From: Dmitry V. Levin <ldv@altlinux.org>
Date: Sun, 16 Sep 2018 21:32:37 +0000 (+0000)
Subject: Workaround signedness bugs in system NLMSG_OK reported by -Wsign-compare
X-Git-Tag: v4.25~12
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=96df4b36f6346f4474d2bb8ef6efd785aa7586e0;p=strace

Workaround signedness bugs in system NLMSG_OK reported by -Wsign-compare

Introduce a replacement for NLMSG_OK provided by <linux/netlink.h> since
that system macro contains signedness bugs that are not going to be fixed.

* netlink.h: Include <stdbool.h>.
(is_nlmsg_ok): New static inline function.
* socketutils.c (receive_responses): Use it instead of NLMSG_OK.
* tests/netlink_inet_diag.c (check_responses): Likewise.
* tests/netlink_netlink_diag.c (check_responses): Likewise.
* tests/netlink_unix_diag.c (check_responses): Likewise.

Closes: https://github.com/strace/strace/issues/79
---

diff --git a/netlink.h b/netlink.h
index 42e7802e..48abe0b8 100644
--- a/netlink.h
+++ b/netlink.h
@@ -29,6 +29,7 @@
 #ifndef STRACE_NETLINK_H
 #define STRACE_NETLINK_H
 
+#include <stdbool.h>
 #include <sys/socket.h>
 #include <linux/netlink.h>
 
@@ -63,4 +64,12 @@
 # define NLA_TYPE_MASK		~(NLA_F_NESTED | NLA_F_NET_BYTEORDER)
 #endif
 
+static inline bool
+is_nlmsg_ok(const struct nlmsghdr *const nlh, const ssize_t len)
+{
+	return len >= (ssize_t) sizeof(*nlh)
+	       && nlh->nlmsg_len >= sizeof(*nlh)
+	       && (size_t) len >= nlh->nlmsg_len;
+}
+
 #endif /* !STRACE_NETLINK_H */
diff --git a/socketutils.c b/socketutils.c
index aa0752c3..c3f28a1b 100644
--- a/socketutils.c
+++ b/socketutils.c
@@ -237,9 +237,9 @@ receive_responses(struct tcb *tcp, const int fd, const unsigned long inode,
 		}
 
 		const struct nlmsghdr *h = &hdr_buf.hdr;
-		if (!NLMSG_OK(h, ret))
+		if (!is_nlmsg_ok(h, ret))
 			return false;
-		for (; NLMSG_OK(h, ret); h = NLMSG_NEXT(h, ret)) {
+		for (; is_nlmsg_ok(h, ret); h = NLMSG_NEXT(h, ret)) {
 			if (h->nlmsg_type != expected_msg_type)
 				return false;
 			const int rc = parser(NLMSG_DATA(h),
diff --git a/tests/netlink_inet_diag.c b/tests/netlink_inet_diag.c
index 8b3d8af0..dc990aeb 100644
--- a/tests/netlink_inet_diag.c
+++ b/tests/netlink_inet_diag.c
@@ -100,8 +100,8 @@ check_responses(const int fd)
 		perror_msg_and_skip("recvmsg");
 
 	struct nlmsghdr *h = &hdr_buf.hdr;
-	if (!NLMSG_OK(h, ret))
-		error_msg_and_skip("!NLMSG_OK");
+	if (!is_nlmsg_ok(h, ret))
+		error_msg_and_skip("!is_nlmsg_ok");
 	if (h->nlmsg_type == NLMSG_ERROR) {
 		const struct nlmsgerr *err = NLMSG_DATA(h);
 		if (h->nlmsg_len < NLMSG_LENGTH(sizeof(*err)))
diff --git a/tests/netlink_netlink_diag.c b/tests/netlink_netlink_diag.c
index a682f7c6..ee651eef 100644
--- a/tests/netlink_netlink_diag.c
+++ b/tests/netlink_netlink_diag.c
@@ -100,8 +100,8 @@ check_responses(const int fd)
 		perror_msg_and_skip("recvmsg");
 
 	struct nlmsghdr *h = &hdr_buf.hdr;
-	if (!NLMSG_OK(h, ret))
-		error_msg_and_skip("!NLMSG_OK");
+	if (!is_nlmsg_ok(h, ret))
+		error_msg_and_skip("!is_nlmsg_ok");
 	if (h->nlmsg_type == NLMSG_ERROR) {
 		const struct nlmsgerr *err = NLMSG_DATA(h);
 		if (h->nlmsg_len < NLMSG_LENGTH(sizeof(*err)))
diff --git a/tests/netlink_unix_diag.c b/tests/netlink_unix_diag.c
index e1509238..f74e7306 100644
--- a/tests/netlink_unix_diag.c
+++ b/tests/netlink_unix_diag.c
@@ -104,8 +104,8 @@ check_responses(const int fd)
 		perror_msg_and_skip("recvmsg");
 
 	struct nlmsghdr *h = &hdr_buf.hdr;
-	if (!NLMSG_OK(h, ret))
-		error_msg_and_skip("!NLMSG_OK");
+	if (!is_nlmsg_ok(h, ret))
+		error_msg_and_skip("!is_nlmsg_ok");
 	if (h->nlmsg_type == NLMSG_ERROR) {
 		const struct nlmsgerr *err = NLMSG_DATA(h);
 		if (h->nlmsg_len < NLMSG_LENGTH(sizeof(*err)))