)
 {
-	void *const nlh0 = tail_alloc(NLMSG_HDRLEN);
 	static const struct netconfmsg msg = {
 		.ncm_family = AF_INET
 	};
+	void *const nlh0 = midtail_alloc(NLMSG_HDRLEN, sizeof(msg));
 
 	TEST_NETLINK(fd, nlh0,
 		     RTM_GETNETCONF, NLM_F_REQUEST,
@@ -426,11 +426,11 @@ test_rtnl_netconf(const int fd)
 static void
 test_rtnl_mdb(const int fd)
 {
-	void *const nlh0 = tail_alloc(NLMSG_HDRLEN);
 	const struct br_port_msg msg = {
 		.family = AF_UNIX,
 		.ifindex = ifindex_lo()
 	};
+	void *const nlh0 = midtail_alloc(NLMSG_HDRLEN, sizeof(msg));
 
 	TEST_NL_ROUTE(fd, nlh0, RTM_GETMDB, msg,
 		      printf("{family=AF_UNIX"),
@@ -442,10 +442,10 @@ test_rtnl_mdb(const int fd)
 static void
 test_rtnl_nsid(const int fd)
 {
-	void *const nlh0 = tail_alloc(NLMSG_HDRLEN);
 	static const struct rtgenmsg msg = {
 		.rtgen_family = AF_UNIX
 	};
+	void *const nlh0 = midtail_alloc(NLMSG_HDRLEN, sizeof(msg));
 
 	TEST_NETLINK(fd, nlh0,
 		     RTM_GETNSID, NLM_F_REQUEST,

tests/netlink_selinux.c

@@ -53,7 +53,7 @@ test_nlmsg_type(const int fd)
 static void
 test_selnl_msg_unspec(const int fd)
 {
-	void *const nlh0 = tail_alloc(NLMSG_HDRLEN);
+	void *const nlh0 = midtail_alloc(NLMSG_HDRLEN, 4);
 
 	TEST_NETLINK_(fd, nlh0,
 		      0xffff, "0xffff /* SELNL_MSG_??? */",
@@ -65,11 +65,11 @@ test_selnl_msg_unspec(const int fd)
 static void
 test_selnl_msg_setenforce(const int fd)
 {
-	void *const nlh0 = tail_alloc(NLMSG_HDRLEN);
-
 	static const struct selnl_msg_setenforce msg = {
 		.val = 0xfbdcdfab
 	};
+	void *const nlh0 = midtail_alloc(NLMSG_HDRLEN, sizeof(msg));
+
 	TEST_NETLINK_OBJECT(fd, nlh0,
 			    SELNL_MSG_SETENFORCE, NLM_F_REQUEST, msg,
 			    PRINT_FIELD_D("{", msg, val);
@@ -79,11 +79,11 @@ test_selnl_msg_setenforce(const int fd)
 static void
 test_selnl_msg_policyload(const int fd)
 {
-	void *const nlh0 = tail_alloc(NLMSG_HDRLEN);
-
 	static const struct selnl_msg_policyload msg = {
 		.seqno = 0xabdcfabc
 	};
+	void *const nlh0 = midtail_alloc(NLMSG_HDRLEN, sizeof(msg));
+
 	TEST_NETLINK_OBJECT(fd, nlh0,
 			    SELNL_MSG_POLICYLOAD, NLM_F_REQUEST, msg,
 			    PRINT_FIELD_U("{", msg, seqno);

tests/netlink_sock_diag.c

@@ -127,10 +127,11 @@ test_nlmsg_flags(const int fd)
 static void
 test_odd_family_req(const int fd)
 {
-	void *const nlh0 = tail_alloc(NLMSG_HDRLEN);
+	uint8_t family = 0;
+	char buf[sizeof(family) + 4];
+	void *const nlh0 = midtail_alloc(NLMSG_HDRLEN, sizeof(buf));
 
 	/* unspecified family only */
-	uint8_t family = 0;
 	TEST_NETLINK(fd, nlh0,
 		     SOCK_DIAG_BY_FAMILY,
 		     NLM_F_REQUEST,
@@ -153,7 +154,6 @@ test_odd_family_req(const int fd)
 		     printf("%p", NLMSG_DATA(TEST_NETLINK_nlh)));
 
 	/* unspecified family and string */
-	char buf[sizeof(family) + 4];
 	family = 0;
 	memcpy(buf, &family, sizeof(family));
 	memcpy(buf + sizeof(family), "1234", 4);
@@ -177,10 +177,11 @@ test_odd_family_req(const int fd)
 static void
 test_odd_family_msg(const int fd)
 {
-	void *const nlh0 = tail_alloc(NLMSG_HDRLEN);
+	uint8_t family = 0;
+	char buf[sizeof(family) + 4];
+	void *const nlh0 = midtail_alloc(NLMSG_HDRLEN, sizeof(buf));
 
 	/* unspecified family only */
-	uint8_t family = 0;
 	TEST_NETLINK(fd, nlh0,
 		     SOCK_DIAG_BY_FAMILY, NLM_F_DUMP,
 		     sizeof(family), &family, sizeof(family),
@@ -200,7 +201,6 @@ test_odd_family_msg(const int fd)
 		     printf("%p", NLMSG_DATA(TEST_NETLINK_nlh)));
 
 	/* unspecified family and string */
-	char buf[sizeof(family) + 4];
 	family = 0;
 	memcpy(buf, &family, sizeof(family));
 	memcpy(buf + sizeof(family), "1234", 4);
@@ -222,7 +222,6 @@ test_odd_family_msg(const int fd)
 static void
 test_unix_diag_req(const int fd)
 {
-	void *const nlh0 = tail_alloc(NLMSG_HDRLEN);
 	static const struct unix_diag_req req = {
 		.sdiag_family = AF_UNIX,
 		.sdiag_protocol = 253,
@@ -231,6 +230,7 @@ test_unix_diag_req(const int fd)
 		.udiag_show = UDIAG_SHOW_NAME,
 		.udiag_cookie = { 0xdeadbeef, 0xbadc0ded }
 	};
+	void *const nlh0 = midtail_alloc(NLMSG_HDRLEN, sizeof(req));
 	TEST_SOCK_DIAG(fd, nlh0, AF_UNIX,
 		       SOCK_DIAG_BY_FAMILY, NLM_F_REQUEST, req,
 		       printf("{sdiag_family=AF_UNIX"),
@@ -245,7 +245,6 @@ test_unix_diag_req(const int fd)
 static void
 test_unix_diag_msg(const int fd)
 {
-	void *const nlh0 = tail_alloc(NLMSG_HDRLEN);
 	static const struct unix_diag_msg msg = {
 		.udiag_family = AF_UNIX,
 		.udiag_type = SOCK_STREAM,
@@ -253,6 +252,7 @@ test_unix_diag_msg(const int fd)
 		.udiag_ino = 0xfacefeed,
 		.udiag_cookie = { 0xdeadbeef, 0xbadc0ded }
 	};
+	void *const nlh0 = midtail_alloc(NLMSG_HDRLEN, sizeof(msg));
 	TEST_SOCK_DIAG(fd, nlh0, AF_UNIX,
 		       SOCK_DIAG_BY_FAMILY, NLM_F_DUMP, msg,
 		       printf("{udiag_family=AF_UNIX"),
@@ -266,7 +266,6 @@ test_unix_diag_msg(const int fd)
 static void
 test_netlink_diag_req(const int fd)
 {
-	void *const nlh0 = tail_alloc(NLMSG_HDRLEN);
 	struct netlink_diag_req req = {
 		.sdiag_family = AF_NETLINK,
 		.sdiag_protocol = NDIAG_PROTO_ALL,
@@ -274,6 +273,7 @@ test_netlink_diag_req(const int fd)
 		.ndiag_show = NDIAG_SHOW_MEMINFO,
 		.ndiag_cookie = { 0xdeadbeef, 0xbadc0ded }
 	};
+	void *const nlh0 = midtail_alloc(NLMSG_HDRLEN, sizeof(req));
 	TEST_SOCK_DIAG(fd, nlh0, AF_NETLINK,
 		       SOCK_DIAG_BY_FAMILY, NLM_F_REQUEST, req,
 		       printf("{sdiag_family=AF_NETLINK"),
@@ -298,7 +298,6 @@ test_netlink_diag_req(const int fd)
 static void
 test_netlink_diag_msg(const int fd)
 {
-	void *const nlh0 = tail_alloc(NLMSG_HDRLEN);
 	static const struct netlink_diag_msg msg = {
 		.ndiag_family = AF_NETLINK,
 		.ndiag_type = SOCK_RAW,
@@ -310,6 +309,7 @@ test_netlink_diag_msg(const int fd)
 		.ndiag_ino = 0xdaeefacd,
 		.ndiag_cookie = { 0xbadc0ded, 0xdeadbeef }
 	};
+	void *const nlh0 = midtail_alloc(NLMSG_HDRLEN, sizeof(msg));
 	TEST_SOCK_DIAG(fd, nlh0, AF_NETLINK,
 		       SOCK_DIAG_BY_FAMILY, NLM_F_DUMP, msg,
 		       printf("{ndiag_family=AF_NETLINK"),
@@ -327,7 +327,6 @@ test_netlink_diag_msg(const int fd)
 static void
 test_packet_diag_req(const int fd)
 {
-	void *const nlh0 = tail_alloc(NLMSG_HDRLEN);
 	static const struct packet_diag_req req = {
 		.sdiag_family = AF_PACKET,
 		.sdiag_protocol = ETH_P_LOOP,
@@ -335,6 +334,7 @@ test_packet_diag_req(const int fd)
 		.pdiag_show = PACKET_SHOW_INFO,
 		.pdiag_cookie = { 0xdeadbeef, 0xbadc0ded }
 	};
+	void *const nlh0 = midtail_alloc(NLMSG_HDRLEN, sizeof(req));
 	TEST_SOCK_DIAG(fd, nlh0, AF_PACKET,
 		       SOCK_DIAG_BY_FAMILY, NLM_F_REQUEST, req,
 		       printf("{sdiag_family=AF_PACKET"),
@@ -348,7 +348,6 @@ test_packet_diag_req(const int fd)
 static void
 test_packet_diag_msg(const int fd)
 {
-	void *const nlh0 = tail_alloc(NLMSG_HDRLEN);
 	static const struct packet_diag_msg msg = {
 		.pdiag_family = AF_PACKET,
 		.pdiag_type = SOCK_STREAM,
@@ -356,6 +355,7 @@ test_packet_diag_msg(const int fd)
 		.pdiag_ino = 0xfacefeed,
 		.pdiag_cookie = { 0xdeadbeef, 0xbadc0ded }
 	};
+	void *const nlh0 = midtail_alloc(NLMSG_HDRLEN, sizeof(msg));
 	TEST_SOCK_DIAG(fd, nlh0, AF_PACKET,
 		       SOCK_DIAG_BY_FAMILY, NLM_F_DUMP, msg,
 		       printf("{pdiag_family=AF_PACKET"),
@@ -371,7 +371,6 @@ test_inet_diag_sockid(const int fd)
 {
 	const char address[] = "12.34.56.78";
 	const char address6[] = "12:34:56:78:90:ab:cd:ef";
-	void *const nlh0 = tail_alloc(NLMSG_HDRLEN);
 	struct inet_diag_req_v2 req = {
 		.sdiag_family = AF_INET,
 		.idiag_ext = 1 << (INET_DIAG_CONG - 1),
@@ -384,6 +383,7 @@ test_inet_diag_sockid(const int fd)
 			.idiag_cookie = { 0xdeadbeef, 0xbadc0ded }
 		},
 	};
+	void *const nlh0 = midtail_alloc(NLMSG_HDRLEN, sizeof(req));
 
 	if (!inet_pton(AF_INET, address, &req.id.idiag_src) ||
 	    !inet_pton(AF_INET, address, &req.id.idiag_dst))
@@ -435,7 +435,6 @@ static void
 test_inet_diag_req(const int fd)
 {
 	const char address[] = "12.34.56.78";
-	void *const nlh0 = tail_alloc(NLMSG_HDRLEN);
 	struct inet_diag_req req = {
 		.idiag_family = AF_INET,
 		.idiag_src_len = 0xde,
@@ -450,6 +449,7 @@ test_inet_diag_req(const int fd)
 		.idiag_states = 1 << TCP_LAST_ACK,
 		.idiag_dbs = 0xfacefeed,
 	};
+	void *const nlh0 = midtail_alloc(NLMSG_HDRLEN, sizeof(req));
 
 	if (!inet_pton(AF_INET, address, &req.id.idiag_src) ||
 	    !inet_pton(AF_INET, address, &req.id.idiag_dst))
@@ -479,7 +479,6 @@ static void
 test_inet_diag_req_v2(const int fd)
 {
 	const char address[] = "87.65.43.21";
-	void *const nlh0 = tail_alloc(NLMSG_HDRLEN);
 	struct inet_diag_req_v2 req = {
 		.sdiag_family = AF_INET,
 		.idiag_ext = 1 << (INET_DIAG_CONG - 1),
@@ -492,6 +491,7 @@ test_inet_diag_req_v2(const int fd)
 			.idiag_cookie = { 0xdeadbeef, 0xbadc0ded }
 		},
 	};
+	void *const nlh0 = midtail_alloc(NLMSG_HDRLEN, sizeof(req));
 
 	if (!inet_pton(AF_INET, address, &req.id.idiag_src) ||
 	    !inet_pton(AF_INET, address, &req.id.idiag_dst))
@@ -519,7 +519,6 @@ static void
 test_inet_diag_msg(const int fd)
 {
 	const char address[] = "11.22.33.44";
-	void *const nlh0 = tail_alloc(NLMSG_HDRLEN);
 	struct inet_diag_msg msg = {
 		.idiag_family = AF_INET,
 		.idiag_state = TCP_LISTEN,
@@ -537,6 +536,7 @@ test_inet_diag_msg(const int fd)
 		.idiag_uid = 0xdecefaeb,
 		.idiag_inode = 0xbadc0ded,
 	};
+	void *const nlh0 = midtail_alloc(NLMSG_HDRLEN, sizeof(msg));
 
 	if (!inet_pton(AF_INET, address, &msg.id.idiag_src) ||
 	    !inet_pton(AF_INET, address, &msg.id.idiag_dst))
@@ -570,7 +570,6 @@ static void
 test_smc_diag_req(const int fd)
 {
 	const char address[] = "43.21.56.78";
-	void *const nlh0 = tail_alloc(NLMSG_HDRLEN);
 	struct smc_diag_req req = {
 		.diag_family = AF_SMC,
 		.diag_ext = 1 << (SMC_DIAG_CONNINFO - 1),
@@ -581,6 +580,7 @@ test_smc_diag_req(const int fd)
 			.idiag_cookie = { 0xdeadbeef, 0xbadc0ded },
 		},
 	};
+	void *const nlh0 = midtail_alloc(NLMSG_HDRLEN, sizeof(req));
 
 	if (!inet_pton(AF_INET, address, &req.id.idiag_src) ||
 	    !inet_pton(AF_INET, address, &req.id.idiag_dst))
@@ -606,7 +606,6 @@ static void
 test_smc_diag_msg(const int fd)
 {
 	const char address[] = "34.87.12.90";
-	void *const nlh0 = tail_alloc(NLMSG_HDRLEN);
 	struct smc_diag_msg msg = {
 		.diag_family = AF_SMC,
 		.diag_state = SMC_ACTIVE,
@@ -621,6 +620,7 @@ test_smc_diag_msg(const int fd)
 		.diag_uid = 0xadcdfafc,
 		.diag_inode = 0xbadc0ded,
 	};
+	void *const nlh0 = midtail_alloc(NLMSG_HDRLEN, sizeof(msg));
 
 	if (!inet_pton(AF_INET, address, &msg.id.idiag_src) ||
 	    !inet_pton(AF_INET, address, &msg.id.idiag_dst))

tests/nlattr_br_port_msg.c

@@ -69,7 +69,7 @@ main(void)
 	const int fd = create_nl_socket(NETLINK_ROUTE);
 
 	const unsigned int hdrlen = sizeof(struct br_port_msg);
-	void *nlh0 = tail_alloc(NLMSG_SPACE(hdrlen));
+	void *nlh0 = midtail_alloc(NLMSG_SPACE(hdrlen), NLA_HDRLEN + 4);
 
 	static char pattern[4096];
 	fill_memory_ex(pattern, sizeof(pattern), 'a', 'z' - 'a' + 1);

tests/nlattr_crypto_user_alg.c

@@ -72,7 +72,12 @@ main(void)
 
 	const int fd = create_nl_socket(NETLINK_CRYPTO);
 	const unsigned int hdrlen = sizeof(struct crypto_user_alg);
-	void *const nlh0 = tail_alloc(NLMSG_SPACE(hdrlen));
+	/*
+	 * There are also other structures, but they are not bigger than
+	 * DEFAULT_STRLEN so far.
+	 */
+	void *const nlh0 = midtail_alloc(NLMSG_SPACE(hdrlen),
+					 NLA_HDRLEN + DEFAULT_STRLEN);
 
 	static char pattern[4096];
 	fill_memory_ex(pattern, sizeof(pattern), 'a', 'z' - 'a' + 1);

tests/nlattr_dcbmsg.c

@@ -67,7 +67,7 @@ main(void)
 
 	const int fd = create_nl_socket(NETLINK_ROUTE);
 	const unsigned int hdrlen = sizeof(struct dcbmsg);
-	void *nlh0 = tail_alloc(NLMSG_SPACE(hdrlen));
+	void *nlh0 = midtail_alloc(NLMSG_SPACE(hdrlen), NLA_HDRLEN + 4);
 
 	static char pattern[4096];
 	fill_memory_ex(pattern, sizeof(pattern), 'a', 'z' - 'a' + 1);

tests/nlattr_fib_rule_hdr.c

@@ -80,7 +80,7 @@ main(void)
 
 	const int fd = create_nl_socket(NETLINK_ROUTE);
 	const unsigned int hdrlen = sizeof(struct rtmsg);
-	void *nlh0 = tail_alloc(NLMSG_SPACE(hdrlen));
+	void *nlh0 = midtail_alloc(NLMSG_SPACE(hdrlen), NLA_HDRLEN + 8);
 
 	static char pattern[4096];
 	fill_memory_ex(pattern, sizeof(pattern), 'a', 'z' - 'a' + 1);

tests/nlattr_ifaddrlblmsg.c

@@ -69,7 +69,7 @@ main(void)
 
 	const int fd = create_nl_socket(NETLINK_ROUTE);
 	const unsigned int hdrlen = sizeof(struct ifaddrlblmsg);
-	void *nlh0 = tail_alloc(NLMSG_SPACE(hdrlen));
+	void *nlh0 = midtail_alloc(NLMSG_SPACE(hdrlen), NLA_HDRLEN + 4);
 
 	static char pattern[4096];
 	fill_memory_ex(pattern, sizeof(pattern), 'a', 'z' - 'a' + 1);

tests/nlattr_ifaddrmsg.c

@@ -83,9 +83,23 @@ main(void)
 {
 	skip_if_unavailable("/proc/self/fd/");
 
+	static const char address4[] = "12.34.56.78";
+	static const char address6[] = "12:34:56:78:90:ab:cd:ef";
+	static const struct ifa_cacheinfo ci = {
+		.ifa_prefered = 0xabcdefac,
+		.ifa_valid = 0xbcdadbca,
+		.cstamp = 0xcdabedba,
+		.tstamp = 0xdebabdac
+	};
+
+	struct in_addr a4;
+	struct in6_addr a6;
+	const uint32_t ifa_flags = IFA_F_SECONDARY | IFA_F_PERMANENT;
+
 	const int fd = create_nl_socket(NETLINK_ROUTE);
 	const unsigned int hdrlen = sizeof(struct ifaddrmsg);
-	void *nlh0 = tail_alloc(NLMSG_SPACE(hdrlen));
+	void *nlh0 = midtail_alloc(NLMSG_SPACE(hdrlen),
+				   NLA_HDRLEN + MAX(sizeof(ci), sizeof(a6)));
 
 	static char pattern[4096];
 	fill_memory_ex(pattern, sizeof(pattern), 'a', 'z' - 'a' + 1);
@@ -106,8 +120,6 @@ main(void)
 		    print_quoted_hex(pattern, 4));
 
 	SET_IFA_FAMILY(AF_INET);
-	static const char address4[] = "12.34.56.78";
-	struct in_addr a4;
 
 	if (!inet_pton(AF_INET, address4, &a4))
 		perror_msg_and_skip("inet_pton");
@@ -118,8 +130,6 @@ main(void)
 			   printf("%s", address4));
 
 	SET_IFA_FAMILY(AF_INET6);
-	static const char address6[] = "12:34:56:78:90:ab:cd:ef";
-	struct in6_addr a6;
 
 	if (!inet_pton(AF_INET6, address6, &a6))
 		perror_msg_and_skip("inet_pton");
@@ -129,12 +139,6 @@ main(void)
 			   IFA_ADDRESS, pattern, a6,
 			   printf("%s", address6));
 
-	static const struct ifa_cacheinfo ci = {
-		.ifa_prefered = 0xabcdefac,
-		.ifa_valid = 0xbcdadbca,
-		.cstamp = 0xcdabedba,
-		.tstamp = 0xdebabdac
-	};
 	TEST_NLATTR_OBJECT(fd, nlh0, hdrlen,
 			   init_ifaddrmsg, print_ifaddrmsg,
 			   IFA_CACHEINFO, pattern, ci,
@@ -144,7 +148,6 @@ main(void)
 			   PRINT_FIELD_U(", ", ci, tstamp);
 			   printf("}"));
 
-	const uint32_t ifa_flags = IFA_F_SECONDARY | IFA_F_PERMANENT;
 	TEST_NLATTR_OBJECT(fd, nlh0, hdrlen,
 			   init_ifaddrmsg, print_ifaddrmsg,
 			   IFA_FLAGS, pattern, ifa_flags,

tests/nlattr_ifinfomsg.c

@@ -89,28 +89,6 @@ main(void)
 {
 	skip_if_unavailable("/proc/self/fd/");
 
-	const int fd = create_nl_socket(NETLINK_ROUTE);
-	const unsigned int hdrlen = sizeof(struct ifinfomsg);
-	void *nlh0 = tail_alloc(NLMSG_SPACE(hdrlen));
-
-	static char pattern[4096];
-	fill_memory_ex(pattern, sizeof(pattern), 'a', 'z' - 'a' + 1);
-
-	const unsigned int nla_type = 0xffff & NLA_TYPE_MASK;
-	char nla_type_str[256];
-	sprintf(nla_type_str, "%#x /* IFLA_??? */", nla_type);
-	TEST_NLATTR_(fd, nlh0, hdrlen,
-		     init_ifinfomsg, print_ifinfomsg,
-		     nla_type, nla_type_str,
-		     4, pattern, 4,
-		     print_quoted_hex(pattern, 4));
-
-	const int32_t netnsid = 0xacbdabda;
-	TEST_NLATTR_OBJECT(fd, nlh0, hdrlen,
-			   init_ifinfomsg, print_ifinfomsg,
-			   IFLA_LINK_NETNSID, pattern, netnsid,
-			   printf("%d", netnsid));
-
 	static const struct rtnl_link_stats st = {
 		.rx_packets = 0xabcdefac,
 		.tx_packets = 0xbcdacdab,
@@ -136,6 +114,29 @@ main(void)
 		.rx_compressed = 0xdeffadbd,
 		.tx_compressed = 0xefdadfab
 	};
+	const int fd = create_nl_socket(NETLINK_ROUTE);
+	const unsigned int hdrlen = sizeof(struct ifinfomsg);
+	void *nlh0 = midtail_alloc(NLMSG_SPACE(hdrlen),
+				   NLA_HDRLEN + sizeof(st));
+
+	static char pattern[4096];
+	fill_memory_ex(pattern, sizeof(pattern), 'a', 'z' - 'a' + 1);
+
+	const unsigned int nla_type = 0xffff & NLA_TYPE_MASK;
+	char nla_type_str[256];
+	sprintf(nla_type_str, "%#x /* IFLA_??? */", nla_type);
+	TEST_NLATTR_(fd, nlh0, hdrlen,
+		     init_ifinfomsg, print_ifinfomsg,
+		     nla_type, nla_type_str,
+		     4, pattern, 4,
+		     print_quoted_hex(pattern, 4));
+
+	const int32_t netnsid = 0xacbdabda;
+	TEST_NLATTR_OBJECT(fd, nlh0, hdrlen,
+			   init_ifinfomsg, print_ifinfomsg,
+			   IFLA_LINK_NETNSID, pattern, netnsid,
+			   printf("%d", netnsid));
+
 	TEST_NLATTR_OBJECT(fd, nlh0, hdrlen,
 			   init_ifinfomsg, print_ifinfomsg,
 			   IFLA_STATS, pattern, st,

tests/nlattr_ifla_brport.c

@@ -84,19 +84,20 @@ main(void)
 {
 	skip_if_unavailable("/proc/self/fd/");
 
+	const uint16_t u16 = 0xabcd;
+	const uint64_t u64 = 0xabcdedeeefeafeab;
 	const int fd = create_nl_socket(NETLINK_ROUTE);
-	void *nlh0 = tail_alloc(NLMSG_SPACE(hdrlen));
+	void *nlh0 = midtail_alloc(NLMSG_SPACE(hdrlen),
+				   NLA_HDRLEN * 2 + sizeof(u64));
 
 	static char pattern[4096];
 	fill_memory_ex(pattern, sizeof(pattern), 'a', 'z' - 'a' + 1);
 
-	const uint16_t u16 = 0xabcd;
 	TEST_NESTED_NLATTR_OBJECT(fd, nlh0, hdrlen,
 				  init_ifinfomsg, print_ifinfomsg,
 				  IFLA_BRPORT_PRIORITY, pattern, u16,
 				  printf("%u", u16));
 
-	const uint64_t u64 = 0xabcdedeeefeafeab;
 	TEST_NESTED_NLATTR_OBJECT(fd, nlh0, hdrlen,
 				  init_ifinfomsg, print_ifinfomsg,
 				  IFLA_BRPORT_MESSAGE_AGE_TIMER, pattern, u64,

tests/nlattr_ifla_port.c

@@ -88,7 +88,7 @@ main(void)
 	skip_if_unavailable("/proc/self/fd/");
 
 	const int fd = create_nl_socket(NETLINK_ROUTE);
-	void *nlh0 = tail_alloc(NLMSG_SPACE(hdrlen));
+	void *nlh0 = midtail_alloc(NLMSG_SPACE(hdrlen), 2 * NLA_HDRLEN + 8);
 
 	static char pattern[4096];
 	fill_memory_ex(pattern, sizeof(pattern), 'a', 'z' - 'a' + 1);

tests/nlattr_ifla_xdp.c

@@ -87,13 +87,14 @@ main(void)
 {
 	skip_if_unavailable("/proc/self/fd/");
 
+	const int32_t num = 0xabacdbcd;
 	const int fd = create_nl_socket(NETLINK_ROUTE);
-	void *nlh0 = tail_alloc(NLMSG_SPACE(hdrlen));
+	void *nlh0 = midtail_alloc(NLMSG_SPACE(hdrlen),
+				   NLA_HDRLEN + sizeof(num));
 
 	static char pattern[4096];
 	fill_memory_ex(pattern, sizeof(pattern), 'a', 'z' - 'a' + 1);
 
-	const int32_t num = 0xabacdbcd;
 	TEST_NESTED_NLATTR_OBJECT(fd, nlh0, hdrlen,
 				  init_ifinfomsg, print_ifinfomsg,
 				  IFLA_XDP_FD, pattern, num,

tests/nlattr_inet_diag_msg.c

@@ -87,19 +87,46 @@ main(void)
 {
 	skip_if_unavailable("/proc/self/fd/");
 
-	const int fd = create_nl_socket(NETLINK_SOCK_DIAG);
-	const unsigned int hdrlen = sizeof(struct inet_diag_msg);
-	void *const nlh0 = tail_alloc(NLMSG_SPACE(hdrlen));
-
-	static char pattern[4096];
-	fill_memory_ex(pattern, sizeof(pattern), 'a', 'z' - 'a' + 1);
-
 	static const struct inet_diag_meminfo minfo = {
 		.idiag_rmem = 0xfadcacdb,
 		.idiag_wmem = 0xbdabcada,
 		.idiag_fmem = 0xbadbfafb,
 		.idiag_tmem = 0xfdacdadf
 	};
+	static const struct tcpvegas_info vegas = {
+		.tcpv_enabled = 0xfadcacdb,
+		.tcpv_rttcnt = 0xbdabcada,
+		.tcpv_rtt = 0xbadbfafb,
+		.tcpv_minrtt = 0xfdacdadf
+	};
+	static const struct tcp_dctcp_info dctcp = {
+		.dctcp_enabled = 0xfdac,
+		.dctcp_ce_state = 0xfadc,
+		.dctcp_alpha = 0xbdabcada,
+		.dctcp_ab_ecn = 0xbadbfafb,
+		.dctcp_ab_tot = 0xfdacdadf
+	};
+	static const struct tcp_bbr_info bbr = {
+		.bbr_bw_lo = 0xfdacdadf,
+		.bbr_bw_hi = 0xfadcacdb,
+		.bbr_min_rtt = 0xbdabcada,
+		.bbr_pacing_gain = 0xbadbfafb,
+		.bbr_cwnd_gain = 0xfdacdadf
+	};
+	static const uint32_t mem[] = { 0xaffacbad, 0xffadbcab };
+	static uint32_t bigmem[SK_MEMINFO_VARS + 1];
+	static const uint32_t mark = 0xabdfadca;
+	static const uint8_t shutdown = 0xcd;
+
+	const int fd = create_nl_socket(NETLINK_SOCK_DIAG);
+	const unsigned int hdrlen = sizeof(struct inet_diag_msg);
+	void *const nlh0 = midtail_alloc(NLMSG_SPACE(hdrlen),
+					 NLA_HDRLEN +
+					 MAX(sizeof(bigmem), DEFAULT_STRLEN));
+
+	static char pattern[4096];
+	fill_memory_ex(pattern, sizeof(pattern), 'a', 'z' - 'a' + 1);
+
 	TEST_NLATTR_OBJECT(fd, nlh0, hdrlen,
 			   init_inet_diag_msg, print_inet_diag_msg,
 			   INET_DIAG_MEMINFO, pattern, minfo,
@@ -109,12 +136,6 @@ main(void)
 			   PRINT_FIELD_U(", ", minfo, idiag_tmem);
 			   printf("}"));
 
-	static const struct tcpvegas_info vegas = {
-		.tcpv_enabled = 0xfadcacdb,
-		.tcpv_rttcnt = 0xbdabcada,
-		.tcpv_rtt = 0xbadbfafb,
-		.tcpv_minrtt = 0xfdacdadf
-	};
 	TEST_NLATTR_OBJECT(fd, nlh0, hdrlen,
 			   init_inet_diag_msg, print_inet_diag_msg,
 			   INET_DIAG_VEGASINFO, pattern, vegas,
@@ -125,13 +146,6 @@ main(void)
 			   printf("}"));
 
 
-	static const struct tcp_dctcp_info dctcp = {
-		.dctcp_enabled = 0xfdac,
-		.dctcp_ce_state = 0xfadc,
-		.dctcp_alpha = 0xbdabcada,
-		.dctcp_ab_ecn = 0xbadbfafb,
-		.dctcp_ab_tot = 0xfdacdadf
-	};
 	TEST_NLATTR_OBJECT(fd, nlh0, hdrlen,
 			   init_inet_diag_msg, print_inet_diag_msg,
 			   INET_DIAG_DCTCPINFO, pattern, dctcp,
@@ -142,13 +156,6 @@ main(void)
 			   PRINT_FIELD_U(", ", dctcp, dctcp_ab_tot);
 			   printf("}"));
 
-	static const struct tcp_bbr_info bbr = {
-		.bbr_bw_lo = 0xfdacdadf,
-		.bbr_bw_hi = 0xfadcacdb,
-		.bbr_min_rtt = 0xbdabcada,
-		.bbr_pacing_gain = 0xbadbfafb,
-		.bbr_cwnd_gain = 0xfdacdadf
-	};
 	TEST_NLATTR_OBJECT(fd, nlh0, hdrlen,
 			   init_inet_diag_msg, print_inet_diag_msg,
 			   INET_DIAG_BBRINFO, pattern, bbr,
@@ -159,12 +166,10 @@ main(void)
 			   PRINT_FIELD_U(", ", bbr, bbr_cwnd_gain);
 			   printf("}"));
 
-	static const uint32_t mem[] = { 0xaffacbad, 0xffadbcab };
 	TEST_NLATTR_ARRAY(fd, nlh0, hdrlen,
 			  init_inet_diag_msg, print_inet_diag_msg,
 			  INET_DIAG_SKMEMINFO, pattern, mem, print_uint);
 
-	static uint32_t bigmem[SK_MEMINFO_VARS + 1];
 	memcpy(bigmem, pattern, sizeof(bigmem));
 
 	TEST_NLATTR(fd, nlh0, hdrlen, init_inet_diag_msg, print_inet_diag_msg,
@@ -176,7 +181,6 @@ main(void)
 		    }
 		    printf(", ...]"));
 
-	static const uint32_t mark = 0xabdfadca;
 	TEST_NLATTR_OBJECT(fd, nlh0, hdrlen,
 			   init_inet_diag_msg, print_inet_diag_msg,
 			   INET_DIAG_MARK, pattern, mark,
@@ -187,7 +191,6 @@ main(void)
 			   INET_DIAG_CLASS_ID, pattern, mark,
 			   printf("%u", mark));
 
-	static const uint8_t shutdown = 0xcd;
 	TEST_NLATTR(fd, nlh0, hdrlen,
 		    init_inet_diag_msg, print_inet_diag_msg, INET_DIAG_SHUTDOWN,
 		    sizeof(shutdown), &shutdown, sizeof(shutdown),

tests/nlattr_inet_diag_req_compat.c

@@ -86,7 +86,7 @@ main(void)
 
 	int fd = create_nl_socket(NETLINK_SOCK_DIAG);
 	const unsigned int hdrlen = sizeof(struct inet_diag_req);
-	void *nlh0 = tail_alloc(NLMSG_SPACE(hdrlen));
+	void *nlh0 = midtail_alloc(NLMSG_SPACE(hdrlen), NLA_HDRLEN + 4);
 
 	static char pattern[4096];
 	fill_memory_ex(pattern, sizeof(pattern), 'a', 'z' - 'a' + 1);

tests/nlattr_inet_diag_req_v2.c

@@ -407,7 +407,10 @@ main(void)
 	skip_if_unavailable("/proc/self/fd/");
 
 	int fd = create_nl_socket(NETLINK_SOCK_DIAG);
-	nlh0 = tail_alloc(NLMSG_SPACE(hdrlen));
+	nlh0 = midtail_alloc(NLMSG_SPACE(hdrlen), NLA_HDRLEN +
+			sizeof(struct inet_diag_bc_op) +
+				sizeof(struct inet_diag_hostcond) +
+				sizeof(struct in6_addr) + DEFAULT_STRLEN);
 	fill_memory_ex(pattern, sizeof(pattern), 'a', 'z' - 'a' + 1);
 
 	test_inet_diag_bc_op(fd);

tests/nlattr_mdba_mdb_entry.c

@@ -99,7 +99,12 @@ main(void)
 
 	const int fd = create_nl_socket(NETLINK_ROUTE);
 
-	void *nlh0 = tail_alloc(NLMSG_SPACE(hdrlen));
+	void *nlh0 = midtail_alloc(NLMSG_SPACE(hdrlen), NLA_HDRLEN + 4
+# ifdef HAVE_STRUCT_BR_MDB_ENTRY
+			- 4 + NLA_HDRLEN * 2 + sizeof(struct nlattr)
+			+ sizeof(struct br_mdb_entry)
+# endif
+			);
 
 	static char pattern[4096];
 	fill_memory_ex(pattern, sizeof(pattern), 'a', 'z' - 'a' + 1);

tests/nlattr_mdba_router_port.c

@@ -87,25 +87,27 @@ main(void)
 {
 	skip_if_unavailable("/proc/self/fd/");
 
-	const int fd = create_nl_socket(NETLINK_ROUTE);
-
-	void *nlh0 = tail_alloc(NLMSG_SPACE(hdrlen));
-
-	static char pattern[4096];
-	fill_memory_ex(pattern, sizeof(pattern), 'a', 'z' - 'a' + 1);
-
 	const uint32_t ifindex = ifindex_lo();
-	TEST_NESTED_NLATTR_OBJECT(fd, nlh0, hdrlen,
-				  init_br_port_msg, print_br_port_msg,
-				  MDBA_ROUTER_PORT, pattern, ifindex,
-				  printf(IFINDEX_LO_STR));
-
 	const uint8_t type = MDB_RTR_TYPE_DISABLED;
 	static const struct nlattr nla = {
 		.nla_len = NLA_HDRLEN + sizeof(type),
 		.nla_type = MDBA_ROUTER_PATTR_TYPE
 	};
 	char buf[NLMSG_ALIGN(ifindex) + NLA_HDRLEN + sizeof(type)];
+
+	const int fd = create_nl_socket(NETLINK_ROUTE);
+
+	void *nlh0 = midtail_alloc(NLMSG_SPACE(hdrlen),
+				   NLA_HDRLEN + sizeof(buf));
+
+	static char pattern[4096];
+	fill_memory_ex(pattern, sizeof(pattern), 'a', 'z' - 'a' + 1);
+
+	TEST_NESTED_NLATTR_OBJECT(fd, nlh0, hdrlen,
+				  init_br_port_msg, print_br_port_msg,
+				  MDBA_ROUTER_PORT, pattern, ifindex,
+				  printf(IFINDEX_LO_STR));
+
 	memcpy(buf, &ifindex, sizeof(ifindex));
 	memcpy(buf + NLMSG_ALIGN(ifindex), &nla, sizeof(nla));
 	memcpy(buf + NLMSG_ALIGN(ifindex) + NLA_HDRLEN, &type, sizeof(type));

tests/nlattr_ndmsg.c

@@ -77,7 +77,8 @@ main(void)
 
 	const int fd = create_nl_socket(NETLINK_ROUTE);
 	const unsigned int hdrlen = sizeof(struct ndmsg);
-	void *nlh0 = tail_alloc(NLMSG_SPACE(hdrlen));
+	void *nlh0 = midtail_alloc(NLMSG_SPACE(hdrlen),
+				   NLA_HDRLEN + sizeof(struct nda_cacheinfo));
 
 	static char pattern[4096];
 	fill_memory_ex(pattern, sizeof(pattern), 'a', 'z' - 'a' + 1);

tests/nlattr_ndtmsg.c

@@ -68,7 +68,7 @@ main(void)
 
 	const int fd = create_nl_socket(NETLINK_ROUTE);
 	const unsigned int hdrlen = sizeof(struct ndtmsg);
-	void *nlh0 = tail_alloc(NLMSG_SPACE(hdrlen));
+	void *nlh0 = midtail_alloc(NLMSG_SPACE(hdrlen), NLA_HDRLEN + 11 * 8);
 
 	static char pattern[4096];
 	fill_memory_ex(pattern, sizeof(pattern), 'a', 'z' - 'a' + 1);

tests/nlattr_netconfmsg.c

@@ -66,7 +66,7 @@ main(void)
 	const int fd = create_nl_socket(NETLINK_ROUTE);
 
 	const unsigned int hdrlen = sizeof(struct netconfmsg);
-	void *nlh0 = tail_alloc(NLMSG_SPACE(hdrlen));
+	void *nlh0 = midtail_alloc(NLMSG_SPACE(hdrlen), NLA_HDRLEN + 4);
 
 	static char pattern[4096];
 	fill_memory_ex(pattern, sizeof(pattern), 'a', 'z' - 'a' + 1);

tests/nlattr_netlink_diag_msg.c

@@ -76,27 +76,32 @@ main(void)
 {
 	skip_if_unavailable("/proc/self/fd/");
 
-	const int fd = create_nl_socket(NETLINK_SOCK_DIAG);
-	const unsigned int hdrlen = sizeof(struct netlink_diag_msg);
-	void *const nlh0 = tail_alloc(NLMSG_SPACE(hdrlen));
-
-	static char pattern[4096];
-	fill_memory_ex(pattern, sizeof(pattern), 'a', 'z' - 'a' + 1);
-
 	static const unsigned long groups[] = {
 		(unsigned long) 0xdeadbeefbadc0dedULL,
 		(unsigned long) 0xdeadbeefbadc0dedULL
 	};
-	TEST_NLATTR_ARRAY(fd, nlh0, hdrlen,
-			  init_netlink_diag_msg, print_netlink_diag_msg,
-			  NETLINK_DIAG_GROUPS, pattern, groups, print_xlong);
-
 	static const struct netlink_diag_ring ndr = {
 		.ndr_block_size = 0xfabfabdc,
 		.ndr_block_nr = 0xabcdabda,
 		.ndr_frame_size = 0xcbadbafa,
 		.ndr_frame_nr = 0xdbcafadb
 	};
+	static const uint32_t flags =
+		NDIAG_FLAG_CB_RUNNING | NDIAG_FLAG_PKTINFO;
+
+	const int fd = create_nl_socket(NETLINK_SOCK_DIAG);
+	const unsigned int hdrlen = sizeof(struct netlink_diag_msg);
+	void *const nlh0 = midtail_alloc(NLMSG_SPACE(hdrlen),
+					 NLA_HDRLEN +
+					 MAX(sizeof(groups), sizeof(ndr)));
+
+	static char pattern[4096];
+	fill_memory_ex(pattern, sizeof(pattern), 'a', 'z' - 'a' + 1);
+
+	TEST_NLATTR_ARRAY(fd, nlh0, hdrlen,
+			  init_netlink_diag_msg, print_netlink_diag_msg,
+			  NETLINK_DIAG_GROUPS, pattern, groups, print_xlong);
+
 	TEST_NLATTR_OBJECT(fd, nlh0, hdrlen,
 			   init_netlink_diag_msg, print_netlink_diag_msg,
 			   NETLINK_DIAG_RX_RING, pattern, ndr,
@@ -106,8 +111,6 @@ main(void)
 			   PRINT_FIELD_U(", ", ndr, ndr_frame_nr);
 			   printf("}"));
 
-	static const uint32_t flags =
-		NDIAG_FLAG_CB_RUNNING | NDIAG_FLAG_PKTINFO;
 	TEST_NLATTR_OBJECT(fd, nlh0, hdrlen,
 			   init_netlink_diag_msg, print_netlink_diag_msg,
 			   NETLINK_DIAG_FLAGS, pattern, flags,

tests/nlattr_nlmsgerr.c

@@ -69,11 +69,13 @@ main(void)
 {
 	skip_if_unavailable("/proc/self/fd/");
 
+	static const uint8_t cookie[] = { 0xab, 0xfe };
+
 	const int fd = create_nl_socket(NETLINK_SOCK_DIAG);
 	const unsigned int hdrlen = sizeof(struct nlmsgerr);
-	void *const nlh0 = tail_alloc(NLMSG_SPACE(hdrlen));
+	void *const nlh0 = midtail_alloc(NLMSG_SPACE(hdrlen),
+			NLA_HDRLEN + sizeof(cookie));
 
-	static const uint8_t cookie[] = { 0xab, 0xfe };
 	TEST_NLATTR(fd, nlh0, hdrlen,
 		    init_nlmsgerr, print_nlmsgerr,
 		    NLMSGERR_ATTR_COOKIE,

tests/nlattr_packet_diag_msg.c

@@ -98,13 +98,6 @@ main(void)
 {
 	skip_if_unavailable("/proc/self/fd/");
 
-	int fd = create_nl_socket(NETLINK_SOCK_DIAG);
-	const unsigned int hdrlen = sizeof(struct packet_diag_msg);
-	void *const nlh0 = tail_alloc(NLMSG_SPACE(hdrlen));
-
-	static char pattern[4096];
-	fill_memory_ex(pattern, sizeof(pattern), 'a', 'z' - 'a' + 1);
-
 	static const struct packet_diag_info pinfo = {
 		.pdi_index = 0xabcddafa,
 		.pdi_version = 0xbabcdafb,
@@ -113,16 +106,6 @@ main(void)
 		.pdi_tstamp = 0xeafbaadf,
 		.pdi_flags = PDI_RUNNING
 	};
-	TEST_NLATTR_OBJECT(fd, nlh0, hdrlen,
-			   init_packet_diag_msg, print_packet_diag_msg,
-			   PACKET_DIAG_INFO, pattern, pinfo,
-			   PRINT_FIELD_U("{", pinfo, pdi_index);
-			   PRINT_FIELD_U(", ", pinfo, pdi_version);
-			   PRINT_FIELD_U(", ", pinfo, pdi_reserve);
-			   PRINT_FIELD_U(", ", pinfo, pdi_copy_thresh);
-			   PRINT_FIELD_U(", ", pinfo, pdi_tstamp);
-			   printf(", pdi_flags=PDI_RUNNING}"));
-
 	const struct packet_diag_mclist dml[] = {
 		{
 			.pdmc_index = ifindex_lo(),
@@ -139,11 +122,6 @@ main(void)
 			.pdmc_addr = "5678"
 		}
 	};
-	TEST_NLATTR_ARRAY(fd, nlh0, hdrlen,
-			  init_packet_diag_msg, print_packet_diag_msg,
-			  PACKET_DIAG_MCLIST, pattern, dml,
-			  print_packet_diag_mclist);
-
 	static const struct packet_diag_ring pdr = {
 		.pdr_block_size = 0xabcdafed,
 		.pdr_block_nr = 0xbcadefae,
@@ -153,6 +131,30 @@ main(void)
 		.pdr_sizeof_priv = 0xfeadeacd,
 		.pdr_features = 0xadebadea
 	};
+
+	int fd = create_nl_socket(NETLINK_SOCK_DIAG);
+	const unsigned int hdrlen = sizeof(struct packet_diag_msg);
+	void *const nlh0 = midtail_alloc(NLMSG_SPACE(hdrlen),
+					 NLA_HDRLEN + sizeof(dml));
+
+	static char pattern[4096];
+	fill_memory_ex(pattern, sizeof(pattern), 'a', 'z' - 'a' + 1);
+
+	TEST_NLATTR_OBJECT(fd, nlh0, hdrlen,
+			   init_packet_diag_msg, print_packet_diag_msg,
+			   PACKET_DIAG_INFO, pattern, pinfo,
+			   PRINT_FIELD_U("{", pinfo, pdi_index);
+			   PRINT_FIELD_U(", ", pinfo, pdi_version);
+			   PRINT_FIELD_U(", ", pinfo, pdi_reserve);
+			   PRINT_FIELD_U(", ", pinfo, pdi_copy_thresh);
+			   PRINT_FIELD_U(", ", pinfo, pdi_tstamp);
+			   printf(", pdi_flags=PDI_RUNNING}"));
+
+	TEST_NLATTR_ARRAY(fd, nlh0, hdrlen,
+			  init_packet_diag_msg, print_packet_diag_msg,
+			  PACKET_DIAG_MCLIST, pattern, dml,
+			  print_packet_diag_mclist);
+
 	TEST_NLATTR_OBJECT(fd, nlh0, hdrlen,
 			   init_packet_diag_msg, print_packet_diag_msg,
 			   PACKET_DIAG_RX_RING, pattern, pdr,

tests/nlattr_rtgenmsg.c

@@ -66,13 +66,14 @@ main(void)
 
 	const int fd = create_nl_socket(NETLINK_ROUTE);
 	const unsigned int hdrlen = sizeof(struct rtgenmsg);
-	void *nlh0 = tail_alloc(NLMSG_SPACE(hdrlen));
+	const unsigned int nla_type = 0xffff & NLA_TYPE_MASK;
+	char nla_type_str[256];
+	void *nlh0 = midtail_alloc(NLMSG_SPACE(hdrlen),
+				   NLA_HDRLEN + sizeof(nla_type_str));
 
 	static char pattern[4096];
 	fill_memory_ex(pattern, sizeof(pattern), 'a', 'z' - 'a' + 1);
 
-	const unsigned int nla_type = 0xffff & NLA_TYPE_MASK;
-	char nla_type_str[256];
 	sprintf(nla_type_str, "%#x /* NETNSA_??? */", nla_type);
 	TEST_NLATTR_(fd, nlh0, hdrlen,
 		     init_rtgenmsg, print_rtgenmsg,

tests/nlattr_rtmsg.c

@@ -81,13 +81,14 @@ main(void)
 
 	const int fd = create_nl_socket(NETLINK_ROUTE);
 	const unsigned int hdrlen = sizeof(struct rtmsg);
-	void *nlh0 = tail_alloc(NLMSG_SPACE(hdrlen));
+	const unsigned int nla_type = 0xffff & NLA_TYPE_MASK;
+	char nla_type_str[256];
+	void *nlh0 = midtail_alloc(NLMSG_SPACE(hdrlen),
+				   NLA_HDRLEN + sizeof(nla_type_str));
 
 	static char pattern[4096];
 	fill_memory_ex(pattern, sizeof(pattern), 'a', 'z' - 'a' + 1);
 
-	const unsigned int nla_type = 0xffff & NLA_TYPE_MASK;
-	char nla_type_str[256];
 	sprintf(nla_type_str, "%#x /* RTA_??? */", nla_type);
 	TEST_NLATTR_(fd, nlh0, hdrlen,
 		     init_rtmsg, print_rtmsg,

tests/nlattr_smc_diag_msg.c

@@ -97,13 +97,6 @@ int main(void)
 {
 	skip_if_unavailable("/proc/self/fd/");
 
-	int fd = create_nl_socket(NETLINK_SOCK_DIAG);
-	const unsigned int hdrlen = sizeof(struct smc_diag_msg);
-	void *const nlh0 = tail_alloc(NLMSG_SPACE(hdrlen));
-
-	static char pattern[4096];
-	fill_memory_ex(pattern, sizeof(pattern), 'a', 'z' - 'a' + 1);
-
 	static const struct smc_diag_conninfo cinfo = {
 		.token = 0xabcdefac,
 		.sndbuf_size = 0xbcdaefad,
@@ -149,6 +142,25 @@ int main(void)
 			.count = 0xcdedbad7
 		}
 	};
+	static const struct smc_diag_lgrinfo linfo = {
+		.lnk[0] = {
+			.link_id = 0xaf,
+			.ibport = 0xfa,
+			.ibname = "123",
+			.gid = "456",
+			.peer_gid = "789"
+		},
+		.role = SMC_CLNT
+	};
+
+	int fd = create_nl_socket(NETLINK_SOCK_DIAG);
+	const unsigned int hdrlen = sizeof(struct smc_diag_msg);
+	void *const nlh0 = midtail_alloc(NLMSG_SPACE(hdrlen),
+					 NLA_HDRLEN +
+					 MAX(sizeof(cinfo), sizeof(linfo)));
+
+	static char pattern[4096];
+	fill_memory_ex(pattern, sizeof(pattern), 'a', 'z' - 'a' + 1);
 
 	TEST_NLATTR_OBJECT(fd, nlh0, hdrlen,
 			   init_smc_diag_msg, print_smc_diag_msg,
@@ -170,16 +182,6 @@ int main(void)
 			   PRINT_FIELD_SMC_DIAG_CURSOR(", ", cinfo, tx_fin);
 			   printf("}"));
 
-	static const struct smc_diag_lgrinfo linfo = {
-		.lnk[0] = {
-			.link_id = 0xaf,
-			.ibport = 0xfa,
-			.ibname = "123",
-			.gid = "456",
-			.peer_gid = "789"
-		},
-		.role = SMC_CLNT
-	};
 	TEST_NLATTR_OBJECT(fd, nlh0, hdrlen,
 			   init_smc_diag_msg, print_smc_diag_msg,
 			   SMC_DIAG_LGRINFO, pattern, linfo,

tests/nlattr_tc_stats.c

@@ -77,7 +77,7 @@ main(void)
 	skip_if_unavailable("/proc/self/fd/");
 
 	const int fd = create_nl_socket(NETLINK_ROUTE);
-	void *nlh0 = tail_alloc(NLMSG_SPACE(hdrlen));
+	void *nlh0 = midtail_alloc(NLMSG_SPACE(hdrlen), NLA_HDRLEN + 8 * 5);
 
 	static char pattern[4096];
 	fill_memory_ex(pattern, sizeof(pattern), 'a', 'z' - 'a' + 1);

tests/nlattr_tca_stab.c

@@ -87,7 +87,11 @@ main(void)
 	skip_if_unavailable("/proc/self/fd/");
 
 	const int fd = create_nl_socket(NETLINK_ROUTE);
-	void *nlh0 = tail_alloc(NLMSG_SPACE(hdrlen));
+	void *nlh0 = midtail_alloc(NLMSG_SPACE(hdrlen), NLA_HDRLEN + 4
+#ifdef HAVE_STRUCT_TC_SIZESPEC
+			- 4 + sizeof(struct tc_sizespec)
+#endif
+			);
 
 	static char pattern[4096];
 	fill_memory_ex(pattern, sizeof(pattern), 'a', 'z' - 'a' + 1);

tests/nlattr_tcamsg.c

@@ -62,7 +62,7 @@ main(void)
 
 	const int fd = create_nl_socket(NETLINK_ROUTE);
 	const unsigned int hdrlen = sizeof(struct tcamsg);
-	void *nlh0 = tail_alloc(NLMSG_SPACE(hdrlen));
+	void *nlh0 = midtail_alloc(NLMSG_SPACE(hdrlen), NLA_HDRLEN + 4);
 
 	static char pattern[4096];
 	fill_memory_ex(pattern, sizeof(pattern), 'a', 'z' - 'a' + 1);

tests/nlattr_tcmsg.c

@@ -68,7 +68,8 @@ main(void)
 
 	const int fd = create_nl_socket(NETLINK_ROUTE);
 	const unsigned int hdrlen = sizeof(struct tcmsg);
-	void *nlh0 = tail_alloc(NLMSG_SPACE(hdrlen));
+	void *nlh0 = midtail_alloc(NLMSG_SPACE(hdrlen),
+				   NLA_HDRLEN + sizeof(struct tc_stats));
 
 	static char pattern[4096];
 	fill_memory_ex(pattern, sizeof(pattern), 'a', 'z' - 'a' + 1);

tests/nlattr_unix_diag_msg.c

@@ -75,17 +75,24 @@ main(void)
 {
 	skip_if_unavailable("/proc/self/fd/");
 
-	const int fd = create_nl_socket(NETLINK_SOCK_DIAG);
-	const unsigned int hdrlen = sizeof(struct unix_diag_msg);
-	void *const nlh0 = tail_alloc(NLMSG_SPACE(hdrlen));
-
-	static char pattern[4096];
-	fill_memory_ex(pattern, sizeof(pattern), 'a', 'z' - 'a' + 1);
-
 	static const struct unix_diag_vfs uv = {
 		.udiag_vfs_dev = 0xabcddafa,
 		.udiag_vfs_ino = 0xbafabcda
 	};
+	static const struct unix_diag_rqlen rql = {
+		.udiag_rqueue = 0xfabdcdad,
+		.udiag_wqueue = 0xbacdadcf
+	};
+	static const uint32_t inode[] = { 0xadbcadbc, 0xfabdcdac };
+
+	const int fd = create_nl_socket(NETLINK_SOCK_DIAG);
+	const unsigned int hdrlen = sizeof(struct unix_diag_msg);
+	void *const nlh0 = midtail_alloc(NLMSG_SPACE(hdrlen),
+					 NLA_HDRLEN + sizeof(inode));
+
+	static char pattern[4096];
+	fill_memory_ex(pattern, sizeof(pattern), 'a', 'z' - 'a' + 1);
+
 	TEST_NLATTR_OBJECT(fd, nlh0, hdrlen,
 			   init_unix_diag_msg, print_unix_diag_msg,
 			   UNIX_DIAG_VFS, pattern, uv,
@@ -95,10 +102,6 @@ main(void)
 			   PRINT_FIELD_U(", ", uv, udiag_vfs_ino);
 			   printf("}"));
 
-	static const struct unix_diag_rqlen rql = {
-		.udiag_rqueue = 0xfabdcdad,
-		.udiag_wqueue = 0xbacdadcf
-	};
 	TEST_NLATTR_OBJECT(fd, nlh0, hdrlen,
 			   init_unix_diag_msg, print_unix_diag_msg,
 			   UNIX_DIAG_RQLEN, pattern, rql,
@@ -106,7 +109,6 @@ main(void)
 			   PRINT_FIELD_U(", ", rql, udiag_wqueue);
 			   printf("}"));
 
-	static const uint32_t inode[] = { 0xadbcadbc, 0xfabdcdac };
 	TEST_NLATTR_ARRAY(fd, nlh0, hdrlen,
 			  init_unix_diag_msg, print_unix_diag_msg,
 			  UNIX_DIAG_ICONS, pattern, inode, print_uint);

tests/tests.h

@@ -117,6 +117,9 @@ void *tail_alloc(const size_t)
 void *tail_memdup(const void *, const size_t)
 	ATTRIBUTE_MALLOC ATTRIBUTE_ALLOC_SIZE((2));
 
+#define midtail_alloc(after_, before_) \
+	((void *) ((char *) tail_alloc(((before_) + (after_))) + (before_)))
+
 /*
  * Allocate an object of the specified type at the end
  * of a mapped memory region.