[PATCH 1/1] Fix dst_neigh_lookup/dst_neigh_lookup_skb return value handling bug

[PATCH 1/1] Fix dst_neigh_lookup/dst_neigh_lookup_skb return value handling bug

[Zhouyi Zhou]

Tested on my x86_64 machine

Signed-off-by: Zhouyi Zhou <zhouzhouyi-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
---
 drivers/infiniband/hw/cxgb4/cm.c |   12 ++++++++++++
 include/net/dst.h                |    6 ++++--
 2 files changed, 16 insertions(+), 2 deletions(-)

diff --git a/drivers/infiniband/hw/cxgb4/cm.c b/drivers/infiniband/hw/cxgb4/cm.c
index 565bfb1..6b95851 100644
--- a/drivers/infiniband/hw/cxgb4/cm.c
+++ b/drivers/infiniband/hw/cxgb4/cm.c
@@ -1575,6 +1575,12 @@ static int c4iw_reconnect(struct c4iw_ep *ep)
 
 	neigh = dst_neigh_lookup(ep->dst,
 			&ep->com.cm_id->remote_addr.sin_addr.s_addr);
+	if (!neigh) {
+		pr_err("%s - cannot alloc neigh.\n", __func__);
+		err = -ENOMEM;
+		goto fail4;
+	}
+
 	/* get a l2t entry */
 	if (neigh->dev->flags & IFF_LOOPBACK) {
 		PDBG("%s LOOPBACK\n", __func__);
@@ -3053,6 +3059,12 @@ static int rx_pkt(struct c4iw_dev *dev, struct sk_buff *skb)
 	dst = &rt->dst;
 	neigh = dst_neigh_lookup_skb(dst, skb);
 
+	if (!neigh) {
+		pr_err("%s - failed to allocate neigh!\n",
+		       __func__);
+		goto free_dst;
+	}
+
 	if (neigh->dev->flags & IFF_LOOPBACK) {
 		pdev = ip_dev_find(&init_net, iph->daddr);
 		e = cxgb4_l2t_get(dev->rdev.lldi.l2t, neigh,
diff --git a/include/net/dst.h b/include/net/dst.h
index 853cda1..c083b5a 100644
--- a/include/net/dst.h
+++ b/include/net/dst.h
@@ -413,13 +413,15 @@ static inline int dst_neigh_output(struct dst_entry *dst, struct neighbour *n,
 
 static inline struct neighbour *dst_neigh_lookup(const struct dst_entry *dst, const void *daddr)
 {
-	return dst->ops->neigh_lookup(dst, NULL, daddr);
+	struct neighbour *n = dst->ops->neigh_lookup(dst, NULL, daddr);
+	return IS_ERR(n) ? NULL : n;
 }
 
 static inline struct neighbour *dst_neigh_lookup_skb(const struct dst_entry *dst,
 						     struct sk_buff *skb)
 {
-	return dst->ops->neigh_lookup(dst, skb, NULL);
+	struct neighbour *n =  dst->ops->neigh_lookup(dst, skb, NULL);
+	return IS_ERR(n) ? NULL : n;
 }
 
 static inline void dst_link_failure(struct sk_buff *skb)
-- 
1.7.10.4

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Re: [PATCH 1/1] Fix dst_neigh_lookup/dst_neigh_lookup_skb return value handling bug

[Cong Wang]

On Thu, 14 Mar 2013 at 03:41 GMT, Zhouyi Zhou <zhouzhouyi@gmail.com> wrote:
> Tested on my x86_64 machine
>
> Signed-off-by: Zhouyi Zhou <zhouzhouyi@gmail.com>
> ---
>  drivers/infiniband/hw/cxgb4/cm.c |   12 ++++++++++++
>  include/net/dst.h                |    6 ++++--
>  2 files changed, 16 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/infiniband/hw/cxgb4/cm.c b/drivers/infiniband/hw/cxgb4/cm.c
> index 565bfb1..6b95851 100644
> --- a/drivers/infiniband/hw/cxgb4/cm.c
> +++ b/drivers/infiniband/hw/cxgb4/cm.c
> @@ -1575,6 +1575,12 @@ static int c4iw_reconnect(struct c4iw_ep *ep)
>  
>  	neigh = dst_neigh_lookup(ep->dst,
>  			&ep->com.cm_id->remote_addr.sin_addr.s_addr);
> +	if (!neigh) {
> +		pr_err("%s - cannot alloc neigh.\n", __func__);
> +		err = -ENOMEM;
> +		goto fail4;


You don't need to print error messages for OOM, the mm subsystem will
do.

Re: [PATCH 1/1] Fix dst_neigh_lookup/dst_neigh_lookup_skb return value handling bug

[Steve Wise]

Acked-by: Steve Wise <swise-7bPotxP6k4+P2YhJcF5u+vpXobYPEAuW@public.gmane.org>
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Re: [PATCH 1/1] Fix dst_neigh_lookup/dst_neigh_lookup_skb return value handling bug

[Zhouyi Zhou]

Cong Wang <xiyou.wangcong@gmail.com>  wrote
>>  	neigh = dst_neigh_lookup(ep->dst,
>>  			&ep->com.cm_id->remote_addr.sin_addr.s_addr);
>> +	if (!neigh) {
>> +		pr_err("%s - cannot alloc neigh.\n", __func__);
>> +		err = -ENOMEM;
>> +		goto fail4;

>You don't need to print error messages for OOM, the mm subsystem will
>do.
Thanks for reviewing,  I clone these error messages print from the code
that follows:
   1612         if (!ep->l2t) {
   1613                 pr_err("%s - cannot alloc l2e.\n", __func__);
   1614                 err = -ENOMEM;
   1615                 goto fail4;
   1616         }