2020-06-22 13:40:10

by Reto Schneider

Subject: [PATCH 1/3] rtl8192cu: Fix deadlock

Prevent code from calling itself indirectly, causing the driver to hang
and consume 100% CPU.

Without this fix, the following script can bring down a single CPU
system:
```
while true; do
rmmod rtl8192cu
modprobe rtl8192cu
done
```

Signed-off-by: Reto Schneider <[email protected]>
---
drivers/net/wireless/realtek/rtlwifi/usb.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/net/wireless/realtek/rtlwifi/usb.c b/drivers/net/wireless/realtek/rtlwifi/usb.c
index c66c6dc00378..d3bbfc0171f6 100644
--- a/drivers/net/wireless/realtek/rtlwifi/usb.c
+++ b/drivers/net/wireless/realtek/rtlwifi/usb.c
@@ -680,8 +680,10 @@ static void _rtl_usb_cleanup_rx(struct ieee80211_hw *hw)
tasklet_kill(&rtlusb->rx_work_tasklet);
cancel_work_sync(&rtlpriv->works.lps_change_work);

- flush_workqueue(rtlpriv->works.rtl_wq);
- destroy_workqueue(rtlpriv->works.rtl_wq);
+ if (rtlpriv->works.rtl_wq) {
+ destroy_workqueue(rtlpriv->works.rtl_wq);
+ rtlpriv->works.rtl_wq = NULL;
+ }

skb_queue_purge(&rtlusb->rx_queue);

--
2.20.1

2020-06-22 18:02:22

by Larry Finger

Subject: Re: [PATCH 1/3] rtl8192cu: Fix deadlock

On 6/22/20 8:21 AM, Reto Schneider wrote:
> Prevent code from calling itself indirectly, causing the driver to hang
> and consume 100% CPU.
>
> Without this fix, the following script can bring down a single CPU
> system:
> ```
> while true; do
> rmmod rtl8192cu
> modprobe rtl8192cu
> done
> ```
>
> Signed-off-by: Reto Schneider <[email protected]>

I have one small comment. Patches for the rtlwifi family of drivers have patch
subjects of the form [PATCH] rtlwifi: rtl8192cu: blah blah. I'll let Kalle
decide if he wants ignore my comment, manually change the subjects, or request a
V2. Otherwise all 3 patches are OK.

ACKed-by: Larry Finger <[email protected]>

Larry

2020-06-23 09:23:54

by Kalle Valo

Subject: Re: [PATCH 1/3] rtl8192cu: Fix deadlock

Larry Finger <[email protected]> writes:

> On 6/22/20 8:21 AM, Reto Schneider wrote:
>> Prevent code from calling itself indirectly, causing the driver to hang
>> and consume 100% CPU.
>>
>> Without this fix, the following script can bring down a single CPU
>> system:
>> ```
>> while true; do
>> rmmod rtl8192cu
>> modprobe rtl8192cu
>> done
>> ```
>>
>> Signed-off-by: Reto Schneider <[email protected]>
>
> I have one small comment. Patches for the rtlwifi family of drivers
> have patch subjects of the form [PATCH] rtlwifi: rtl8192cu: blah blah.
> I'll let Kalle decide if he wants ignore my comment, manually change
> the subjects, or request a V2. Otherwise all 3 patches are OK.

I can fix the titles during commit.

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

2020-07-15 11:26:07

by Kalle Valo

Subject: Re: [PATCH 1/3] rtlwifi: rtl8192cu: Fix deadlock

Reto Schneider <[email protected]> wrote:

> Prevent code from calling itself indirectly, causing the driver to hang
> and consume 100% CPU.
>
> Without this fix, the following script can bring down a single CPU
> system:
> ```
> while true; do
> rmmod rtl8192cu
> modprobe rtl8192cu
> done
> ```
>
> Signed-off-by: Reto Schneider <[email protected]>
> ACKed-by: Larry Finger <[email protected]>

3 patches applied to wireless-drivers-next.git, thanks.

ec89032cd148 rtlwifi: rtl8192cu: Fix deadlock
03128643eb54 rtlwifi: rtl8192cu: Prevent leaking urb
a7f7c15e945a rtlwifi: rtl8192cu: Free ieee80211_hw if probing fails

--
https://patchwork.kernel.org/patch/11617759/

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