Re: brcmfmac: Unable to handle kernel paging request at virtual address 726f6674616cd8

[Stefan Wahren <stefan.wahren@i2se.com>]

Hi Arend,

> Arend van Spriel <arend.vanspriel@broadcom.com> hat am 22. November 2017 um 19:23 geschrieben:
> 
> 
> On 22-11-17 17:20, Stefan Wahren wrote:
> > Hi,
> > 
> >> Stefan Wahren <stefan.wahren@i2se.com> hat am 12. November 2017 um 17:50 geschrieben:
> >>
> >>
> >> Hi,
> >> i discovered a random oops during probe of brcmfmac on Raspberry Pi 3 in yesterdays kernelci run for net-next [1]. I need to point out there is no DT entry for the wifi chip on Raspberry Pi 3 in the lack of a driver for the necessary GPIO expander. So the "HT Avail timeout" is expected.
> >>
> >> I was also able to trigger this oops by calling "modprobe brcmfmac" on my Raspberry Pi 3 with latest linux-next.
> >>
> >> Any help to fix this is appreciated.
> >>
> >> [1] - https://storage.kernelci.org/net-next/master/v4.14-rc8-2221-ga8a6f1e4ea78/arm64/defconfig+kselftest/lab-baylibre/boot-bcm2837-rpi-3-b.txt
> >>
> > 
> > the issue still persists in linux-next-20171122:
> > 
> ...
> 
> seems like a use-after-free. We do a device_release_driver() twice. Once 
> for sdio func #1 and for sdio func #2. This was introduced by:
> 
> commit 7a51461fc2da82a6c565a3ee65c41c197f28225d
> Author: Arend Van Spriel <arend.vanspriel@broadcom.com>
> Date:   Mon Jun 12 12:47:34 2017 +0100
> 
>      brcmfmac: unbind all devices upon failure in firmware callback
> 
> What we do is:
> 
>          device_release_driver(dev);
>          device_release_driver(&sdiodev->func[2]->dev);
> 
> with the assumption that dev == &sdiodev->func[1]->dev. I wonder if that 
> is always true. The error print did not make it in your log. Maybe we 
> should make it explicit here (see below).

i tried it, but the issue still occurs.

Maybe this is helpful but this issue doesn't happend everytime. Sometimes i need 2 attemps via unloading/loading.

> 
> Regards,
> Arend
> ---
> 
> diff --git a/drivers/net/wireless/broadcom/brcm80211/brcmfmac/sdio.c 
> b/drivers/net/wireless/broadcom/brcm80211/brcmfmac/sdio.c
> index 613caca..0fda9a4 100644
> --- a/drivers/net/wireless/broadcom/brcm80211/brcmfmac/sdio.c
> +++ b/drivers/net/wireless/broadcom/brcm80211/brcmfmac/sdio.c
> @@ -4096,7 +4096,7 @@ static void brcmf_sdio_firmware_callback(struct 
> device *dev, int err,
>          sdio_release_host(sdiodev->func[1]);
>   fail:
>          brcmf_dbg(TRACE, "failed: dev=%s, err=%d\n", dev_name(dev), err);
> -       device_release_driver(dev);
> +       device_release_driver(&sdiodev->func[1]->dev);
>          device_release_driver(&sdiodev->func[2]->dev);
>   }
>