xt_DHCPMAC: correct L2addr set and compare

diff --git a/extensions/xt_DHCPMAC.c b/extensions/xt_DHCPMAC.c
index 5abb452572ed1f6528d7c2bd034a8bb55a5c0d5e..47f9534f74c73f687b6b44d4eac0f5e8a1cd3f01 100644 (file)
--- a/extensions/xt_DHCPMAC.c
+++ b/extensions/xt_DHCPMAC.c
@@ -34,9 +34,9 @@ static void ether_set(unsigned char *addr, const unsigned char *op,
        unsigned int i;
 
        for (i = 0; i < ETH_ALEN && mask > 0; ++i) {
-               lo_mask = mask % 8;
+               lo_mask = (mask >= 8) ? 8 : mask;
                /* FF << 4 >> 4 = 0F */
-               lo_mask = ~(uint8_t)0U << lo_mask >> lo_mask;
+               lo_mask = (uint8_t)(~0U << lo_mask) >> lo_mask;
                addr[i] &= lo_mask;
                addr[i] |= op[i] & ~lo_mask;
                if (mask >= 8)
@@ -55,9 +55,9 @@ static bool ether_cmp(const unsigned char *lh, const unsigned char *rh,
 #define ZMACHEX(s) s[0], s[1], s[2], s[3], s[4], s[5]
 
        for (i = 0; i < ETH_ALEN && mask > 0; ++i) {
-               lo_mask = mask % 8;
+               lo_mask = (mask >= 8) ? 8 : mask;
                /* ~(0xFF << 4 >> 4) = ~0x0F = 0xF0 */
-               lo_mask = ~(~(uint8_t)0U << lo_mask >> lo_mask);
+               lo_mask = ~((uint8_t)(~0U << lo_mask) >> lo_mask);
                if ((lh[i] ^ rh[i]) & lo_mask)
                        return false;
                if (mask >= 8)
@@ -110,13 +110,12 @@ dhcpmac_tg(struct sk_buff *skb, const struct xt_action_param *par)
                return NF_DROP;
 
        for (i = 0; i < sizeof(dh->chaddr); i += 2)
-               csum_replace2(&udph->check, *(const __be16 *)dh->chaddr, 0);
+               csum_replace2(&udph->check, *(const __be16 *)(dh->chaddr + i), 0);
 
-       memset(dh->chaddr, 0, sizeof(dh->chaddr));
        ether_set(dh->chaddr, info->addr, info->mask);
 
        for (i = 0; i < sizeof(dh->chaddr); i += 2)
-               csum_replace2(&udph->check, 0, *(const __be16 *)dh->chaddr);
+               csum_replace2(&udph->check, 0, *(const __be16 *)(dh->chaddr + i));
 
        return XT_CONTINUE;
 }