Fix wraparound bug introduced in commit 48596a8ddc46

The patch "netfilter: ipset: Fix adding an IPv4 range containing
more than 2^31 addresses" introduced a wraparound bug, which could
lead to memory exhaustion when adding an x.x.x.x-255.255.255.255
range to any hash:*net* types.

Fixes Netfilter's bugzilla id #1212, reported by Thomas Schwark.

1 files changed, 14 insertions, 14 deletions

diff --git a/kernel/net/netfilter/ipset/ip_set_hash_netnet.c b/kernel/net/netfilter/ipset/ip_set_hash_netnet.c
index 7f9ae2e..5a2b923 100644
--- a/kernel/net/netfilter/ipset/ip_set_hash_netnet.c
+++ b/kernel/net/netfilter/ipset/ip_set_hash_netnet.c
@@ -169,8 +169,8 @@ hash_netnet4_uadt(struct ip_set *set, struct nlattr *tb[],
 	ipset_adtfn adtfn = set->variant->adt[adt];
 	struct hash_netnet4_elem e = { };
 	struct ip_set_ext ext = IP_SET_INIT_UEXT(set);
-	u32 ip = 0, ip_to = 0, last;
-	u32 ip2 = 0, ip2_from = 0, ip2_to = 0, last2;
+	u32 ip = 0, ip_to = 0;
+	u32 ip2 = 0, ip2_from = 0, ip2_to = 0;
 	int ret;
 
 	if (tb[IPSET_ATTR_LINENO])
@@ -247,27 +247,27 @@ hash_netnet4_uadt(struct ip_set *set, struct nlattr *tb[],
 		ip_set_mask_from_to(ip2_from, ip2_to, e.cidr[1]);
 	}
 
-	if (retried)
+	if (retried) {
 		ip = ntohl(h->next.ip[0]);
+		ip2 = ntohl(h->next.ip[1]);
+	} else {
+		ip2 = ip2_from;
+	}
 
-	while (ip <= ip_to) {
+	do {
 		e.ip[0] = htonl(ip);
-		last = ip_set_range_to_cidr(ip, ip_to, &e.cidr[0]);
-		ip2 = (retried &&
-		       ip == ntohl(h->next.ip[0])) ? ntohl(h->next.ip[1])
-						   : ip2_from;
-		while (ip2 <= ip2_to) {
+		ip = ip_set_range_to_cidr(ip, ip_to, &e.cidr[0]);
+		do {
 			e.ip[1] = htonl(ip2);
-			last2 = ip_set_range_to_cidr(ip2, ip2_to, &e.cidr[1]);
+			ip2 = ip_set_range_to_cidr(ip2, ip2_to, &e.cidr[1]);
 			ret = adtfn(set, &e, &ext, &ext, flags);
 			if (ret && !ip_set_eexist(ret, flags))
 				return ret;
 
 			ret = 0;
-			ip2 = last2 + 1;
-		}
-		ip = last + 1;
-	}
+		} while (ip2++ < ip2_to);
+		ip2 = ip2_from;
+	} while (ip++ < ip_to);
 	return ret;
 }