netfilter: xtables: clean up xt_mac match routine

Signed-off-by: Jan Engelhardt <jengelh@medozas.de>

1 files changed, 10 insertions, 8 deletions

diff --git a/net/netfilter/xt_mac.c b/net/netfilter/xt_mac.c
index c2007116ce5b..2039d0741b37 100644
--- a/net/netfilter/xt_mac.c
+++ b/net/netfilter/xt_mac.c
@@ -26,14 +26,16 @@ MODULE_ALIAS("ip6t_mac");
 
 static bool mac_mt(const struct sk_buff *skb, const struct xt_match_param *par)
 {
-    const struct xt_mac_info *info = par->matchinfo;
-
-    /* Is mac pointer valid? */
-    return skb_mac_header(skb) >= skb->head &&
-           skb_mac_header(skb) + ETH_HLEN <= skb->data
-           /* If so, compare... */
-           && ((!compare_ether_addr(eth_hdr(skb)->h_source, info->srcaddr))
-                ^ info->invert);
+        const struct xt_mac_info *info = par->matchinfo;
+        bool ret;
+
+        if (skb_mac_header(skb) < skb->head)
+                return false;
+        if (skb_mac_header(skb) + ETH_HLEN > skb->data)
+                return false;
+        ret  = compare_ether_addr(eth_hdr(skb)->h_source, info->srcaddr) == 0;
+        ret ^= info->invert;
+        return ret;
 }
 
 static struct xt_match mac_mt_reg __read_mostly = {