[Patch] arp: fix a regression in arp_solicit()

Subsystems: networking [general], networking [ipv4/ipv6], the rest

STALE5005d REVIEWED: 1 (0M)

1 review trailer.

7 messages, 3 authors, 2012-12-24 · open the first message on its own page

[Patch] arp: fix a regression in arp_solicit()

From: Cong Wang <hidden>
Date: 2012-12-23 14:51:03 

From: Cong Wang <redacted>

Sedat reported the following commit caused a regression:

commit 9650388b5c56578fdccc79c57a8c82fb92b8e7f1
Author: Eric Dumazet [off-list ref]
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 broatcase case, the above commit changed it to all-zero non-NULL
hw addr.

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

---
diff --git a/net/ipv4/arp.c b/net/ipv4/arp.c
index 1169ed4..9547a273 100644
--- 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)

Re: [Patch] arp: fix a regression in arp_solicit()

From: Sedat Dilek <hidden>
Date: 2012-12-23 14:49:59 

On Sun, Dec 23, 2012 at 3:42 PM, Cong Wang [off-list ref] wrote:
From: Cong Wang <redacted>

Sedat reported the following commit caused a regression:

commit 9650388b5c56578fdccc79c57a8c82fb92b8e7f1
Author: Eric Dumazet [off-list ref]
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 broatcase case, the above commit changed it to all-zero non-NULL
hw addr.
s/broatcase/broadcast ?

- Sedat -
quoted hunk
Reported-by: Sedat Dilek <redacted>
Tested-by: Sedat Dilek <redacted>
Cc: Sedat Dilek <redacted>
Cc: Eric Dumazet <edumazet@google.com>
Cc: David S. Miller <davem@davemloft.net>
Cc: Julian Anastasov <ja@ssi.bg>
Signed-off-by: Cong Wang <redacted>

---
diff --git a/net/ipv4/arp.c b/net/ipv4/arp.c
index 1169ed4..9547a273 100644
--- 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)

Re: [Patch] arp: fix a regression in arp_solicit()

From: Sedat Dilek <hidden>
Date: 2012-12-23 14:58:53 

On Sun, Dec 23, 2012 at 3:49 PM, Sedat Dilek [off-list ref] wrote:
On Sun, Dec 23, 2012 at 3:42 PM, Cong Wang [off-list ref] wrote:
quoted
From: Cong Wang <redacted>

Sedat reported the following commit caused a regression:

commit 9650388b5c56578fdccc79c57a8c82fb92b8e7f1
Author: Eric Dumazet [off-list ref]
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 broatcase case, the above commit changed it to all-zero non-NULL
hw addr.
s/broatcase/broadcast ?
While at it you might enhance the label with "ipv4"?

ipv4: arp: fix a regression in arp_solicit()

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

---
diff --git a/net/ipv4/arp.c b/net/ipv4/arp.c
index 1169ed4..9547a273 100644
--- 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)

Re: [Patch] arp: fix a regression in arp_solicit()

From: David Miller <davem@davemloft.net>
Date: 2012-12-23 22:17:07 

From: Sedat Dilek <redacted>
Date: Sun, 23 Dec 2012 15:58:52 +0100

While at it you might enhance the label with "ipv4"?
That's excessive.

ARP is ipv4 and ipv4 only, in other protocols it has completely
different names.

Re: [Patch] arp: fix a regression in arp_solicit()

From: Cong Wang <hidden>
Date: 2012-12-24 01:21:40 

On Mon, Dec 24, 2012 at 6:17 AM, David Miller [off-list ref] wrote:
From: Sedat Dilek <redacted>
Date: Sun, 23 Dec 2012 15:58:52 +0100
quoted
While at it you might enhance the label with "ipv4"?
That's excessive.

ARP is ipv4 and ipv4 only, in other protocols it has completely
different names.
Agreed. I will resend the patch with the typo fixed.

Thanks.

Re: [Patch] arp: fix a regression in arp_solicit()

From: Sedat Dilek <hidden>
Date: 2012-12-24 01:33:21 

On Sun, Dec 23, 2012 at 11:17 PM, David Miller [off-list ref] wrote:
From: Sedat Dilek <redacted>
Date: Sun, 23 Dec 2012 15:58:52 +0100
quoted
While at it you might enhance the label with "ipv4"?
That's excessive.

ARP is ipv4 and ipv4 only, in other protocols it has completely
different names.
OK, I see (shorter subject is always good).
I oriented myself at the original commit from Eric which was labeled the same.
Just had a look at the git-history [1] myself...

- Sedat -

[1] http://git.kernel.org/?p=linux/kernel/git/davem/net.git;a=history;f=net/ipv4/arp.c

Re: [Patch] arp: fix a regression in arp_solicit()

From: Sedat Dilek <hidden>
Date: 2012-12-24 01:44:02 

On Mon, Dec 24, 2012 at 2:33 AM, Sedat Dilek [off-list ref] wrote:
On Sun, Dec 23, 2012 at 11:17 PM, David Miller [off-list ref] wrote:
quoted
From: Sedat Dilek <redacted>
Date: Sun, 23 Dec 2012 15:58:52 +0100
quoted
While at it you might enhance the label with "ipv4"?
That's excessive.

ARP is ipv4 and ipv4 only, in other protocols it has completely
different names.
OK, I see (shorter subject is always good).
I oriented myself at the original commit from Eric which was labeled the same.
Just had a look at the git-history [1] myself...
Hmm, 'man arp' does not mention as IPv4-only.
So, Neighbor Discovery Protocol (NDP) is the "IPv6 equivalent".
Just as a note to myself.

- Sedat -

[1] http://en.wikipedia.org/wiki/Address_Resolution_Protocol
[2] https://kb.wisc.edu/ns/page.php?id=12364

- Sedat -

[1] http://git.kernel.org/?p=linux/kernel/git/davem/net.git;a=history;f=net/ipv4/arp.c
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