netdev - Re: [PATCH net] be2net: Signal that the device cannot transmit during reconfiguration

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]

Date:   Wed, 17 Jul 2019 17:23:40 +0900
From:   Benjamin Poirier <bpoirier@...e.com>
To:     Firo Yang <firo.yang@...e.com>
Cc:     David Miller <davem@...emloft.net>,
        Ajit Khaparde <ajit.khaparde@...adcom.com>,
        Sathya Perla <sathya.perla@...adcom.com>,
        Somnath Kotur <somnath.kotur@...adcom.com>,
        Sriharsha Basavapatna <sriharsha.basavapatna@...adcom.com>,
        Saeed Mahameed <saeedm@...lanox.com>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>
Subject: Re: [PATCH net] be2net: Signal that the device cannot transmit
 during reconfiguration

On 2019/07/17 13:23, Firo Yang wrote:
> I think there is a problem if dev_watchdog() is triggered before netif_carrier_off(). dev_watchdog() might call ->ndo_tx_timeout(), i.e. be_tx_timeout(), if txq timeout  happens. Thus be_tx_timeout() could still be able to access the memory which is being freed by be_update_queues().

Good point. That's a separate problem which would occur in case of real
tx timeout. How about this followup change:

--- a/drivers/net/ethernet/emulex/benet/be_main.c
+++ b/drivers/net/ethernet/emulex/benet/be_main.c
@@ -4698,8 +4698,13 @@ int be_update_queues(struct be_adapter *adapter)
 	int status;
 
 	if (netif_running(netdev)) {
+		/* be_tx_timeout() must not run concurrently with this
+		 * function, synchronize with an already-running dev_watchdog
+		 */
+		netif_tx_lock_bh(netdev);
 		/* device cannot transmit now, avoid dev_watchdog timeouts */
 		netif_carrier_off(netdev);
+		netif_tx_unlock_bh(netdev);
 
 		be_close(netdev);
 	}