Re: [PATCH v2 1/4] usb: typec: ucsi: Fix null deref in trace

From: Jameson Thies <jthies@google.com>
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>,
	"Uwe Kleine-König" <u.kleine-koenig@pengutronix.de>
Subject: Re: [PATCH v2 1/4] usb: typec: ucsi: Fix null deref in trace
Date: Mon, 29 Apr 2024 17:43:16 -0700	[thread overview]
Message-ID: <CAMFSARfOYWy0a_iZyuh9e8++xHdAYXcs2pT1_yJaJ60tHR17xQ@mail.gmail.com> (raw)
In-Reply-To: <2024042547-shimmy-guileless-c7f2@gregkh>

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