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

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Date: Thu, 9 Nov 2023 14:18:09 +0100
From: Jiri Pirko <jiri@...nulli.us>
To: "Kubalewski, Arkadiusz" <arkadiusz.kubalewski@...el.com>
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

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.


>
>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
>>>
>