net: bridge: don't increment tx_dropped in br_do_proxy_arp

BugLink: https://bugs.launchpad.net/bugs/1878232

commit 85a3d4a9 upstream.

pskb_may_pull may fail due to various reasons (e.g. alloc failure), but the
skb isn't changed/dropped and processing continues so we shouldn't
increment tx_dropped.

CC: Kyeyoon Park <kyeyoonp@codeaurora.org>
CC: Roopa Prabhu <roopa@cumulusnetworks.com>
CC: Stephen Hemminger <stephen@networkplumber.org>
CC: bridge@lists.linux-foundation.org
Fixes: 95850116 ("bridge: Add support for IEEE 802.11 Proxy ARP")
Signed-off-by: Nikolay Aleksandrov <nikolay@cumulusnetworks.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Ian May <ian.may@canonical.com>
Signed-off-by: Kleber Sacilotto de Souza <kleber.souza@canonical.com>

net/bridge/br_input.c

@@ -78,13 +78,10 @@ static void br_do_proxy_arp(struct sk_buff *skb, struct net_bridge *br,
 
 	BR_INPUT_SKB_CB(skb)->proxyarp_replied = false;
 
-	if (dev->flags & IFF_NOARP)
+	if ((dev->flags & IFF_NOARP) ||
+	    !pskb_may_pull(skb, arp_hdr_len(dev)))
 		return;
 
-	if (!pskb_may_pull(skb, arp_hdr_len(dev))) {
-		dev->stats.tx_dropped++;
-		return;
-	}
 	parp = arp_hdr(skb);
 
 	if (parp->ar_pro != htons(ETH_P_IP) ||