From 682b0ccabdc7970f89544c0d19477515583a5f5b Mon Sep 17 00:00:00 2001
From: Beniamino Galvani <bgalvani@redhat.com>
Date: Thu, 25 Feb 2021 14:38:16 +0100
Subject: [PATCH] libndp,ndptool: use poll() instead of select()

select() doesn't support file descriptors greater than 1023. If the
program has many files open, the socket descriptor can be > 1023 and
then FD_SET(fd, &rfds) causes a buffer overflow.

Switch to poll() and ppoll() which don't have this limitation.

Signed-off-by: Beniamino Galvani <bgalvani@redhat.com>
Signed-off-by: Jiri Pirko <jiri@nvidia.com>
---
 libndp/libndp.c   | 20 +++++++++-----------
 utils/Makefile.am |  2 +-
 utils/Makefile.in |  2 +-
 utils/ndptool.c   | 22 +++++++++-------------
 4 files changed, 20 insertions(+), 26 deletions(-)

diff --git a/libndp/libndp.c b/libndp/libndp.c
index 06a3d23..6314717 100644
--- a/libndp/libndp.c
+++ b/libndp/libndp.c
@@ -25,7 +25,7 @@
 #include <errno.h>
 #include <ctype.h>
 #include <sys/socket.h>
-#include <sys/select.h>
+#include <poll.h>
 #include <netinet/in.h>
 #include <netinet/icmp6.h>
 #include <arpa/inet.h>
@@ -2107,22 +2107,20 @@ int ndp_call_eventfd_handler(struct ndp *ndp)
 NDP_EXPORT
 int ndp_callall_eventfd_handler(struct ndp *ndp)
 {
-	fd_set rfds;
-	int fdmax;
-	struct timeval tv;
-	int fd = ndp_get_eventfd(ndp);
+	struct pollfd pfd;
 	int ret;
 	int err;
 
-	memset(&tv, 0, sizeof(tv));
-	FD_ZERO(&rfds);
-	FD_SET(fd, &rfds);
-	fdmax = fd + 1;
+	pfd = (struct pollfd) {
+		.fd = ndp_get_eventfd(ndp),
+		.events = POLLIN,
+	};
+
 	while (true) {
-		ret = select(fdmax, &rfds, NULL, NULL, &tv);
+		ret = poll(&pfd, 1, 0);
 		if (ret == -1)
 			return -errno;
-		if (!FD_ISSET(fd, &rfds))
+		if (!(pfd.revents & POLLIN))
 			return 0;
 		err = ndp_call_eventfd_handler(ndp);
 		if (err)
diff --git a/utils/Makefile.am b/utils/Makefile.am
index cca00c2..75e452c 100644
--- a/utils/Makefile.am
+++ b/utils/Makefile.am
@@ -2,7 +2,7 @@ MAINTAINERCLEANFILES = Makefile.in
 
 ACLOCAL_AMFLAGS = -I m4
 
-AM_CFLAGS = -I${top_srcdir}/include
+AM_CFLAGS = -I${top_srcdir}/include -D_GNU_SOURCE
 
 ndptool_LDADD = $(top_builddir)/libndp/libndp.la
 
diff --git a/utils/Makefile.in b/utils/Makefile.in
index e339b19..d81de50 100644
--- a/utils/Makefile.in
+++ b/utils/Makefile.in
@@ -294,7 +294,7 @@ top_builddir = @top_builddir@
 top_srcdir = @top_srcdir@
 MAINTAINERCLEANFILES = Makefile.in
 ACLOCAL_AMFLAGS = -I m4
-AM_CFLAGS = -I${top_srcdir}/include
+AM_CFLAGS = -I${top_srcdir}/include -D_GNU_SOURCE
 ndptool_LDADD = $(top_builddir)/libndp/libndp.la
 ndptool_SOURCES = ndptool.c
 all: all-am
diff --git a/utils/ndptool.c b/utils/ndptool.c
index 662ff01..618f167 100644
--- a/utils/ndptool.c
+++ b/utils/ndptool.c
@@ -28,7 +28,7 @@
 #include <arpa/inet.h>
 #include <errno.h>
 #include <ndp.h>
-#include <sys/select.h>
+#include <poll.h>
 
 enum verbosity_level {
 	VERB1,
@@ -59,13 +59,10 @@ static void empty_signal_handler(int signal)
 
 static int run_main_loop(struct ndp *ndp)
 {
-	fd_set rfds;
-	fd_set rfds_tmp;
-	int fdmax;
+	struct pollfd pfd;
 	int ret;
 	struct sigaction siginfo;
 	sigset_t mask;
-	int ndp_fd;
 	int err = 0;
 
 	sigemptyset(&siginfo.sa_mask);
@@ -100,23 +97,22 @@ static int run_main_loop(struct ndp *ndp)
 
 	sigemptyset(&mask);
 
-	FD_ZERO(&rfds);
-	ndp_fd = ndp_get_eventfd(ndp);
-	FD_SET(ndp_fd, &rfds);
-	fdmax = ndp_fd + 1;
+	pfd = (struct pollfd) {
+		.fd = ndp_get_eventfd(ndp),
+		.events = POLLIN,
+	};
 
 	for (;;) {
-		rfds_tmp = rfds;
-		ret = pselect(fdmax, &rfds_tmp, NULL, NULL, NULL, &mask);
+		ret = ppoll(&pfd, 1, NULL, &mask);
 		if (ret == -1) {
 			if (errno == EINTR) {
 				goto out;
 			}
-			pr_err("Select failed\n");
+			pr_err("Poll failed\n");
 			err = -errno;
 			goto out;
 		}
-		if (FD_ISSET(ndp_fd, &rfds_tmp)) {
+		if (pfd.revents & POLLIN) {
 			err = ndp_call_eventfd_handler(ndp);
 			if (err) {
 				pr_err("ndp eventfd handler call failed\n");
-- 
2.26.2