| Message ID | 20210727214358.466397-1-rajatasthana4@gmail.com (mailing list archive) |
|---|---|
| State | Changes Requested |
| Delegated to: | Kalle Valo |
| Headers | show |
| Series | ath9k_htc: Add a missing spin_lock_init() | expand |
Rajat Asthana <rajatasthana4@gmail.com> writes: > Syzkaller reported a lockdep warning on non-initialized spinlock: > > INFO: trying to register non-static key. > The code is fine but needs lockdep annotation, or maybe > you didn't initialize this object before use? > turning off the locking correctness validator. > CPU: 0 PID: 10 Comm: ksoftirqd/0 Not tainted 5.13.0-rc4-syzkaller #0 > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 > Call Trace: > __dump_stack lib/dump_stack.c:79 [inline] > dump_stack+0x143/0x1db lib/dump_stack.c:120 > assign_lock_key kernel/locking/lockdep.c:937 [inline] > register_lock_class+0x1077/0x1180 kernel/locking/lockdep.c:1249 > __lock_acquire+0x102/0x5230 kernel/locking/lockdep.c:4781 > lock_acquire kernel/locking/lockdep.c:5512 [inline] > lock_acquire+0x19d/0x700 kernel/locking/lockdep.c:5477 > __raw_spin_lock_bh include/linux/spinlock_api_smp.h:135 [inline] > _raw_spin_lock_bh+0x2f/0x40 kernel/locking/spinlock.c:175 > spin_lock_bh include/linux/spinlock.h:359 [inline] > ath9k_wmi_event_tasklet+0x231/0x3f0 drivers/net/wireless/ath/ath9k/wmi.c:172 > tasklet_action_common.constprop.0+0x201/0x2e0 kernel/softirq.c:784 > __do_softirq+0x1b0/0x944 kernel/softirq.c:559 > run_ksoftirqd kernel/softirq.c:921 [inline] > run_ksoftirqd+0x21/0x50 kernel/softirq.c:913 > smpboot_thread_fn+0x3ec/0x870 kernel/smpboot.c:165 > kthread+0x38c/0x460 kernel/kthread.c:313 > ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:294 > > We missed a spin_lock_init() in ath9k_wmi_event_tasklet() when the wmi > event is WMI_TXSTATUS_EVENTID. Placing this init here instead of > ath9k_init_wmi() is fine mainly because we need this spinlock when the > event is WMI_TXSTATUS_EVENTID and hence it should be initialized when it > is needed. > > Signed-off-by: Rajat Asthana <rajatasthana4@gmail.com> > --- > drivers/net/wireless/ath/ath9k/wmi.c | 1 + > 1 file changed, 1 insertion(+) > > diff --git a/drivers/net/wireless/ath/ath9k/wmi.c b/drivers/net/wireless/ath/ath9k/wmi.c > index fe29ad4b9023..446b7ca459df 100644 > --- a/drivers/net/wireless/ath/ath9k/wmi.c > +++ b/drivers/net/wireless/ath/ath9k/wmi.c > @@ -169,6 +169,7 @@ void ath9k_wmi_event_tasklet(struct tasklet_struct *t) > &wmi->drv_priv->fatal_work); > break; > case WMI_TXSTATUS_EVENTID: > + spin_lock_init(&priv->tx.tx_lock); > spin_lock_bh(&priv->tx.tx_lock); > if (priv->tx.flags & ATH9K_HTC_OP_TX_DRAIN) { > spin_unlock_bh(&priv->tx.tx_lock); This is not making sense to me. You need to elaborate in the commit log a lot more why this is "fine". For example, what happens when there are multiple WMI_TXSTATUS_EVENTID events? Did you test this on a real device?
On 28/07/21 12:41 pm, Kalle Valo wrote: > Rajat Asthana <rajatasthana4@gmail.com> writes: > >> Syzkaller reported a lockdep warning on non-initialized spinlock: >> >> INFO: trying to register non-static key. >> The code is fine but needs lockdep annotation, or maybe >> you didn't initialize this object before use? >> turning off the locking correctness validator. >> CPU: 0 PID: 10 Comm: ksoftirqd/0 Not tainted 5.13.0-rc4-syzkaller #0 >> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 >> Call Trace: >> __dump_stack lib/dump_stack.c:79 [inline] >> dump_stack+0x143/0x1db lib/dump_stack.c:120 >> assign_lock_key kernel/locking/lockdep.c:937 [inline] >> register_lock_class+0x1077/0x1180 kernel/locking/lockdep.c:1249 >> __lock_acquire+0x102/0x5230 kernel/locking/lockdep.c:4781 >> lock_acquire kernel/locking/lockdep.c:5512 [inline] >> lock_acquire+0x19d/0x700 kernel/locking/lockdep.c:5477 >> __raw_spin_lock_bh include/linux/spinlock_api_smp.h:135 [inline] >> _raw_spin_lock_bh+0x2f/0x40 kernel/locking/spinlock.c:175 >> spin_lock_bh include/linux/spinlock.h:359 [inline] >> ath9k_wmi_event_tasklet+0x231/0x3f0 drivers/net/wireless/ath/ath9k/wmi.c:172 >> tasklet_action_common.constprop.0+0x201/0x2e0 kernel/softirq.c:784 >> __do_softirq+0x1b0/0x944 kernel/softirq.c:559 >> run_ksoftirqd kernel/softirq.c:921 [inline] >> run_ksoftirqd+0x21/0x50 kernel/softirq.c:913 >> smpboot_thread_fn+0x3ec/0x870 kernel/smpboot.c:165 >> kthread+0x38c/0x460 kernel/kthread.c:313 >> ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:294 >> >> We missed a spin_lock_init() in ath9k_wmi_event_tasklet() when the wmi >> event is WMI_TXSTATUS_EVENTID. Placing this init here instead of >> ath9k_init_wmi() is fine mainly because we need this spinlock when the >> event is WMI_TXSTATUS_EVENTID and hence it should be initialized when it >> is needed. >> >> Signed-off-by: Rajat Asthana <rajatasthana4@gmail.com> >> --- >> drivers/net/wireless/ath/ath9k/wmi.c | 1 + >> 1 file changed, 1 insertion(+) >> >> diff --git a/drivers/net/wireless/ath/ath9k/wmi.c b/drivers/net/wireless/ath/ath9k/wmi.c >> index fe29ad4b9023..446b7ca459df 100644 >> --- a/drivers/net/wireless/ath/ath9k/wmi.c >> +++ b/drivers/net/wireless/ath/ath9k/wmi.c >> @@ -169,6 +169,7 @@ void ath9k_wmi_event_tasklet(struct tasklet_struct *t) >> &wmi->drv_priv->fatal_work); >> break; >> case WMI_TXSTATUS_EVENTID: >> + spin_lock_init(&priv->tx.tx_lock); >> spin_lock_bh(&priv->tx.tx_lock); >> if (priv->tx.flags & ATH9K_HTC_OP_TX_DRAIN) { >> spin_unlock_bh(&priv->tx.tx_lock); > > This is not making sense to me. You need to elaborate in the commit log > a lot more why this is "fine". For example, what happens when there are > multiple WMI_TXSTATUS_EVENTID events? > Thanks for the review! Now that you mentioned the case when there are multiple WMI_TXSTATUS_EVENTID events, this doesn't make sense, as that will cause a race condition. This instead should be done in ath9k_init_wmi(). I will make this change in the v2 patch. > Did you test this on a real device? > No, I didn't test this on a real device. Syzkaller has a reproducer for this and I just relied on the fact that the reproducer did not reproduce the warning with this patch.
Rajat Asthana <rajatasthana4@gmail.com> writes: >> Did you test this on a real device? > > No, I didn't test this on a real device. Syzkaller has a reproducer > for this and I just relied on the fact that the reproducer did not > reproduce the warning with this patch. This is exactly what worries me with syzbot patches. People just try to silence the warning and not thinking how it works on a real device.
diff --git a/drivers/net/wireless/ath/ath9k/wmi.c b/drivers/net/wireless/ath/ath9k/wmi.c index fe29ad4b9023..446b7ca459df 100644 --- a/drivers/net/wireless/ath/ath9k/wmi.c +++ b/drivers/net/wireless/ath/ath9k/wmi.c @@ -169,6 +169,7 @@ void ath9k_wmi_event_tasklet(struct tasklet_struct *t) &wmi->drv_priv->fatal_work); break; case WMI_TXSTATUS_EVENTID: + spin_lock_init(&priv->tx.tx_lock); spin_lock_bh(&priv->tx.tx_lock); if (priv->tx.flags & ATH9K_HTC_OP_TX_DRAIN) { spin_unlock_bh(&priv->tx.tx_lock);
Syzkaller reported a lockdep warning on non-initialized spinlock: INFO: trying to register non-static key. The code is fine but needs lockdep annotation, or maybe you didn't initialize this object before use? turning off the locking correctness validator. CPU: 0 PID: 10 Comm: ksoftirqd/0 Not tainted 5.13.0-rc4-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:79 [inline] dump_stack+0x143/0x1db lib/dump_stack.c:120 assign_lock_key kernel/locking/lockdep.c:937 [inline] register_lock_class+0x1077/0x1180 kernel/locking/lockdep.c:1249 __lock_acquire+0x102/0x5230 kernel/locking/lockdep.c:4781 lock_acquire kernel/locking/lockdep.c:5512 [inline] lock_acquire+0x19d/0x700 kernel/locking/lockdep.c:5477 __raw_spin_lock_bh include/linux/spinlock_api_smp.h:135 [inline] _raw_spin_lock_bh+0x2f/0x40 kernel/locking/spinlock.c:175 spin_lock_bh include/linux/spinlock.h:359 [inline] ath9k_wmi_event_tasklet+0x231/0x3f0 drivers/net/wireless/ath/ath9k/wmi.c:172 tasklet_action_common.constprop.0+0x201/0x2e0 kernel/softirq.c:784 __do_softirq+0x1b0/0x944 kernel/softirq.c:559 run_ksoftirqd kernel/softirq.c:921 [inline] run_ksoftirqd+0x21/0x50 kernel/softirq.c:913 smpboot_thread_fn+0x3ec/0x870 kernel/smpboot.c:165 kthread+0x38c/0x460 kernel/kthread.c:313 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:294 We missed a spin_lock_init() in ath9k_wmi_event_tasklet() when the wmi event is WMI_TXSTATUS_EVENTID. Placing this init here instead of ath9k_init_wmi() is fine mainly because we need this spinlock when the event is WMI_TXSTATUS_EVENTID and hence it should be initialized when it is needed. Signed-off-by: Rajat Asthana <rajatasthana4@gmail.com> --- drivers/net/wireless/ath/ath9k/wmi.c | 1 + 1 file changed, 1 insertion(+)