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Date:   Sun, 05 May 2019 09:55:19 -0700 (PDT)
Message-Id: <20190505.095519.1938967372701152762.davem@davemloft.net>
To:     pebolle@tiscali.nl
Cc:     netdev@vger.kernel.org, bigeasy@linutronix.de,
        gigaset307x-common@lists.sourceforge.net,
        linux-kernel@vger.kernel.org, arnd@arndb.de
Subject: Re: [PATCH] isdn: bas_gigaset: use usb_fill_int_urb() properly
From:   David Miller <davem@davemloft.net>
In-Reply-To: <20190501211903.14806-1-pebolle@tiscali.nl>
References: <20190501211903.14806-1-pebolle@tiscali.nl>
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From: Paul Bolle <pebolle@tiscali.nl>
Date: Wed,  1 May 2019 23:19:03 +0200

> The switch to make bas_gigaset use usb_fill_int_urb() - instead of
> filling that urb "by hand" - missed the subtle ordering of the previous
> code.
> 
> See, before the switch urb->dev was set to a member somewhere deep in a
> complicated structure and then supplied to usb_rcvisocpipe() and
> usb_sndisocpipe(). After that switch urb->dev wasn't set to anything
> specific before being supplied to those two macros. This triggers a
> nasty oops:
...
> No-one noticed because this Oops is apparently only triggered by setting
> up an ISDN data connection on a live ISDN line on a gigaset base (ie,
> the PBX that the gigaset driver support). Very few people do that
> running present day kernels.
> 
> Anyhow, a little code reorganization makes this problem go away, while
> avoiding the subtle ordering that was used in the past. So let's do
> that.
> 
> Fixes: 78c696c19578 ("isdn: gigaset: use usb_fill_int_urb()")
> Signed-off-by: Paul Bolle <pebolle@tiscali.nl>
> ---
> Arnd's ISDN cleanup hasn't yet hit net-next so this still uses
> drivers/isdn. If people prefer to apply this after Arnd has exiled
> gigaset into staging, I'll gladly respin. 

Applied to 'net', queued up for -stable, and I'll deal with the
merge conflict :-/ :-) :-)