net: Fix data-races around netdev_tstamp_prequeue.

[ Upstream commit 61adf447e38664447526698872e21c04623afb8e ]

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>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/net/core/dev.c b/net/core/dev.c
index 87cf2e0d8f6f17241399e01f9c83fef88bcc13bc..28f623628876c43a054690be052ca7db07f2e75a 100644 (file)
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -4893,7 +4893,7 @@ 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);
 
@@ -5253,7 +5253,7 @@ 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);
 
@@ -5634,7 +5634,7 @@ 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;
@@ -5664,7 +5664,7 @@ static 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);