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netpoll: hold rcu read lock in __netpoll_send_skb()

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[ Upstream commit 505ead7ab77f289f12d8a68ac83da068e4d4408b ]

The function __netpoll_send_skb() is being invoked without holding the
RCU read lock. This oversight triggers a warning message when
CONFIG_PROVE_RCU_LIST is enabled:

	net/core/netpoll.c:330 suspicious rcu_dereference_check() usage!

	 netpoll_send_skb
	 netpoll_send_udp
	 write_ext_msg
	 console_flush_all
	 console_unlock
	 vprintk_emit

To prevent npinfo from disappearing unexpectedly, ensure that
__netpoll_send_skb() is protected with the RCU read lock.

Fixes: 2899656b49 ("netpoll: take rcu_read_lock_bh() in netpoll_send_skb_on_dev()")
Signed-off-by: Breno Leitao <leitao@debian.org>
Reviewed-by: Simon Horman <horms@kernel.org>
Link: https://patch.msgid.link/20250306-netpoll_rcu_v2-v2-1-bc4f5c51742a@debian.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
Breno Leitao
2025-03-06 05:16:18 -08:00
committed by Greg Kroah-Hartman
parent 6c5bb3f7ac
commit 9d1966bdaf
1 changed files with 7 additions and 2 deletions
Download Patch File Download Diff File Expand all files Collapse all files

9
net/core/netpoll.c
View File

@@ -326,6 +326,7 @@ static int netpoll_owner_active(struct net_device *dev)
static netdev_tx_t __netpoll_send_skb(struct netpoll *np, struct sk_buff *skb)
{
netdev_tx_t status = NETDEV_TX_BUSY;
netdev_tx_t ret = NET_XMIT_DROP;
struct net_device *dev;
unsigned long tries;
/* It is up to the caller to keep npinfo alive. */
@@ -334,11 +335,12 @@ static netdev_tx_t __netpoll_send_skb(struct netpoll *np, struct sk_buff *skb)
lockdep_assert_irqs_disabled();
dev = np->dev;
rcu_read_lock();
npinfo = rcu_dereference_bh(dev->npinfo);
if (!npinfo || !netif_running(dev) || !netif_device_present(dev)) {
dev_kfree_skb_irq(skb);
return NET_XMIT_DROP;
goto out;
}
/* don't get messages out of order, and no recursion */
@@ -377,7 +379,10 @@ static netdev_tx_t __netpoll_send_skb(struct netpoll *np, struct sk_buff *skb)
skb_queue_tail(&npinfo->txq, skb);
schedule_delayed_work(&npinfo->tx_work,0);
}
return NETDEV_TX_OK;
ret = NETDEV_TX_OK;
out:
rcu_read_unlock();
return ret;
}
netdev_tx_t netpoll_send_skb(struct netpoll *np, struct sk_buff *skb)