[PATCH 1/1] af_packet: Raw socket destruction warning fix

[Maninder Singh]

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.nar...@samsung.com>
Signed-off-by: Amit Nagal <amit.na...@samsung.com>
Signed-off-by: Maninder Singh <maninder...@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