lists.openwall.net   lists  /  announce  owl-users  owl-dev  john-users  john-dev  passwdqc-users  yescrypt  popa3d-users  /  oss-security  kernel-hardening  musl  sabotage  tlsify  passwords  /  crypt-dev  xvendor  /  Bugtraq  Full-Disclosure  linux-kernel  linux-netdev  linux-ext4  linux-hardening  linux-cve-announce  PHC 
Open Source and information security mailing list archives
 
Hash Suite: Windows password security audit tool. GUI, reports in PDF.
[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Message-Id: <1559599037-8514-14-git-send-email-hancock@sedsystems.ca>
Date:   Mon,  3 Jun 2019 15:57:12 -0600
From:   Robert Hancock <hancock@...systems.ca>
To:     netdev@...r.kernel.org
Cc:     anirudh@...inx.com, John.Linn@...inx.com,
        Robert Hancock <hancock@...systems.ca>
Subject: [PATCH net-next 13/18] net: axienet: Fix race condition causing TX hang

It is possible that the interrupt handler fires and frees up space in
the TX ring in between checking for sufficient TX ring space and
stopping the TX queue in axienet_start_xmit. If this happens, the
queue wake from the interrupt handler will occur before the queue is
stopped, causing a lost wakeup and the adapter's transmit hanging.

To avoid this, after stopping the queue, check again whether there is
sufficient space in the TX ring. If so, wake up the queue again.

Signed-off-by: Robert Hancock <hancock@...systems.ca>
---
 drivers/net/ethernet/xilinx/xilinx_axienet_main.c | 20 +++++++++++++++++---
 1 file changed, 17 insertions(+), 3 deletions(-)

diff --git a/drivers/net/ethernet/xilinx/xilinx_axienet_main.c b/drivers/net/ethernet/xilinx/xilinx_axienet_main.c
index e26b339..398e7e6 100644
--- a/drivers/net/ethernet/xilinx/xilinx_axienet_main.c
+++ b/drivers/net/ethernet/xilinx/xilinx_axienet_main.c
@@ -621,6 +621,10 @@ static void axienet_start_xmit_done(struct net_device *ndev)
 
 	ndev->stats.tx_packets += packets;
 	ndev->stats.tx_bytes += size;
+
+	/* Matches barrier in axienet_start_xmit */
+	smp_mb();
+
 	netif_wake_queue(ndev);
 }
 
@@ -676,9 +680,19 @@ static inline int axienet_check_tx_bd_space(struct axienet_local *lp,
 	cur_p = &lp->tx_bd_v[lp->tx_bd_tail];
 
 	if (axienet_check_tx_bd_space(lp, num_frag)) {
-		if (!netif_queue_stopped(ndev))
-			netif_stop_queue(ndev);
-		return NETDEV_TX_BUSY;
+		if (netif_queue_stopped(ndev))
+			return NETDEV_TX_BUSY;
+
+		netif_stop_queue(ndev);
+
+		/* Matches barrier in axienet_start_xmit_done */
+		smp_mb();
+
+		/* Space might have just been freed - check again */
+		if (axienet_check_tx_bd_space(lp, num_frag))
+			return NETDEV_TX_BUSY;
+
+		netif_wake_queue(ndev);
 	}
 
 	if (skb->ip_summed == CHECKSUM_PARTIAL) {
-- 
1.8.3.1

Powered by blists - more mailing lists

Powered by Openwall GNU/*/Linux Powered by OpenVZ