linux-kernel - [PATCH 1/3] gpio: take the SRCU read lock in gpiod

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <20240213093108.13922-2-brgl@bgdev.pl>
Date: Tue, 13 Feb 2024 10:31:06 +0100
From: Bartosz Golaszewski <brgl@...ev.pl>
To: Linus Walleij <linus.walleij@...aro.org>,
	Kent Gibson <warthog618@...il.com>,
	Alex Elder <elder@...aro.org>,
	Geert Uytterhoeven <geert+renesas@...der.be>,
	"Paul E . McKenney" <paulmck@...nel.org>,
	Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
	Wolfram Sang <wsa@...-dreams.de>
Cc: linux-gpio@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	Bartosz Golaszewski <bartosz.golaszewski@...aro.org>,
	kernel test robot <oliver.sang@...el.com>
Subject: [PATCH 1/3] gpio: take the SRCU read lock in gpiod_hog()

From: Bartosz Golaszewski <bartosz.golaszewski@...aro.org>

gpiod_hog() may be called without the gpio_device SRCU read lock taken
so we need to do it here as well. It's alright if someone else is
already holding the lock as SRCU read critical sections can be nested.

Fixes: d83cee3d2bb1 ("gpio: protect the pointer to gpio_chip in gpio_device with SRCU")
Reported-by: kernel test robot <oliver.sang@...el.com>
Closes: https://lore.kernel.org/oe-lkp/202402122234.d85cca9b-lkp@intel.com
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@...aro.org>
---
 drivers/gpio/gpiolib.c | 11 +++++++----
 1 file changed, 7 insertions(+), 4 deletions(-)

diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c
index 82811d9a4477..c1391a9a0af6 100644
--- a/drivers/gpio/gpiolib.c
+++ b/drivers/gpio/gpiolib.c
@@ -4492,24 +4492,27 @@ EXPORT_SYMBOL_GPL(gpiod_get_index_optional);
 int gpiod_hog(struct gpio_desc *desc, const char *name,
 	      unsigned long lflags, enum gpiod_flags dflags)
 {
-	struct gpio_chip *gc;
+	struct gpio_device *gdev = desc->gdev;
 	struct gpio_desc *local_desc;
 	int hwnum;
 	int ret;
 
+	CLASS(gpio_chip_guard, guard)(desc);
+	if (!guard.gc)
+		return -ENODEV;
+
 	if (test_and_set_bit(FLAG_IS_HOGGED, &desc->flags))
 		return 0;
 
-	gc = gpiod_to_chip(desc);
 	hwnum = gpio_chip_hwgpio(desc);
 
-	local_desc = gpiochip_request_own_desc(gc, hwnum, name,
+	local_desc = gpiochip_request_own_desc(guard.gc, hwnum, name,
 					       lflags, dflags);
 	if (IS_ERR(local_desc)) {
 		clear_bit(FLAG_IS_HOGGED, &desc->flags);
 		ret = PTR_ERR(local_desc);
 		pr_err("requesting hog GPIO %s (chip %s, offset %d) failed, %d\n",
-		       name, gc->label, hwnum, ret);
+		       name, gdev->label, hwnum, ret);
 		return ret;
 	}
 
-- 
2.40.1