linux-kernel - [PATCH] usb: typec: Prevent memory leak in typec_register

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Message-ID: <c05e397c-5ed1-49d9-92a0-826f21fe2469@web.de>
Date: Fri, 28 Jun 2024 18:08:27 +0200
From: Markus Elfring <Markus.Elfring@....de>
To: linux-usb@...r.kernel.org, kernel-janitors@...r.kernel.org,
 Andy Shevchenko <andy.shevchenko@...il.com>,
 Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
 Günter Röck <linux@...ck-us.net>,
 Hans de Goede <hdegoede@...hat.com>,
 Heikki Krogerus <heikki.krogerus@...ux.intel.com>,
 Prashant Malani <pmalani@...omium.org>, Wen Yang <wenyang@...ux.alibaba.com>
Cc: LKML <linux-kernel@...r.kernel.org>,
 Jonathan Cameron <Jonathan.Cameron@...wei.com>,
 Julia Lawall <julia.lawall@...ia.fr>
Subject: [PATCH] usb: typec: Prevent memory leak in typec_register_port()

From: Markus Elfring <elfring@...rs.sourceforge.net>
Date: Fri, 28 Jun 2024 17:46:19 +0200

Memory is allocated for the data structure “typec_port” at the beginning
of this function implementation.
Unfortunately, it was not released in all subsequent error cases.

Thus apply scope-based resource management which became supported
for this programming interface by contributions of Peter Zijlstra
on 2023-05-26.
See also the commit 54da6a0924311c7cf5015533991e44fb8eb12773 ("locking:
Introduce __cleanup() based infrastructure").

* Use the attribute “__free(kfree)” accordingly.

* Reduce the scope for the local variable “port”.

Cc: stable@...r.kernel.org
Fixes: f31a8702cd36 ("usb: typec: Add retimer handle to port")
Fixes: a7cff92f0635 ("usb: typec: USB Power Delivery helpers for ports and partners")
Fixes: 5c388abefda0 ("usb: typec: fix use after free in typec_register_port()")
Fixes: ad772c39b2fb ("usb: typec: Copy everything from struct typec_capability during registration")
Fixes: cf6e06cddf29 ("usb: typec: Start using ERR_PTR")
Signed-off-by: Markus Elfring <elfring@...rs.sourceforge.net>
---

I guess that clarifications can become interesting also for backporting concerns
because of the proposed software transformation.


drivers/usb/typec/class.c | 9 +++------
 1 file changed, 3 insertions(+), 6 deletions(-)

diff --git a/drivers/usb/typec/class.c b/drivers/usb/typec/class.c
index 9262fcd4144f..97c0afd41e35 100644
--- a/drivers/usb/typec/class.c
+++ b/drivers/usb/typec/class.c
@@ -2372,19 +2372,16 @@ EXPORT_SYMBOL_GPL(typec_port_register_cable_ops);
 struct typec_port *typec_register_port(struct device *parent,
 				       const struct typec_capability *cap)
 {
-	struct typec_port *port;
 	int ret;
 	int id;

-	port = kzalloc(sizeof(*port), GFP_KERNEL);
+	struct typec_port *port __free(kfree) = kzalloc(sizeof(*port), GFP_KERNEL);
 	if (!port)
 		return ERR_PTR(-ENOMEM);

 	id = ida_alloc(&typec_index_ida, GFP_KERNEL);
-	if (id < 0) {
-		kfree(port);
+	if (id < 0)
 		return ERR_PTR(id);
-	}

 	switch (cap->type) {
 	case TYPEC_PORT_SRC:
@@ -2483,7 +2480,7 @@ struct typec_port *typec_register_port(struct device *parent,
 	if (ret)
 		dev_warn(&port->dev, "failed to create symlinks (%d)\n", ret);

-	return port;
+	return_ptr(port);
 }
 EXPORT_SYMBOL_GPL(typec_register_port);

--
2.45.2