linux-kernel - Re: rtlwifi: rtl8192c_common: "BUG: KASAN: slab-out-of-bounds"

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Message-ID: <92f6dcb7-bbee-533a-7d49-21670286a3f3@lwfinger.net>
Date:   Sun, 5 Feb 2017 11:30:30 -0600
From:   Larry Finger <Larry.Finger@...inger.net>
To:     Dmitry Osipenko <digetx@...il.com>
Cc:     linux-wireless@...r.kernel.org,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: rtlwifi: rtl8192c_common: "BUG: KASAN: slab-out-of-bounds"

On 02/05/2017 05:34 AM, Dmitry Osipenko wrote:
> BTW, I have an issue with the 8192cu: WiFi stops to work after a while (3-15
> minutes) if I enable WMM QoS on the AP. There is nothing suspicious in KMSG,
> connection is up but no packets go in/out. I tried to enable debug messages in
> the driver, so when the WiFi stops to work I see that some "temperature/led"
> notify still going on in the driver, but nothing happens when I try to initiate
> a transfer (say to open a web page) - the log is silent, like the requests are
> getting stuck/dropped somewhere before reaching the driver. Is it a known issue?
> With the QoS disabled everything works hunky-dory, however I get 2x-4x faster
> download speed with QoS enabled (while it works.)
>
> I noticed that rtl92c_init_edca_param() isn't wired in the driver, so I suppose
> the QoS isn't implemented yet, right?
>
> If it is an expected behaviour, I think at least printing a warning message in
> the KMSG like "QoS unimplemented, you may expect problems" should be good enough
> to avoid confusion.

As you have already seen, I decided to defer the more invasive patch. When 
backporting to stable, the smaller the change the better.

I have no knowledge of the internals of the RTL8192CU chip. As a result, the 
kinds of changes I can make are limited. I do know that the chip does implement 
QoS. I also noticed that the set_qos() callback routine was very different in 
rtl8192ce than in rtl8192cu. Attached is an untested patch to make the CU 
routine look like the CE version. Please see if it makes a difference.

Driver rtl8192cu has never been maintained by Realtek, and it will likely be 
removed from the kernel in the next few cycles. As you are running a new kernel, 
I would recommend rtl8xxxu instead. That driver has high reliability, and the 
speed is improving. Your other option would be a driver offered by the vendor of 
your particular device. Realtek used to have these drivers on their web site, 
but they now seem to have been removed. If your vendor does not have a driver, 
http://www.edimax.com/edimax/mw/cufiles/files/download/Driver_Utility/transfer/Wireless/NIC/EW-7811Un/EW-7811Un_Linux_driver_v1.0.0.5.zip 
should work.

Larry

View attachment "rtl8192cu_add_qos.patch" of type "text/x-patch" (1004 bytes)