Re: [PATCH] ath9k: Protect queue draining by rcu_read_lock()

[Toke Høiland-Jørgensen]

On 24 March 2018 00:00:39 GMT, Ben Greear  wrote:
>On 02/02/2018 02:36 AM, Toke Høiland-Jørgensen wrote:
>> When ath9k was switched over to use the mac80211 intermediate queues,
>> node cleanup now drains the mac80211 queues. However, this call path
>is
>> not protected by rcu_read_lock() as it was previously entirely
>internal
>> to the driver which uses its own locking.
>
>As far as I can tell, this is not currently in Linus' tree.
>
>Was this dropped on purpose?

It was merged quite recently, but hasn't propagated yet:

https://git.kernel.org/pub/scm/linux/kernel/git/kvalo/ath.git/commit/?h=ath-next

-Toke

Re: [PATCH] ath9k: Protect queue draining by rcu_read_lock()

[Ben Greear]

On 02/02/2018 02:36 AM, Toke Høiland-Jørgensen wrote:

When ath9k was switched over to use the mac80211 intermediate queues,
node cleanup now drains the mac80211 queues. However, this call path is
not protected by rcu_read_lock() as it was previously entirely internal
to the driver which uses its own locking.


As far as I can tell, this is not currently in Linus' tree.

Was this dropped on purpose?

Thanks,
Ben



This leads to a possible rcu_dereference() without holding
rcu_read_lock(); but only if a station is cleaned up while having
packets queued on the TXQ. Fix this by adding the rcu_read_lock() to the
caller in ath9k.

Fixes: 50f08edf9809 ("ath9k: Switch to using mac80211 intermediate software 
queues.")
Cc: sta...@vger.kernel.org
Reported-by: Ben Greear 
Signed-off-by: Toke Høiland-Jørgensen 
---
 drivers/net/wireless/ath/ath9k/xmit.c | 4 
 1 file changed, 4 insertions(+)

diff --git a/drivers/net/wireless/ath/ath9k/xmit.c 
b/drivers/net/wireless/ath/ath9k/xmit.c
index 396bf05c6bf6..d8b041f48ca8 100644
--- a/drivers/net/wireless/ath/ath9k/xmit.c
+++ b/drivers/net/wireless/ath/ath9k/xmit.c
@@ -2892,6 +2892,8 @@ void ath_tx_node_cleanup(struct ath_softc *sc, struct 
ath_node *an)
struct ath_txq *txq;
int tidno;

+   rcu_read_lock();
+
for (tidno = 0; tidno < IEEE80211_NUM_TIDS; tidno++) {
tid = ath_node_to_tid(an, tidno);
txq = tid->txq;
@@ -2909,6 +2911,8 @@ void ath_tx_node_cleanup(struct ath_softc *sc, struct 
ath_node *an)
if (!an->sta)
break; /* just one multicast ath_atx_tid */
}
+
+   rcu_read_unlock();
 }

 #ifdef CONFIG_ATH9K_TX99




--
Ben Greear 
Candela Technologies Inc  http://www.candelatech.com

[PATCH] ath9k: Protect queue draining by rcu_read_lock()

[Toke Høiland-Jørgensen]

When ath9k was switched over to use the mac80211 intermediate queues,
node cleanup now drains the mac80211 queues. However, this call path is
not protected by rcu_read_lock() as it was previously entirely internal
to the driver which uses its own locking.

This leads to a possible rcu_dereference() without holding
rcu_read_lock(); but only if a station is cleaned up while having
packets queued on the TXQ. Fix this by adding the rcu_read_lock() to the
caller in ath9k.

Fixes: 50f08edf9809 ("ath9k: Switch to using mac80211 intermediate software 
queues.")
Cc: sta...@vger.kernel.org
Reported-by: Ben Greear 
Signed-off-by: Toke Høiland-Jørgensen 
---
 drivers/net/wireless/ath/ath9k/xmit.c | 4 
 1 file changed, 4 insertions(+)

diff --git a/drivers/net/wireless/ath/ath9k/xmit.c 
b/drivers/net/wireless/ath/ath9k/xmit.c
index 396bf05c6bf6..d8b041f48ca8 100644
--- a/drivers/net/wireless/ath/ath9k/xmit.c
+++ b/drivers/net/wireless/ath/ath9k/xmit.c
@@ -2892,6 +2892,8 @@ void ath_tx_node_cleanup(struct ath_softc *sc, struct 
ath_node *an)
struct ath_txq *txq;
int tidno;
 
+   rcu_read_lock();
+
for (tidno = 0; tidno < IEEE80211_NUM_TIDS; tidno++) {
tid = ath_node_to_tid(an, tidno);
txq = tid->txq;
@@ -2909,6 +2911,8 @@ void ath_tx_node_cleanup(struct ath_softc *sc, struct 
ath_node *an)
if (!an->sta)
break; /* just one multicast ath_atx_tid */
}
+
+   rcu_read_unlock();
 }
 
 #ifdef CONFIG_ATH9K_TX99
-- 
2.16.0