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: Tue, 22 Sep 2020 12:54:46 +0200 [thread overview]
Message-ID: <20200922105446.GC24441@localhost> (raw)
In-Reply-To: <1600771242.6926.16.camel@suse.com>
On Tue, Sep 22, 2020 at 12:40:42PM +0200, Oliver Neukum wrote:
> Am Dienstag, den 22.09.2020, 09:05 +0200 schrieb Johan Hovold:
>
> > The relevant commits are
> >
> > a2bfb4a346d2 ("USB: support for cdc-acm of single interface devices") (2009)
> > fd5054c169d2 ("USB: cdc_acm: Fix oops when Droids MuIn LCD is connected") (2011)
> > 403dff4e2c94 ("USB: cdc-acm: check for valid interfaces") (2014)
> >
> > Before Greg added the sanity checks in that last commit, a broken
> > call-management descriptor referring to a non-existent interface would
> > cause a NULL-pointer dereference.
>
> Yes.
>
> > The second commit, adding support for a specific device, didn't fix that
> > problem generally
>
> Yes
>
> > and only worked around it for one device by hardcoding
> > the data interface to match the control interface,
>
> How do you know. It hardcoded the data interface. That it matches
> the control interface is a guess.
No, see below.
> > thereby falling back
> > to the "combined-interface" probing you added in that first commit.
>
> How do you know? They may or may not match.
Heh. Did you actually read the commit message?
"Add NO_DATA_INTERFACE quirk to tell the driver that "control"
and "data" interfaces are not separated for this device, which
prevents dereferencing a null pointer in the device probe
code."
Convinced yet?
Johan
next prev parent reply other threads:[~2020-09-22 10:54 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
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 [this message]
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
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