From: Dmitry V. Levin <ldv@altlinux.org>
Date: Thu, 19 May 2016 01:23:40 +0000 (+0000)
Subject: Fix one more code pattern that might break gcc strict aliasing rules
X-Git-Tag: v4.12~112
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=7b6979701b5ddda47ba53f82381a5f412708b0ad;p=strace

Fix one more code pattern that might break gcc strict aliasing rules

* socketutils.c (receive_responses): Turn static buffer into a union
to avoid breaking of gcc strict aliasing rules.
* tests/netlink_inet_diag.c (check_responses): Likewise.
* tests/netlink_netlink_diag.c (check_responses): Likewise.
* tests/netlink_unix_diag.c (check_responses): Likewise.
---

diff --git a/socketutils.c b/socketutils.c
index a0d9310d..5d8d3ed9 100644
--- a/socketutils.c
+++ b/socketutils.c
@@ -187,13 +187,17 @@ receive_responses(const int fd, const unsigned long inode,
 		  int (* parser) (const char *, const void *,
 				  int, unsigned long))
 {
-	static long buf[8192 / sizeof(long)];
+	static union {
+		struct nlmsghdr hdr;
+		long buf[8192 / sizeof(long)];
+	} hdr_buf;
+
 	struct sockaddr_nl nladdr = {
 		.nl_family = AF_NETLINK
 	};
 	struct iovec iov = {
-		.iov_base = buf,
-		.iov_len = sizeof(buf)
+		.iov_base = hdr_buf.buf,
+		.iov_len = sizeof(hdr_buf.buf)
 	};
 	int flags = 0;
 
@@ -212,7 +216,7 @@ receive_responses(const int fd, const unsigned long inode,
 			return false;
 		}
 
-		const struct nlmsghdr *h = (struct nlmsghdr *) buf;
+		const struct nlmsghdr *h = &hdr_buf.hdr;
 		if (!NLMSG_OK(h, ret))
 			return false;
 		for (; NLMSG_OK(h, ret); h = NLMSG_NEXT(h, ret)) {
diff --git a/tests/netlink_inet_diag.c b/tests/netlink_inet_diag.c
index 342be072..2332e203 100644
--- a/tests/netlink_inet_diag.c
+++ b/tests/netlink_inet_diag.c
@@ -75,13 +75,17 @@ send_query(const int fd, const int family, const int proto)
 static void
 check_responses(const int fd)
 {
-	static long buf[8192 / sizeof(long)];
+	static union {
+		struct nlmsghdr hdr;
+		long buf[8192 / sizeof(long)];
+	} hdr_buf;
+
 	struct sockaddr_nl nladdr = {
 		.nl_family = AF_NETLINK
 	};
 	struct iovec iov = {
-		.iov_base = buf,
-		.iov_len = sizeof(buf)
+		.iov_base = hdr_buf.buf,
+		.iov_len = sizeof(hdr_buf.buf)
 	};
 	struct msghdr msg = {
 		.msg_name = (void *) &nladdr,
@@ -94,7 +98,7 @@ check_responses(const int fd)
 	if (ret <= 0)
 		perror_msg_and_skip("recvmsg");
 
-	struct nlmsghdr *h = (struct nlmsghdr *) buf;
+	struct nlmsghdr *h = &hdr_buf.hdr;
 	if (!NLMSG_OK(h, ret))
 		error_msg_and_skip("!NLMSG_OK");
 	if (h->nlmsg_type == NLMSG_ERROR) {
diff --git a/tests/netlink_netlink_diag.c b/tests/netlink_netlink_diag.c
index 0afdb5d7..fc32822b 100644
--- a/tests/netlink_netlink_diag.c
+++ b/tests/netlink_netlink_diag.c
@@ -80,13 +80,17 @@ send_query(const int fd)
 static void
 check_responses(const int fd)
 {
-	static long buf[8192 / sizeof(long)];
+	static union {
+		struct nlmsghdr hdr;
+		long buf[8192 / sizeof(long)];
+	} hdr_buf;
+
 	struct sockaddr_nl nladdr = {
 		.nl_family = AF_NETLINK
 	};
 	struct iovec iov = {
-		.iov_base = buf,
-		.iov_len = sizeof(buf)
+		.iov_base = hdr_buf.buf,
+		.iov_len = sizeof(hdr_buf.buf)
 	};
 	struct msghdr msg = {
 		.msg_name = (void *) &nladdr,
@@ -99,7 +103,7 @@ check_responses(const int fd)
 	if (ret <= 0)
 		perror_msg_and_skip("recvmsg");
 
-	struct nlmsghdr *h = (struct nlmsghdr *) buf;
+	struct nlmsghdr *h = &hdr_buf.hdr;
 	if (!NLMSG_OK(h, ret))
 		error_msg_and_skip("!NLMSG_OK");
 	if (h->nlmsg_type == NLMSG_ERROR) {
diff --git a/tests/netlink_unix_diag.c b/tests/netlink_unix_diag.c
index e5ef6fab..b91cbbbe 100644
--- a/tests/netlink_unix_diag.c
+++ b/tests/netlink_unix_diag.c
@@ -83,13 +83,17 @@ send_query(const int fd)
 static void
 check_responses(const int fd)
 {
-	static long buf[8192 / sizeof(long)];
+	static union {
+		struct nlmsghdr hdr;
+		long buf[8192 / sizeof(long)];
+	} hdr_buf;
+
 	struct sockaddr_nl nladdr = {
 		.nl_family = AF_NETLINK
 	};
 	struct iovec iov = {
-		.iov_base = buf,
-		.iov_len = sizeof(buf)
+		.iov_base = hdr_buf.buf,
+		.iov_len = sizeof(hdr_buf.buf)
 	};
 	struct msghdr msg = {
 		.msg_name = (void *) &nladdr,
@@ -102,7 +106,7 @@ check_responses(const int fd)
 	if (ret <= 0)
 		perror_msg_and_skip("recvmsg");
 
-	struct nlmsghdr *h = (struct nlmsghdr *) buf;
+	struct nlmsghdr *h = &hdr_buf.hdr;
 	if (!NLMSG_OK(h, ret))
 		error_msg_and_skip("!NLMSG_OK");
 	if (h->nlmsg_type == NLMSG_ERROR) {