On Thu, Mar 11, 2021 at 06:41:41PM +0100, Greg Kroah-Hartman wrote:
The patch below does not apply to the 5.11-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.
------------------ original commit in Linus's tree ------------------
From cf25ef6b631c6fc6c0435fc91eba8734cca20511 Mon Sep 17 00:00:00 2001 From: Johan Hovold johan@kernel.org Date: Mon, 1 Mar 2021 10:05:19 +0100 Subject: [PATCH] gpio: fix gpio-device list corruption
Make sure to hold the gpio_lock when removing the gpio device from the gpio_devices list (when dropping the last reference) to avoid corrupting the list when there are concurrent accesses.
Fixes: ff2b13592299 ("gpio: make the gpiochip a real device") Cc: stable@vger.kernel.org # 4.6 Reviewed-by: Saravana Kannan saravanak@google.com Signed-off-by: Johan Hovold johan@kernel.org Signed-off-by: Bartosz Golaszewski bgolaszewski@baylibre.com
diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c index 6e0572515d02..4253837f870b 100644 --- a/drivers/gpio/gpiolib.c +++ b/drivers/gpio/gpiolib.c @@ -475,8 +475,12 @@ EXPORT_SYMBOL_GPL(gpiochip_line_is_valid); static void gpiodevice_release(struct device *dev) { struct gpio_device *gdev = container_of(dev, struct gpio_device, dev);
- unsigned long flags;
- spin_lock_irqsave(&gpio_lock, flags); list_del(&gdev->list);
- spin_unlock_irqrestore(&gpio_lock, flags);
- ida_free(&gpio_ida, gdev->id); kfree_const(gdev->label); kfree(gdev->descs);
Bah, that's because of a6112998ee45 ("gpio: fix NULL-deref-on-deregistration regression") which is strictly only needed in 5.12 even if it could be backported (the commit message might be a bit confusing though).
I should have reversed the order of these two.
Below is a backport to 5.11.
Johan
From 7599320f36bb5273844dfb749861a5361d8aa5b7 Mon Sep 17 00:00:00 2001
From: Johan Hovold johan@kernel.org Date: Mon, 1 Mar 2021 10:05:19 +0100 Subject: [PATCH] gpio: fix gpio-device list corruption
Make sure to hold the gpio_lock when removing the gpio device from the gpio_devices list (when dropping the last reference) to avoid corrupting the list when there are concurrent accesses.
Fixes: ff2b13592299 ("gpio: make the gpiochip a real device") Cc: stable@vger.kernel.org # 4.6 Reviewed-by: Saravana Kannan saravanak@google.com Signed-off-by: Johan Hovold johan@kernel.org Signed-off-by: Bartosz Golaszewski bgolaszewski@baylibre.com [ johan: adjust context to 5.11 ] Signed-off-by: Johan Hovold johan@kernel.org --- drivers/gpio/gpiolib.c | 4 ++++ 1 file changed, 4 insertions(+)
diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c index adf55db080d8..0069b115928c 100644 --- a/drivers/gpio/gpiolib.c +++ b/drivers/gpio/gpiolib.c @@ -475,8 +475,12 @@ EXPORT_SYMBOL_GPL(gpiochip_line_is_valid); static void gpiodevice_release(struct device *dev) { struct gpio_device *gdev = dev_get_drvdata(dev); + unsigned long flags;
+ spin_lock_irqsave(&gpio_lock, flags); list_del(&gdev->list); + spin_unlock_irqrestore(&gpio_lock, flags); + ida_free(&gpio_ida, gdev->id); kfree_const(gdev->label); kfree(gdev->descs);