[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>

1 files changed, 5 insertions, 18 deletions

diff --git a/net/netfilter/xt_hashlimit.c b/net/netfilter/xt_hashlimit.c
index dc29007c52cd..40d344b21453 100644
--- 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: