[NETFILTER]: xt_hashlimit: fix mask calculation

Shifts larger than the data type are undefined, don't try to shift
an u32 by 32. Also remove some special-casing of bitmasks divisible
by 32.

Based on patch by Jan Engelhardt <jengelh@computergmbh.de>.

Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/netfilter/xt_hashlimit.c b/net/netfilter/xt_hashlimit.c
index dc29007..40d344b 100644 (file)
--- a/net/netfilter/xt_hashlimit.c
+++ b/net/netfilter/xt_hashlimit.c
@@ -466,38 +466,25 @@ static inline void rateinfo_recalc(struct dsthash_ent *dh, unsigned long now)
 
 static inline __be32 maskl(__be32 a, unsigned int l)
 {
-       return htonl(ntohl(a) & ~(~(u_int32_t)0 >> l));
+       return l ? htonl(ntohl(a) & ~0 << (32 - l)) : 0;
 }
 
 #if defined(CONFIG_IP6_NF_IPTABLES) || defined(CONFIG_IP6_NF_IPTABLES_MODULE)
 static void hashlimit_ipv6_mask(__be32 *i, unsigned int p)
 {
        switch (p) {
-       case 0:
-               i[0] = i[1] = 0;
-               i[2] = i[3] = 0;
-               break;
-       case 1 ... 31:
+       case 0 ... 31:
                i[0] = maskl(i[0], p);
                i[1] = i[2] = i[3] = 0;
                break;
-       case 32:
-               i[1] = i[2] = i[3] = 0;
-               break;
-       case 33 ... 63:
+       case 32 ... 63:
                i[1] = maskl(i[1], p - 32);
                i[2] = i[3] = 0;
                break;
-       case 64:
-               i[2] = i[3] = 0;
-               break;
-       case 65 ... 95:
+       case 64 ... 95:
                i[2] = maskl(i[2], p - 64);
                i[3] = 0;
-       case 96:
-               i[3] = 0;
-               break;
-       case 97 ... 127:
+       case 96 ... 127:
                i[3] = maskl(i[3], p - 96);
                break;
        case 128: