[PATCH v2 0/2] wifi: ath11k: fix event locking

[PATCH v2 0/2] wifi: ath11k: fix event locking

[Johan Hovold]

RCU lockdep reported suspicious RCU usage when accessing the temperature
sensor. Inspection revealed that the DFS radar event code was also
missing the required RCU read-side critical section marking.

Johan


Changes in v2
 - add the missing rcu_read_unlock() to an
   ath11k_wmi_pdev_temperature_event() error path as noticed by Jeff


Johan Hovold (2):
  wifi: ath11k: fix temperature event locking
  wifi: ath11k: fix dfs radar event locking

 drivers/net/wireless/ath/ath11k/wmi.c | 11 +++++++++--
 1 file changed, 9 insertions(+), 2 deletions(-)

-- 
2.41.0

[PATCH v2 1/2] wifi: ath11k: fix temperature event locking

[Johan Hovold]

The ath11k active pdevs are protected by RCU but the temperature event
handling code calling ath11k_mac_get_ar_by_pdev_id() was not marked as a
read-side critical section as reported by RCU lockdep:

	=============================
	WARNING: suspicious RCU usage
	6.6.0-rc6 #7 Not tainted
	-----------------------------
	drivers/net/wireless/ath/ath11k/mac.c:638 suspicious rcu_dereference_check() usage!

	other info that might help us debug this:

	rcu_scheduler_active = 2, debug_locks = 1
	no locks held by swapper/0/0.
	...
	Call trace:
	...
	 lockdep_rcu_suspicious+0x16c/0x22c
	 ath11k_mac_get_ar_by_pdev_id+0x194/0x1b0 [ath11k]
	 ath11k_wmi_tlv_op_rx+0xa84/0x2c1c [ath11k]
	 ath11k_htc_rx_completion_handler+0x388/0x510 [ath11k]

Mark the code in question as an RCU read-side critical section to avoid
any potential use-after-free issues.

Fixes: a41d10348b01 ("ath11k: add thermal sensor device support")
Cc: stable@vger.kernel.org      # 5.7
Signed-off-by: Johan Hovold <johan+linaro@kernel.org>
---
 drivers/net/wireless/ath/ath11k/wmi.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/drivers/net/wireless/ath/ath11k/wmi.c b/drivers/net/wireless/ath/ath11k/wmi.c
index 23ad6825e5be..da1582b8dc30 100644
--- a/drivers/net/wireless/ath/ath11k/wmi.c
+++ b/drivers/net/wireless/ath/ath11k/wmi.c
@@ -8383,14 +8383,17 @@ ath11k_wmi_pdev_temperature_event(struct ath11k_base *ab,
 	ath11k_dbg(ab, ATH11K_DBG_WMI, "event pdev temperature ev temp %d pdev_id %d\n",
 		   ev->temp, ev->pdev_id);
 
+	rcu_read_lock();
+
 	ar = ath11k_mac_get_ar_by_pdev_id(ab, ev->pdev_id);
 	if (!ar) {
 		ath11k_warn(ab, "invalid pdev id in pdev temperature ev %d", ev->pdev_id);
-		kfree(tb);
-		return;
+		goto exit;
 	}
 
 	ath11k_thermal_event_temperature(ar, ev->temp);
+exit:
+	rcu_read_unlock();
 
 	kfree(tb);
 }
-- 
2.41.0

Re: [PATCH v2 1/2] wifi: ath11k: fix temperature event locking

[Jeff Johnson]

On 10/19/2023 8:31 AM, Johan Hovold wrote:
> The ath11k active pdevs are protected by RCU but the temperature event
> handling code calling ath11k_mac_get_ar_by_pdev_id() was not marked as a
> read-side critical section as reported by RCU lockdep:
> 
> 	=============================
> 	WARNING: suspicious RCU usage
> 	6.6.0-rc6 #7 Not tainted
> 	-----------------------------
> 	drivers/net/wireless/ath/ath11k/mac.c:638 suspicious rcu_dereference_check() usage!
> 
> 	other info that might help us debug this:
> 
> 	rcu_scheduler_active = 2, debug_locks = 1
> 	no locks held by swapper/0/0.
> 	...
> 	Call trace:
> 	...
> 	 lockdep_rcu_suspicious+0x16c/0x22c
> 	 ath11k_mac_get_ar_by_pdev_id+0x194/0x1b0 [ath11k]
> 	 ath11k_wmi_tlv_op_rx+0xa84/0x2c1c [ath11k]
> 	 ath11k_htc_rx_completion_handler+0x388/0x510 [ath11k]
> 
> Mark the code in question as an RCU read-side critical section to avoid
> any potential use-after-free issues.
> 
> Fixes: a41d10348b01 ("ath11k: add thermal sensor device support")
> Cc: stable@vger.kernel.org      # 5.7
> Signed-off-by: Johan Hovold <johan+linaro@kernel.org>
Acked-by: Jeff Johnson <quic_jjohnson@quicinc.com>

Re: [PATCH v2 1/2] wifi: ath11k: fix temperature event locking

[Kalle Valo]

Johan Hovold <johan+linaro@kernel.org> writes:

> The ath11k active pdevs are protected by RCU but the temperature event
> handling code calling ath11k_mac_get_ar_by_pdev_id() was not marked as a
> read-side critical section as reported by RCU lockdep:
>
> 	=============================
> 	WARNING: suspicious RCU usage
> 	6.6.0-rc6 #7 Not tainted
> 	-----------------------------
> 	drivers/net/wireless/ath/ath11k/mac.c:638 suspicious rcu_dereference_check() usage!
>
> 	other info that might help us debug this:
>
> 	rcu_scheduler_active = 2, debug_locks = 1
> 	no locks held by swapper/0/0.
> 	...
> 	Call trace:
> 	...
> 	 lockdep_rcu_suspicious+0x16c/0x22c
> 	 ath11k_mac_get_ar_by_pdev_id+0x194/0x1b0 [ath11k]
> 	 ath11k_wmi_tlv_op_rx+0xa84/0x2c1c [ath11k]
> 	 ath11k_htc_rx_completion_handler+0x388/0x510 [ath11k]
>
> Mark the code in question as an RCU read-side critical section to avoid
> any potential use-after-free issues.
>
> Fixes: a41d10348b01 ("ath11k: add thermal sensor device support")
> Cc: stable@vger.kernel.org      # 5.7
> Signed-off-by: Johan Hovold <johan+linaro@kernel.org>

On what hardware and firmware version did you test this? As there's so
many different combos we use Tested-on tag to provide that information
in the commit message:

https://wireless.wiki.kernel.org/en/users/drivers/ath11k/submittingpatches#tested-on_tag

I can add that if you let me know what you used.

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Re: [PATCH v2 1/2] wifi: ath11k: fix temperature event locking

[Johan Hovold]

On Tue, Oct 24, 2023 at 04:59:35PM +0300, Kalle Valo wrote:
> Johan Hovold <johan+linaro@kernel.org> writes:
> 
> > The ath11k active pdevs are protected by RCU but the temperature event
> > handling code calling ath11k_mac_get_ar_by_pdev_id() was not marked as a
> > read-side critical section as reported by RCU lockdep:

> On what hardware and firmware version did you test this? As there's so
> many different combos we use Tested-on tag to provide that information
> in the commit message:
> 
> https://wireless.wiki.kernel.org/en/users/drivers/ath11k/submittingpatches#tested-on_tag
> 
> I can add that if you let me know what you used.

I hit this on the Lenovo Thinkpad X13s and I guess the tag should be:

Tested-on: QCNFA765 hw2.1 WLAN.HSP.1.1-03125-QCAHSPSWPL_V1_V2_SILICONZ_LITE-3.6510.23

Note that I've only been able to test the ath11k fixes (not the
corresponding ath12k) and I only tested this particular patch fully
(e.g. since I didn't trigger any radar events).

Johan

Re: [PATCH v2 1/2] wifi: ath11k: fix temperature event locking

[Kalle Valo]

Johan Hovold <johan@kernel.org> writes:

> On Tue, Oct 24, 2023 at 04:59:35PM +0300, Kalle Valo wrote:
>> Johan Hovold <johan+linaro@kernel.org> writes:
>> 
>> > The ath11k active pdevs are protected by RCU but the temperature event
>> > handling code calling ath11k_mac_get_ar_by_pdev_id() was not marked as a
>> > read-side critical section as reported by RCU lockdep:
>
>> On what hardware and firmware version did you test this? As there's so
>> many different combos we use Tested-on tag to provide that information
>> in the commit message:
>> 
>> https://wireless.wiki.kernel.org/en/users/drivers/ath11k/submittingpatches#tested-on_tag
>> 
>> I can add that if you let me know what you used.
>
> I hit this on the Lenovo Thinkpad X13s and I guess the tag should be:
>
> Tested-on: QCNFA765 hw2.1 WLAN.HSP.1.1-03125-QCAHSPSWPL_V1_V2_SILICONZ_LITE-3.6510.23

From ath11k point of view QCNFA765 is WCN6855 so I used this one:

Tested-on: WCN6855 hw2.1 PCI WLAN.HSP.1.1-03125-QCAHSPSWPL_V1_V2_SILICONZ_LITE-3.6510.23

> Note that I've only been able to test the ath11k fixes (not the
> corresponding ath12k) and I only tested this particular patch fully

Thanks, I added Tested-on to this patch 1 and for the rest I added
"compile tested only".

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Re: [PATCH v2 1/2] wifi: ath11k: fix temperature event locking

[Johan Hovold]

On Wed, Oct 25, 2023 at 12:51:10PM +0300, Kalle Valo wrote:
> Johan Hovold <johan@kernel.org> writes:

> > I hit this on the Lenovo Thinkpad X13s and I guess the tag should be:
> >
> > Tested-on: QCNFA765 hw2.1 WLAN.HSP.1.1-03125-QCAHSPSWPL_V1_V2_SILICONZ_LITE-3.6510.23
> 
> From ath11k point of view QCNFA765 is WCN6855 so I used this one:
> 
> Tested-on: WCN6855 hw2.1 PCI WLAN.HSP.1.1-03125-QCAHSPSWPL_V1_V2_SILICONZ_LITE-3.6510.23
> 
> > Note that I've only been able to test the ath11k fixes (not the
> > corresponding ath12k) and I only tested this particular patch fully
> 
> Thanks, I added Tested-on to this patch 1 and for the rest I added
> "compile tested only".

Thanks for fixing that, I'll try to remember the Tested-on tag next
time.

Johan

Re: [PATCH v2 1/2] wifi: ath11k: fix temperature event locking

[Kalle Valo]

Johan Hovold <johan+linaro@kernel.org> wrote:

> The ath11k active pdevs are protected by RCU but the temperature event
> handling code calling ath11k_mac_get_ar_by_pdev_id() was not marked as a
> read-side critical section as reported by RCU lockdep:
> 
>         =============================
>         WARNING: suspicious RCU usage
>         6.6.0-rc6 #7 Not tainted
>         -----------------------------
>         drivers/net/wireless/ath/ath11k/mac.c:638 suspicious rcu_dereference_check() usage!
> 
>         other info that might help us debug this:
> 
>         rcu_scheduler_active = 2, debug_locks = 1
>         no locks held by swapper/0/0.
>         ...
>         Call trace:
>         ...
>          lockdep_rcu_suspicious+0x16c/0x22c
>          ath11k_mac_get_ar_by_pdev_id+0x194/0x1b0 [ath11k]
>          ath11k_wmi_tlv_op_rx+0xa84/0x2c1c [ath11k]
>          ath11k_htc_rx_completion_handler+0x388/0x510 [ath11k]
> 
> Mark the code in question as an RCU read-side critical section to avoid
> any potential use-after-free issues.
> 
> Tested-on: WCN6855 hw2.1 PCI WLAN.HSP.1.1-03125-QCAHSPSWPL_V1_V2_SILICONZ_LITE-3.6510.23
> 
> Fixes: a41d10348b01 ("ath11k: add thermal sensor device support")
> Cc: stable@vger.kernel.org      # 5.7
> Signed-off-by: Johan Hovold <johan+linaro@kernel.org>
> Acked-by: Jeff Johnson <quic_jjohnson@quicinc.com>
> Signed-off-by: Kalle Valo <quic_kvalo@quicinc.com>

2 patches applied to ath-next branch of ath.git, thanks.

1a5352a81b47 wifi: ath11k: fix temperature event locking
3b6c14833165 wifi: ath11k: fix dfs radar event locking

-- 
https://patchwork.kernel.org/project/linux-wireless/patch/20231019153115.26401-2-johan+linaro@kernel.org/

https://wireless.wiki.kernel.org/en/developers/documentation/submittingpatches

[PATCH v2 2/2] wifi: ath11k: fix dfs radar event locking

[Johan Hovold]

The ath11k active pdevs are protected by RCU but the DFS radar event
handling code calling ath11k_mac_get_ar_by_pdev_id() was not marked as a
read-side critical section.

Mark the code in question as an RCU read-side critical section to avoid
any potential use-after-free issues.

Fixes: d5c65159f289 ("ath11k: driver for Qualcomm IEEE 802.11ax devices")
Cc: stable@vger.kernel.org      # 5.6
Acked-by: Jeff Johnson <quic_jjohnson@quicinc.com>
Signed-off-by: Johan Hovold <johan+linaro@kernel.org>
---
 drivers/net/wireless/ath/ath11k/wmi.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/net/wireless/ath/ath11k/wmi.c b/drivers/net/wireless/ath/ath11k/wmi.c
index da1582b8dc30..f0eac6cb84fd 100644
--- a/drivers/net/wireless/ath/ath11k/wmi.c
+++ b/drivers/net/wireless/ath/ath11k/wmi.c
@@ -8337,6 +8337,8 @@ ath11k_wmi_pdev_dfs_radar_detected_event(struct ath11k_base *ab, struct sk_buff
 		   ev->detector_id, ev->segment_id, ev->timestamp, ev->is_chirp,
 		   ev->freq_offset, ev->sidx);
 
+	rcu_read_lock();
+
 	ar = ath11k_mac_get_ar_by_pdev_id(ab, ev->pdev_id);
 
 	if (!ar) {
@@ -8354,6 +8356,8 @@ ath11k_wmi_pdev_dfs_radar_detected_event(struct ath11k_base *ab, struct sk_buff
 		ieee80211_radar_detected(ar->hw);
 
 exit:
+	rcu_read_unlock();
+
 	kfree(tb);
 }
 
-- 
2.41.0

Re: [PATCH v2 0/2] wifi: ath11k: fix event locking

[Kalle Valo]

Johan Hovold <johan+linaro@kernel.org> writes:

> RCU lockdep reported suspicious RCU usage when accessing the temperature
> sensor. Inspection revealed that the DFS radar event code was also
> missing the required RCU read-side critical section marking.
>
> Johan
>
>
> Changes in v2
>  - add the missing rcu_read_unlock() to an
>    ath11k_wmi_pdev_temperature_event() error path as noticed by Jeff
>
>
> Johan Hovold (2):
>   wifi: ath11k: fix temperature event locking
>   wifi: ath11k: fix dfs radar event locking

Thanks for the fixes. I really like using lockdep_assert_held() to
document if a function requires some lock held, is there anything
similar for RCU?

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Re: [PATCH v2 0/2] wifi: ath11k: fix event locking

[Johan Hovold]

On Tue, Oct 24, 2023 at 05:07:38PM +0300, Kalle Valo wrote:
> Johan Hovold <johan+linaro@kernel.org> writes:
> 
> > RCU lockdep reported suspicious RCU usage when accessing the temperature
> > sensor. Inspection revealed that the DFS radar event code was also
> > missing the required RCU read-side critical section marking.
> >
> > Johan
> >
> >
> > Changes in v2
> >  - add the missing rcu_read_unlock() to an
> >    ath11k_wmi_pdev_temperature_event() error path as noticed by Jeff
> >
> >
> > Johan Hovold (2):
> >   wifi: ath11k: fix temperature event locking
> >   wifi: ath11k: fix dfs radar event locking
> 
> Thanks for the fixes. I really like using lockdep_assert_held() to
> document if a function requires some lock held, is there anything
> similar for RCU?

Not really, but the checking is instead built into the primitives like
rcu_dereference() and enabled whenever CONFIG_PROVE_RCU is set.

For some special cases, we have open-coded checks like:

	RCU_LOCKDEP_WARN(!rcu_read_lock_held());

which similarly depend on CONFIG_PROVE_RCU or simply

	WARN_ON_ONCE(!rcu_read_lock_held());

Johan

ath11k: checking RCU usage

[Kalle Valo]

(old discussion, changing title)

Johan Hovold <johan@kernel.org> writes:

> On Tue, Oct 24, 2023 at 05:07:38PM +0300, Kalle Valo wrote:
>
>> Johan Hovold <johan+linaro@kernel.org> writes:
>> 
>> > RCU lockdep reported suspicious RCU usage when accessing the temperature
>> > sensor. Inspection revealed that the DFS radar event code was also
>> > missing the required RCU read-side critical section marking.
>> >
>> > Johan
>> >
>> >
>> > Changes in v2
>> >  - add the missing rcu_read_unlock() to an
>> >    ath11k_wmi_pdev_temperature_event() error path as noticed by Jeff
>> >
>> >
>> > Johan Hovold (2):
>> >   wifi: ath11k: fix temperature event locking
>> >   wifi: ath11k: fix dfs radar event locking
>> 
>> Thanks for the fixes. I really like using lockdep_assert_held() to
>> document if a function requires some lock held, is there anything
>> similar for RCU?
>
> Not really, but the checking is instead built into the primitives like
> rcu_dereference() and enabled whenever CONFIG_PROVE_RCU is set.
>
> For some special cases, we have open-coded checks like:
>
> 	RCU_LOCKDEP_WARN(!rcu_read_lock_held());
>
> which similarly depend on CONFIG_PROVE_RCU or simply
>
> 	WARN_ON_ONCE(!rcu_read_lock_held());

I just found out that sparse has __must_hold():

https://lore.kernel.org/linux-wireless/87sf31hhfp.fsf@kernel.org/

That looks promising, should we start using that in ath11k and ath12k to
check our RCU usage?

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Re: ath11k: checking RCU usage

[Johan Hovold]

Hi Kalle,

On Sat, Jan 13, 2024 at 12:26:53PM +0200, Kalle Valo wrote:
> (old discussion, changing title)
> 
> Johan Hovold <johan@kernel.org> writes:
> 
> > On Tue, Oct 24, 2023 at 05:07:38PM +0300, Kalle Valo wrote:

> >> Thanks for the fixes. I really like using lockdep_assert_held() to
> >> document if a function requires some lock held, is there anything
> >> similar for RCU?
> >
> > Not really, but the checking is instead built into the primitives like
> > rcu_dereference() and enabled whenever CONFIG_PROVE_RCU is set.
> >
> > For some special cases, we have open-coded checks like:
> >
> > 	RCU_LOCKDEP_WARN(!rcu_read_lock_held());
> >
> > which similarly depend on CONFIG_PROVE_RCU or simply
> >
> > 	WARN_ON_ONCE(!rcu_read_lock_held());
> 
> I just found out that sparse has __must_hold():
> 
> https://lore.kernel.org/linux-wireless/87sf31hhfp.fsf@kernel.org/
> 
> That looks promising, should we start using that in ath11k and ath12k to
> check our RCU usage?

I see that Johannes already commented on this in the thread above.

I'm pretty sure smatch can't be used for this.

Johan

Re: ath11k: checking RCU usage

[Johan Hovold]

On Mon, Jan 22, 2024 at 02:10:17PM +0100, Johan Hovold wrote:
> On Sat, Jan 13, 2024 at 12:26:53PM +0200, Kalle Valo wrote:

> > I just found out that sparse has __must_hold():
> > 
> > https://lore.kernel.org/linux-wireless/87sf31hhfp.fsf@kernel.org/
> > 
> > That looks promising, should we start using that in ath11k and ath12k to
> > check our RCU usage?
> 
> I see that Johannes already commented on this in the thread above.
> 
> I'm pretty sure smatch can't be used for this.

I meant "sparse"...

Johan

Re: ath11k: checking RCU usage

[Kalle Valo]

Johan Hovold <johan@kernel.org> writes:

> On Mon, Jan 22, 2024 at 02:10:17PM +0100, Johan Hovold wrote:
>> On Sat, Jan 13, 2024 at 12:26:53PM +0200, Kalle Valo wrote:
>
>> > I just found out that sparse has __must_hold():
>> > 
>> > https://lore.kernel.org/linux-wireless/87sf31hhfp.fsf@kernel.org/
>> > 
>> > That looks promising, should we start using that in ath11k and ath12k to
>> > check our RCU usage?
>> 
>> I see that Johannes already commented on this in the thread above.
>> 
>> I'm pretty sure smatch can't be used for this.
>
> I meant "sparse"...

Yeah, that was a disappointment. I should have tested it first :)

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