* [PATCH 1/1] af_packet: Raw socket destruction warning fix
@ 2016-02-10 12:05 Maninder Singh
2016-02-10 15:09 ` Eric Dumazet
0 siblings, 1 reply; 2+ messages in thread
From: Maninder Singh @ 2016-02-10 12:05 UTC (permalink / raw)
To: davem, willemb, daniel, edumazet, al.drozdov, eyal.birger,
tklauser, fruggeri, dwmw2
Cc: netdev, linux-kernel, ajeet.y, pankaj.m, gh007.kim, hakbong5.lee,
akhilesh.k, Maninder Singh, Vaneet Narang, Amit Nagal
This Patch fixes below warning:-
WARNING: at net/packet/af_packet.c:xxx packet_sock_destruct
There is following race between packet_rcv and packet_close
which keeps unfree packet in receive queue.
CPU 1 CPU2
packet_rcv
packet_close
skb_set_owner_r(skb, sk);
skb_queue_purge(&sk->sk_receive_queue);
spin_lock(&sk->sk_receive_queue.lock);
__skb_queue_tail(&sk->sk_receive_queue, skb);
spin_unlock(&sk->sk_receive_queue.lock);
Signed-off-by: Vaneet Narang <v.narang@samsung.com>
Signed-off-by: Amit Nagal <amit.nagal@samsung.com>
Signed-off-by: Maninder Singh <maninder1.s@samsung.com>
---
net/packet/af_packet.c | 11 +++++++----
1 file changed, 7 insertions(+), 4 deletions(-)
diff --git a/net/packet/af_packet.c b/net/packet/af_packet.c
index 992396a..e6047e6 100644
--- a/net/packet/af_packet.c
+++ b/net/packet/af_packet.c
@@ -1310,7 +1310,10 @@ static int packet_rcv_has_room(struct packet_sock *po, struct sk_buff *skb)
static void packet_sock_destruct(struct sock *sk)
{
+ /* Purge queues */
+
skb_queue_purge(&sk->sk_error_queue);
+ skb_queue_purge(&sk->sk_receive_queue);
WARN_ON(atomic_read(&sk->sk_rmem_alloc));
WARN_ON(atomic_read(&sk->sk_wmem_alloc));
@@ -1991,6 +1994,9 @@ static int packet_rcv(struct sk_buff *skb, struct net_device *dev,
if (!net_eq(dev_net(dev), sock_net(sk)))
goto drop;
+ if (sock_flag(sk, SOCK_DEAD))
+ goto drop;
+
skb->dev = dev;
if (dev->header_ops) {
@@ -2053,7 +2059,6 @@ static int packet_rcv(struct sk_buff *skb, struct net_device *dev,
if (pskb_trim(skb, snaplen))
goto drop_n_acct;
- skb_set_owner_r(skb, sk);
skb->dev = NULL;
skb_dst_drop(skb);
@@ -2061,6 +2066,7 @@ static int packet_rcv(struct sk_buff *skb, struct net_device *dev,
nf_reset(skb);
spin_lock(&sk->sk_receive_queue.lock);
+ skb_set_owner_r(skb, sk);
po->stats.stats1.tp_packets++;
sock_skb_set_dropcount(sk, skb);
__skb_queue_tail(&sk->sk_receive_queue, skb);
@@ -2899,9 +2905,6 @@ static int packet_release(struct socket *sock)
sock_orphan(sk);
sock->sk = NULL;
- /* Purge queues */
-
- skb_queue_purge(&sk->sk_receive_queue);
packet_free_pending(po);
sk_refcnt_debug_release(sk);
--
1.7.9.5
^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [PATCH 1/1] af_packet: Raw socket destruction warning fix
2016-02-10 12:05 [PATCH 1/1] af_packet: Raw socket destruction warning fix Maninder Singh
@ 2016-02-10 15:09 ` Eric Dumazet
0 siblings, 0 replies; 2+ messages in thread
From: Eric Dumazet @ 2016-02-10 15:09 UTC (permalink / raw)
To: Maninder Singh
Cc: davem, willemb, daniel, edumazet, al.drozdov, eyal.birger,
tklauser, fruggeri, dwmw2, netdev, linux-kernel, ajeet.y,
pankaj.m, gh007.kim, hakbong5.lee, akhilesh.k, Vaneet Narang,
Amit Nagal
On Wed, 2016-02-10 at 17:35 +0530, Maninder Singh wrote:
> This Patch fixes below warning:-
> WARNING: at net/packet/af_packet.c:xxx packet_sock_destruct
>
> There is following race between packet_rcv and packet_close
> which keeps unfree packet in receive queue.
>
> CPU 1 CPU2
> packet_rcv
>
> packet_close
> skb_set_owner_r(skb, sk);
>
> skb_queue_purge(&sk->sk_receive_queue);
>
> spin_lock(&sk->sk_receive_queue.lock);
> __skb_queue_tail(&sk->sk_receive_queue, skb);
> spin_unlock(&sk->sk_receive_queue.lock);
This absolutely can not happen.
CPU 1 holds rcu read lock, so cpu 2 can not possibly call
skb_queue_purge()
(cpu 1 is blocked in synchronize_net(), waiting that all cpus are no
longer in packet_rcv())
This patch does not address the root cause of your problem, and only
slightly changes probability for the bug to trigger.
^ permalink raw reply [flat|nested] 2+ messages in thread
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