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

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Message-ID: <DM6PR11MB46576110B45D806064F437C49BAFA@DM6PR11MB4657.namprd11.prod.outlook.com>
Date: Thu, 9 Nov 2023 09:49:49 +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: 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..

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
>>