arp: fix a regression in arp_solicit()

Sedat reported the following commit caused a regression:

commit 9650388b5c56578fdccc79c57a8c82fb92b8e7f1
Author: Eric Dumazet <edumazet@google.com>
Date:   Fri Dec 21 07:32:10 2012 +0000

    ipv4: arp: fix a lockdep splat in arp_solicit

This is due to the 6th parameter of arp_send() needs to be NULL
for the broadcast case, the above commit changed it to an all-zero
array by mistake.

Reported-by: Sedat Dilek <sedat.dilek@gmail.com>
Tested-by: Sedat Dilek <sedat.dilek@gmail.com>
Cc: Sedat Dilek <sedat.dilek@gmail.com>
Cc: Eric Dumazet <edumazet@google.com>
Cc: David S. Miller <davem@davemloft.net>
Cc: Julian Anastasov <ja@ssi.bg>
Signed-off-by: Cong Wang <xiyou.wangcong@gmail.com>
Acked-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/ipv4/arp.c b/net/ipv4/arp.c
index 1169ed41d5877f641086309bdb4cf3eebdc173c3..9547a273b9e9829692e85d89627a66eee5d182b9 100644 (file)
--- a/net/ipv4/arp.c
+++ b/net/ipv4/arp.c
@@ -321,7 +321,7 @@ static void arp_error_report(struct neighbour *neigh, struct sk_buff *skb)
 static void arp_solicit(struct neighbour *neigh, struct sk_buff *skb)
 {
        __be32 saddr = 0;
-       u8 dst_ha[MAX_ADDR_LEN];
+       u8 dst_ha[MAX_ADDR_LEN], *dst_hw = NULL;
        struct net_device *dev = neigh->dev;
        __be32 target = *(__be32 *)neigh->primary_key;
        int probes = atomic_read(&neigh->probes);
@@ -364,8 +364,8 @@ static void arp_solicit(struct neighbour *neigh, struct sk_buff *skb)
                if (!(neigh->nud_state & NUD_VALID))
                        pr_debug("trying to ucast probe in NUD_INVALID\n");
                neigh_ha_snapshot(dst_ha, neigh, dev);
+               dst_hw = dst_ha;
        } else {
-               memset(dst_ha, 0, dev->addr_len);
                probes -= neigh->parms->app_probes;
                if (probes < 0) {
 #ifdef CONFIG_ARPD
@@ -376,7 +376,7 @@ static void arp_solicit(struct neighbour *neigh, struct sk_buff *skb)
        }
 
        arp_send(ARPOP_REQUEST, ETH_P_ARP, target, dev, saddr,
-                dst_ha, dev->dev_addr, NULL);
+                dst_hw, dev->dev_addr, NULL);
 }
 
 static int arp_ignore(struct in_device *in_dev, __be32 sip, __be32 tip)