net: Fix data-races around netdev_tstamp_prequeue.

While reading netdev_tstamp_prequeue, it can be changed concurrently.
Thus, we need to add READ_ONCE() to its readers.

Fixes: 3b098e2d7c69 ("net: Consistent skb timestamping")
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/core/dev.c b/net/core/dev.c
index 07da69c1ac0a437c8f7b78ba8b938806e1a56d6a..4705e6630efa3e46f51a1f90b73405e448b2e654 100644 (file)
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -4928,7 +4928,7 @@ static int netif_rx_internal(struct sk_buff *skb)
 {
        int ret;
 
-       net_timestamp_check(netdev_tstamp_prequeue, skb);
+       net_timestamp_check(READ_ONCE(netdev_tstamp_prequeue), skb);
 
        trace_netif_rx(skb);
 
@@ -5281,7 +5281,7 @@ static int __netif_receive_skb_core(struct sk_buff **pskb, bool pfmemalloc,
        int ret = NET_RX_DROP;
        __be16 type;
 
-       net_timestamp_check(!netdev_tstamp_prequeue, skb);
+       net_timestamp_check(!READ_ONCE(netdev_tstamp_prequeue), skb);
 
        trace_netif_receive_skb(skb);
 
@@ -5664,7 +5664,7 @@ static int netif_receive_skb_internal(struct sk_buff *skb)
 {
        int ret;
 
-       net_timestamp_check(netdev_tstamp_prequeue, skb);
+       net_timestamp_check(READ_ONCE(netdev_tstamp_prequeue), skb);
 
        if (skb_defer_rx_timestamp(skb))
                return NET_RX_SUCCESS;
@@ -5694,7 +5694,7 @@ void netif_receive_skb_list_internal(struct list_head *head)
 
        INIT_LIST_HEAD(&sublist);
        list_for_each_entry_safe(skb, next, head, list) {
-               net_timestamp_check(netdev_tstamp_prequeue, skb);
+               net_timestamp_check(READ_ONCE(netdev_tstamp_prequeue), skb);
                skb_list_del_init(skb);
                if (!skb_defer_rx_timestamp(skb))
                        list_add_tail(&skb->list, &sublist);