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From:   Bruno Thomsen <bruno.thomsen@gmail.com>
Date:   Mon, 8 Mar 2021 09:50:26 +0100
Message-ID: <CAH+2xPC0sbqvsiBgsemHxrmE=JgnuOK6mzJ6pQ_G-ihqswAvPQ@mail.gmail.com>
Subject: Re: usb: cdc-acm: BUG kmalloc-128 Poison overwritten
To:     Oliver Neukum <oneukum@suse.com>
Cc:     linux-usb@vger.kernel.org,
        "moderated list:ARM/FREESCALE IMX / MXC ARM ARCHITECTURE" 
        <linux-arm-kernel@lists.infradead.org>,
        open list <linux-kernel@vger.kernel.org>,
        Bruno Thomsen <bth@kamstrup.com>,
        Lars Alex Pedersen <laa@kamstrup.com>
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Den fre. 26. feb. 2021 kl. 15.14 skrev Bruno Thomsen <bruno.thomsen@gmail.com>:
>
> Den tor. 25. feb. 2021 kl. 10.57 skrev Oliver Neukum <oneukum@suse.com>:
> >
> > Am Mittwoch, den 24.02.2021, 16:21 +0100 schrieb Bruno Thomsen:
> >
> > Hi,
> >
> > > No, this is not a regression from 5.10. It seems that many attempts to
> > > fix cdc-acm in the 5.x kernel series have failed to fix the root cause of
> > > these oops. I have not seen this on 4.14 and 4.19, but I have observed
> > > it on at least 5.3 and newer kernels in slight variations.
> > > I guess this is because cdc-acm is very common in the embedded
> > > ARM world and rarely used on servers or laptops. Combined with
> > > ARM devices still commonly use 4.x LTS kernels. Not sure if
> > > hardening options on the kernel has increased change of reproducing
> > > oops.
> >
> > OK, so this is not an additional problem.
> > According to your logs, an URB that should have been killed wasn't.
>
> Thanks for looking into this bug rapport.
>
> > > I am ready to test new patches and will continue to report oops
> >
> > Could you test the attached patches?
>
> Yes, I am already running tests on the patches.
> I have not seen any oops yet and it seems the USB cdc-acm driver is still
> working as intended.
>
> The only notable trace I have seen is this new error from the cdc-acm driver
> but everything kept on working.
> kernel: cdc_acm 1-1.1:1.7: acm_start_wb - usb_submit_urb(write bulk) failed: -19
>
> Other then that I see this common error (should probably be a warning) during
> device enumeration:
> kernel: cdc_acm 1-1.2:1.0: failed to set dtr/rts
>
> I will post an update next week when the patches have survived some
> more runtime.

Tested-by: Bruno Thomsen <bruno.thomsen@gmail.com>

I have not observed any oops with patches applied. Patches have seen
more than 10 weeks of runtime testing across multiple devices.

/Bruno