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 <2024042547-shimmy-guileless-c7f2@gregkh>
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From: Jameson Thies <jthies@google.com>
Date: Mon, 29 Apr 2024 17:43:16 -0700
Message-ID: <CAMFSARfOYWy0a_iZyuh9e8++xHdAYXcs2pT1_yJaJ60tHR17xQ@mail.gmail.com>
Subject: Re: [PATCH v2 1/4] usb: typec: ucsi: Fix null deref in trace
To: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Markus Elfring <Markus.Elfring@web.de>, 
	Abhishek Pandit-Subedi <abhishekpandit@chromium.org>, linux-usb@vger.kernel.org, 
	kernel-janitors@vger.kernel.org, 
	Heikki Krogerus <heikki.krogerus@linux.intel.com>, LKML <linux-kernel@vger.kernel.org>, 
	Benson Leung <bleung@google.com>, Bjorn Andersson <andersson@kernel.org>, 
	Dmitry Baryshkov <dmitry.baryshkov@linaro.org>, Fabrice Gasnier <fabrice.gasnier@foss.st.com>, 
	Hans de Goede <hdegoede@redhat.com>, Neil Armstrong <neil.armstrong@linaro.org>, 
	Prashant Malani <pmalani@chromium.org>, Rajaram Regupathy <rajaram.regupathy@intel.com>, 
	Saranya Gopal <saranya.gopal@intel.com>, 
	=?UTF-8?Q?Uwe_Kleine=2DK=C3=B6nig?= <u.kleine-koenig@pengutronix.de>
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Hi Dmitry,
what are your thoughts on Abhishek's comment? I think we should
attempt to register the alternate mode when CONFIG_TYPEC_DP_ALTMODE is
not enabled. It would give us a more accurate representation of the
partner in user space. I understand your point about ignoring a
potential EOPNOTSUPP response from the non-stub function. What if we
leave ucsi.c alone, and replace the stub function's null return with a
call to typec_port_register_altmode(). That would register DP altmode
as an unsupported mode when CONFIG_TYPEC_DP_ALTMODE is not enabled,
and fix the null pointer dereference. But, it won't change behavior
when CONFIG_TYPEC_DP_ALTMODE is enabled.

Hi Markus,
thanks for your feedback. I'll update the commit message to say "null
pointer dereference" when I upload a v3 series.

Thanks,
Jameson