From: Johan Hovold <johan@kernel.org>
To: Oliver Neukum <oneukum@suse.com>
Cc: Johan Hovold <johan@kernel.org>, Erik Slagter <erik@slagter.name>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
linux-usb@vger.kernel.org,
Daniel Caujolle-Bert <f1rmb.daniel@gmail.com>
Subject: Re: [PATCH v2 4/4] USB: cdc-acm: clean up no-union-descriptor handling
Date: Mon, 21 Sep 2020 17:16:05 +0200 [thread overview]
Message-ID: <20200921151605.GY24441@localhost> (raw)
In-Reply-To: <1600700674.2424.105.camel@suse.com>
On Mon, Sep 21, 2020 at 05:04:34PM +0200, Oliver Neukum wrote:
> Am Montag, den 21.09.2020, 16:28 +0200 schrieb Johan Hovold:
> > On Mon, Sep 21, 2020 at 04:16:56PM +0200, Oliver Neukum wrote:
> > > Am Montag, den 21.09.2020, 15:59 +0200 schrieb Johan Hovold:
> > > > For interfaces that lack a union descriptor, probe for a
> > > > "combined-interface" before falling back to the call-management
> > > > descriptor instead of the other way round.
> > >
> > > Hi,
>
> Hi,
>
> > >
> > > the more I look at this the more it seems to me like the
> > > device that has the quirk does NOT have a collapsed interface
> > > but two interfaces and just a lack of a union descriptor.
> >
> > But then why name the quirk NO_DATA_INTERFACE if it has a data
>
> In hindsight that seems not the best name.
>
> > interface? By hardcoding the data-interface number to be the one and
> > only interface, you'd end up probing for a "combined" interface also
> > with a broken call-management descriptor.
>
> Well, by the changelog assuming a combined interface caused an oops.
> Thence I am forced to conclude that the davices _has_ a separate
> data interface, but no union descriptor.
No, the oops was probably due to the missing sanity check later added by
403dff4e2c94 ("USB: cdc-acm: check for valid interfaces").
With a broken call-management descriptor pointing to a non-existent
interface we'd oops before that commit.
> > Side note: I really think we should start mandating lsusb output to go
> > along with any patch for quirky devices.
>
> Good idea. Convince Greg.
Heh. I'm sure he can be convinced. :)
Johan
next prev parent reply other threads:[~2020-09-21 15:16 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-09-21 13:59 [PATCH v2 0/4] USB: cdc-acm: handle broken union descriptors Johan Hovold
2020-09-21 13:59 ` [PATCH v2 1/4] Revert "cdc-acm: hardening against malicious devices" Johan Hovold
2020-09-21 13:59 ` [PATCH v2 2/4] USB: cdc-acm: handle broken union descriptors Johan Hovold
2020-09-22 9:53 ` <Daniel Caujolle-Bert>
2020-09-21 13:59 ` [PATCH v2 3/4] USB: cdc-acm: use common data-class define Johan Hovold
2020-09-21 13:59 ` [PATCH v2 4/4] USB: cdc-acm: clean up no-union-descriptor handling Johan Hovold
2020-09-21 14:16 ` Oliver Neukum
2020-09-21 14:28 ` Johan Hovold
2020-09-21 15:04 ` Oliver Neukum
2020-09-21 15:16 ` Johan Hovold [this message]
2020-09-21 17:17 ` Oliver Neukum
2020-09-22 7:05 ` Johan Hovold
2020-09-22 10:40 ` Oliver Neukum
2020-09-22 10:54 ` Johan Hovold
2020-09-22 11:41 ` Oliver Neukum
2020-09-22 11:47 ` Johan Hovold
2020-09-21 14:21 ` [PATCH v2 0/4] USB: cdc-acm: handle broken union descriptors <Daniel Caujolle-Bert>
2020-09-21 16:19 ` <Daniel Caujolle-Bert>
2020-09-22 7:08 ` Johan Hovold
2020-09-22 9:56 ` <Daniel Caujolle-Bert>
2020-09-22 10:07 ` Johan Hovold
2020-09-22 12:10 ` Oliver Neukum
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20200921151605.GY24441@localhost \
--to=johan@kernel.org \
--cc=erik@slagter.name \
--cc=f1rmb.daniel@gmail.com \
--cc=gregkh@linuxfoundation.org \
--cc=linux-usb@vger.kernel.org \
--cc=oneukum@suse.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.