* [ldv-project] [net] libertas: potential race condition @ 2016-06-07 9:30 Pavel Andrianov 2016-06-07 14:39 ` Dan Williams 0 siblings, 1 reply; 6+ messages in thread From: Pavel Andrianov @ 2016-06-07 9:30 UTC (permalink / raw) To: Kalle Valo Cc: libertas-dev, linux-wireless, netdev, linux-kernel, vaishali.thakkar, LDV list Hi! There is a potential race condition in drivers/net/wireless/libertas/libertas.ko. In the function lbs_hard_start_xmit(..), line 159, a socket buffer is written to priv->current_skb with a spin_lock protection. In the function lbs_mac_event_disconnected(..), lines 50-51, the field current_skb is cleaned. There is no protection used. The corresponding handlers are activated at the same time in lbs_start_card(..) and then may be executed simultaneously. Note, there are two structures lbs_netdev_ops and mesh_netdev_ops, which have the target handler lbs_hard_start_xmit. Is it a real race or I have missed something? -- Pavel Andrianov Linux Verification Center, ISPRAS web: http://linuxtesting.org e-mail: andrianov@ispras.ru ^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [ldv-project] [net] libertas: potential race condition 2016-06-07 9:30 [ldv-project] [net] libertas: potential race condition Pavel Andrianov @ 2016-06-07 14:39 ` Dan Williams 2016-06-07 14:54 ` Pavel Andrianov 2016-06-07 22:51 ` James Cameron 0 siblings, 2 replies; 6+ messages in thread From: Dan Williams @ 2016-06-07 14:39 UTC (permalink / raw) To: Pavel Andrianov, Kalle Valo Cc: libertas-dev, LDV list, netdev, linux-wireless, linux-kernel, vaishali.thakkar On Tue, 2016-06-07 at 13:30 +0400, Pavel Andrianov wrote: > Hi! > > There is a potential race condition in > drivers/net/wireless/libertas/libertas.ko. > In the function lbs_hard_start_xmit(..), line 159, a socket buffer > is > written to priv->current_skb with a spin_lock protection. > In the function lbs_mac_event_disconnected(..), lines 50-51, the > field > current_skb is cleaned. There is no protection used. The > corresponding > handlers are activated at the same time in lbs_start_card(..) and > then > may be executed simultaneously. Note, there are two structures > lbs_netdev_ops and mesh_netdev_ops, which have the target handler > lbs_hard_start_xmit. > Is it a real race or I have missed something? Yeah, it looks like it should be grabbing priv->driver_lock before clearing priv->currenttxskb in lbs_mac_event_disconnected(). Care to submit a patch after testing? Do you have any of that hardware? Dan ^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [ldv-project] [net] libertas: potential race condition 2016-06-07 14:39 ` Dan Williams @ 2016-06-07 14:54 ` Pavel Andrianov 2016-06-07 22:51 ` James Cameron 1 sibling, 0 replies; 6+ messages in thread From: Pavel Andrianov @ 2016-06-07 14:54 UTC (permalink / raw) To: Dan Williams Cc: Kalle Valo, libertas-dev, ldv-project, netdev, linux-wireless, linux-kernel, vaishali.thakkar 07.06.2016 18:39, Dan Williams пишет: > On Tue, 2016-06-07 at 13:30 +0400, Pavel Andrianov wrote: >> Hi! >> >> There is a potential race condition in >> drivers/net/wireless/libertas/libertas.ko. >> In the function lbs_hard_start_xmit(..), line 159, a socket buffer >> is >> written to priv->current_skb with a spin_lock protection. >> In the function lbs_mac_event_disconnected(..), lines 50-51, the >> field >> current_skb is cleaned. There is no protection used. The >> corresponding >> handlers are activated at the same time in lbs_start_card(..) and >> then >> may be executed simultaneously. Note, there are two structures >> lbs_netdev_ops and mesh_netdev_ops, which have the target handler >> lbs_hard_start_xmit. >> Is it a real race or I have missed something? > Yeah, it looks like it should be grabbing priv->driver_lock before > clearing priv->currenttxskb in lbs_mac_event_disconnected(). Care to > submit a patch after testing? Do you have any of that hardware? > > Dan I have no that hardware and I have some doubts about the simple fix, you've suggested. For instance, in lbs_hard_start_xmit the lock is acquired twice and the priv->tx_pending_len can be modified also by lbs_mac_event_disconnected (even if spin_lock will be added to lbs_mac_event_disconnected). Moreover, the function lbs_send_tx_feedback also cleaned priv->currenttxskb, but it happens also without any protection. Thus, the fix has to be more complicated, and I have no ideas about it. -- Pavel Andrianov Linux Verification Center, ISPRAS web: http://linuxtesting.org e-mail: andrianov@ispras.ru ^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [ldv-project] [net] libertas: potential race condition 2016-06-07 14:39 ` Dan Williams 2016-06-07 14:54 ` Pavel Andrianov @ 2016-06-07 22:51 ` James Cameron 2016-06-14 13:16 ` Pavel Andrianov 1 sibling, 1 reply; 6+ messages in thread From: James Cameron @ 2016-06-07 22:51 UTC (permalink / raw) To: Dan Williams Cc: Pavel Andrianov, Kalle Valo, libertas-dev, LDV list, netdev, linux-wireless, linux-kernel, vaishali.thakkar On Tue, Jun 07, 2016 at 09:39:55AM -0500, Dan Williams wrote: > On Tue, 2016-06-07 at 13:30 +0400, Pavel Andrianov wrote: > > Hi! > > > > There is a potential race condition in > > drivers/net/wireless/libertas/libertas.ko. > > In the function lbs_hard_start_xmit(..), line 159, a socket buffer > > is > > written to priv->current_skb with a spin_lock protection. > > In the function lbs_mac_event_disconnected(..), lines 50-51, the > > field > > current_skb is cleaned. There is no protection used. The > > corresponding > > handlers are activated at the same time in lbs_start_card(..) and > > then > > may be executed simultaneously. Note, there are two structures > > lbs_netdev_ops and mesh_netdev_ops, which have the target handler > > lbs_hard_start_xmit. > > Is it a real race or I have missed something? > > Yeah, it looks like it should be grabbing priv->driver_lock before > clearing priv->currenttxskb in lbs_mac_event_disconnected(). Care to > submit a patch after testing? Do you have any of that hardware? I've hardware, with serial console. Can test any patch, on USB (8388) or SDIO (8686). -- James Cameron http://quozl.netrek.org/ ^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [ldv-project] [net] libertas: potential race condition 2016-06-07 22:51 ` James Cameron @ 2016-06-14 13:16 ` Pavel Andrianov 2016-06-15 0:46 ` James Cameron 0 siblings, 1 reply; 6+ messages in thread From: Pavel Andrianov @ 2016-06-14 13:16 UTC (permalink / raw) To: James Cameron Cc: Dan Williams, Kalle Valo, libertas-dev, LDV list, netdev, linux-wireless, linux-kernel, vaishali.thakkar [-- Attachment #1: Type: text/plain, Size: 1353 bytes --] 08.06.2016 02:51, James Cameron пишет: > On Tue, Jun 07, 2016 at 09:39:55AM -0500, Dan Williams wrote: >> On Tue, 2016-06-07 at 13:30 +0400, Pavel Andrianov wrote: >>> Hi! >>> >>> There is a potential race condition in >>> drivers/net/wireless/libertas/libertas.ko. >>> In the function lbs_hard_start_xmit(..), line 159, a socket buffer >>> is >>> written to priv->current_skb with a spin_lock protection. >>> In the function lbs_mac_event_disconnected(..), lines 50-51, the >>> field >>> current_skb is cleaned. There is no protection used. The >>> corresponding >>> handlers are activated at the same time in lbs_start_card(..) and >>> then >>> may be executed simultaneously. Note, there are two structures >>> lbs_netdev_ops and mesh_netdev_ops, which have the target handler >>> lbs_hard_start_xmit. >>> Is it a real race or I have missed something? >> Yeah, it looks like it should be grabbing priv->driver_lock before >> clearing priv->currenttxskb in lbs_mac_event_disconnected(). Care to >> submit a patch after testing? Do you have any of that hardware? > I've hardware, with serial console. > > Can test any patch, on USB (8388) or SDIO (8686). > Hi! I've prepare the patch for this issue. Could you test it? Thank you. -- Pavel Andrianov Linux Verification Center, ISPRAS web: http://linuxtesting.org e-mail: andrianov@ispras.ru [-- Attachment #2: 0001-libertas-Add-spinlock-to-avoid-race-condition.patch --] [-- Type: text/x-patch, Size: 1329 bytes --] >From b1a9e157ccdf8650da93844fd2dbdb6fca509b59 Mon Sep 17 00:00:00 2001 From: Pavel <andrianov@ispras.ru> Date: Tue, 14 Jun 2016 16:59:00 +0400 Subject: [PATCH] libertas: Add spinlock to avoid race condition lbs_mac_event_disconnected may free priv->currenttxskb while lbs_hard_start_xmit accesses to it. The patch adds a spinlock for mutual exclusion. Signed-off-by: Pavel <andrianov@ispras.ru> --- drivers/net/wireless/marvell/libertas/cmdresp.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/drivers/net/wireless/marvell/libertas/cmdresp.c b/drivers/net/wireless/marvell/libertas/cmdresp.c index c95bf6d..c67ae07 100644 --- a/drivers/net/wireless/marvell/libertas/cmdresp.c +++ b/drivers/net/wireless/marvell/libertas/cmdresp.c @@ -27,6 +27,8 @@ void lbs_mac_event_disconnected(struct lbs_private *priv, bool locally_generated) { + unsigned long flags; + if (priv->connect_status != LBS_CONNECTED) return; @@ -46,9 +48,11 @@ void lbs_mac_event_disconnected(struct lbs_private *priv, netif_carrier_off(priv->dev); /* Free Tx and Rx packets */ + spin_lock_irqsave(&priv->driver_lock, flags); kfree_skb(priv->currenttxskb); priv->currenttxskb = NULL; priv->tx_pending_len = 0; + spin_unlock_irqrestore(&priv->driver_lock, flags); priv->connect_status = LBS_DISCONNECTED; -- 1.7.11.7 ^ permalink raw reply related [flat|nested] 6+ messages in thread
* Re: [ldv-project] [net] libertas: potential race condition 2016-06-14 13:16 ` Pavel Andrianov @ 2016-06-15 0:46 ` James Cameron 0 siblings, 0 replies; 6+ messages in thread From: James Cameron @ 2016-06-15 0:46 UTC (permalink / raw) To: Pavel Andrianov Cc: Dan Williams, Kalle Valo, libertas-dev, LDV list, netdev, linux-wireless, linux-kernel, vaishali.thakkar On Tue, Jun 14, 2016 at 05:16:11PM +0400, Pavel Andrianov wrote: > 08.06.2016 02:51, James Cameron пишет: > >On Tue, Jun 07, 2016 at 09:39:55AM -0500, Dan Williams wrote: > >>On Tue, 2016-06-07 at 13:30 +0400, Pavel Andrianov wrote: > >>>Hi! > >>> > >>>There is a potential race condition in > >>>drivers/net/wireless/libertas/libertas.ko. > >>>In the function lbs_hard_start_xmit(..), line 159, a socket buffer > >>>is > >>>written to priv->current_skb with a spin_lock protection. > >>>In the function lbs_mac_event_disconnected(..), lines 50-51, the > >>>field > >>>current_skb is cleaned. There is no protection used. The > >>>corresponding > >>>handlers are activated at the same time in lbs_start_card(..) and > >>>then > >>>may be executed simultaneously. Note, there are two structures > >>>lbs_netdev_ops and mesh_netdev_ops, which have the target handler > >>>lbs_hard_start_xmit. > >>>Is it a real race or I have missed something? > >>Yeah, it looks like it should be grabbing priv->driver_lock before > >>clearing priv->currenttxskb in lbs_mac_event_disconnected(). Care to > >>submit a patch after testing? Do you have any of that hardware? > >I've hardware, with serial console. > > > >Can test any patch, on USB (8388) or SDIO (8686). > > > Hi! > > I've prepare the patch for this issue. Could you test it? > > Thank you. Tested on OLPC XO-1 (usb8388) and XO-1.5 (sd8686) with v4.7-rc3. Confirmed that lbs_mac_event_disconnected is being called on the station when hostapd on access point is given SIGHUP. Longer duration test was; - SSH to station and run "top -d 0.2", - send SIGHUP every six seconds, for 300 cycles, You may add my; Tested-by: James Cameron <quozl@laptop.org> -- James Cameron http://quozl.netrek.org/ ^ permalink raw reply [flat|nested] 6+ messages in thread
end of thread, other threads:[~2016-06-15 0:47 UTC | newest] Thread overview: 6+ messages (download: mbox.gz / follow: Atom feed) -- links below jump to the message on this page -- 2016-06-07 9:30 [ldv-project] [net] libertas: potential race condition Pavel Andrianov 2016-06-07 14:39 ` Dan Williams 2016-06-07 14:54 ` Pavel Andrianov 2016-06-07 22:51 ` James Cameron 2016-06-14 13:16 ` Pavel Andrianov 2016-06-15 0:46 ` James Cameron
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