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 517fb03a0bb891be4a9fe5000418ba96138075cd..99b002586498449a645d5974ff3e1e643e75fe96 100644 (file)
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -4411,7 +4411,7 @@ 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);
 
@@ -4753,7 +4753,7 @@ 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);
 
@@ -5135,7 +5135,7 @@ 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;
@@ -5165,7 +5165,7 @@ 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);