1 files changed, 17 insertions, 9 deletions

diff --git a/sbin/ip6fw/ip6fw.c b/sbin/ip6fw/ip6fw.c
index 9c3a7e5aa096..c6307344f336 100644
--- a/sbin/ip6fw/ip6fw.c
+++ b/sbin/ip6fw/ip6fw.c
@@ -37,6 +37,7 @@
 #include <string.h>
 #include <time.h>
 #include <unistd.h>
+#include <errno.h>
 
 #include <net/if.h>
 #include <netinet/in.h>
@@ -410,18 +411,25 @@ list(ac, av)
 	int	ac;
 	char 	**av;
 {
-	struct ip6_fw *r;
-	struct ip6_fw rules[1024];
+	struct ip6_fw *r, *rules;
 	int l,i;
 	unsigned long rulenum;
-	int bytes;
+	int nalloc, bytes, maxbytes;
 
-	/* extract rules from kernel */
-	memset(rules,0,sizeof rules);
-	bytes = sizeof rules;
-	i = getsockopt(s, IPPROTO_IPV6, IPV6_FW_GET, rules, &bytes);
-	if (i < 0)
-		err(2,"getsockopt(IPV6_FW_GET)");
+	/* extract rules from kernel, resizing array as necessary */
+	rules = NULL;
+	nalloc = sizeof *rules;
+	bytes = nalloc;
+	maxbytes = 65536 * sizeof *rules;
+	while (bytes >= nalloc) {
+		nalloc = nalloc * 2 + 200;
+		bytes = nalloc;
+		if ((rules = realloc(rules, bytes)) == NULL)
+			err(2, "realloc");
+		i = getsockopt(s, IPPROTO_IPV6, IPV6_FW_GET, rules, &bytes);
+		if ((i < 0 && errno != EINVAL) || nalloc > maxbytes)
+			err(2, "getsockopt(IPV6_FW_GET)");
+	}
 	if (!ac) {
 		/* display all rules */
 		for (r = rules, l = bytes; l >= sizeof rules[0];