netdev - RE: [PATCH net 1/3] dpll: fix pin dump crash after module unbind

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Message-ID: <DM6PR11MB46579E6553D7C7DF5B37BD4C9BAFA@DM6PR11MB4657.namprd11.prod.outlook.com>
Date: Thu, 9 Nov 2023 16:33:35 +0000
From: "Kubalewski, Arkadiusz" <arkadiusz.kubalewski@...el.com>
To: Jiri Pirko <jiri@...nulli.us>
CC: "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
	"vadim.fedorenko@...ux.dev" <vadim.fedorenko@...ux.dev>, "Michalik, Michal"
	<michal.michalik@...el.com>, "Olech, Milena" <milena.olech@...el.com>,
	"pabeni@...hat.com" <pabeni@...hat.com>, "kuba@...nel.org" <kuba@...nel.org>
Subject: RE: [PATCH net 1/3] dpll: fix pin dump crash after module unbind

>From: Jiri Pirko <jiri@...nulli.us>
>Sent: Thursday, November 9, 2023 2:18 PM
>
>Thu, Nov 09, 2023 at 10:49:49AM CET, arkadiusz.kubalewski@...el.com wrote:
>>>From: Jiri Pirko <jiri@...nulli.us>
>>>Sent: Wednesday, November 8, 2023 4:09 PM
>>>
>>>Wed, Nov 08, 2023 at 11:32:24AM CET, arkadiusz.kubalewski@...el.com
>>>wrote:
>>>>Disallow dump of unregistered parent pins, it is possible when parent
>>>>pin and dpll device registerer kernel module instance unbinds, and
>>>>other kernel module instances of the same dpll device have pins
>>>>registered with the parent pin. The user can invoke a pin-dump but as
>>>>the parent was unregistered, thus shall not be accessed by the
>>>>userspace, prevent that by checking if parent pin is still registered.
>>>>
>>>>Fixes: 9d71b54b65b1 ("dpll: netlink: Add DPLL framework base functions")
>>>>Signed-off-by: Arkadiusz Kubalewski <arkadiusz.kubalewski@...el.com>
>>>>---
>>>> drivers/dpll/dpll_netlink.c | 7 +++++++
>>>> 1 file changed, 7 insertions(+)
>>>>
>>>>diff --git a/drivers/dpll/dpll_netlink.c b/drivers/dpll/dpll_netlink.c
>>>>index a6dc3997bf5c..93fc6c4b8a78 100644
>>>>--- a/drivers/dpll/dpll_netlink.c
>>>>+++ b/drivers/dpll/dpll_netlink.c
>>>>@@ -328,6 +328,13 @@ dpll_msg_add_pin_parents(struct sk_buff *msg,
>>>>        struct dpll_pin *pin,
>>>> 		void *parent_priv;
>>>>
>>>> 		ppin = ref->pin;
>>>>+		/*
>>>>+		 * dump parent only if it is registered, thus prevent crash on
>>>>+		 * pin dump called when driver which registered the pin unbinds
>>>>+		 * and different instance registered pin on that parent pin
>>>
>>>Read this sentence like 10 times, still don't get what you mean.
>>>Shouldn't comments be easy to understand?
>>>
>>
>>Hi,
>>
>>Hmm, wondering isn't it better to remove this comment at all?
>>If you think it is needed I will rephrase it somehow..
>
>I don't know if it is needed as I don't understand it :)
>Just remove it.
>

Sure, will do.

Thank you!
Arkadiusz

>
>>
>>Thank you!
>>Arkadiusz
>>
>>>
>>>>+		 */
>>>>+		if (!xa_get_mark(&dpll_pin_xa, ppin->id, DPLL_REGISTERED))
>>>>+			continue;
>>>> 		parent_priv = dpll_pin_on_dpll_priv(dpll_ref->dpll, ppin);
>>>> 		ret = ops->state_on_pin_get(pin,
>>>> 					    dpll_pin_on_pin_priv(ppin, pin),
>>>>--
>>>>2.38.1
>>>>
>>