From: Kent Gibson <warthog618@gmail.com>
To: Bartosz Golaszewski <brgl@bgdev.pl>
Cc: Linus Walleij <linus.walleij@linaro.org>,
Andy Shevchenko <andriy.shevchenko@linux.intel.com>,
linux-gpio@vger.kernel.org, linux-kernel@vger.kernel.org,
Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
Subject: Re: [PATCH v5 1/2] gpiolib: cdev: fix NULL-pointer dereferences
Date: Thu, 1 Dec 2022 18:57:22 +0800 [thread overview]
Message-ID: <Y4iIkgvnsBMxsE89@sol> (raw)
In-Reply-To: <20221201083335.819190-2-brgl@bgdev.pl>
On Thu, Dec 01, 2022 at 09:33:34AM +0100, Bartosz Golaszewski wrote:
> From: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
>
> There are several places where we can crash the kernel by requesting
> lines, unbinding the GPIO device, then calling any of the system calls
> relevant to the GPIO character device's annonymous file descriptors:
> ioctl(), read(), poll().
>
> While I observed it with the GPIO simulator, it will also happen for any
> of the GPIO devices that can be hot-unplugged - for instance any HID GPIO
> expander (e.g. CP2112).
>
> This affects both v1 and v2 uAPI.
>
> This fixes it partially by checking if gdev->chip is not NULL but it
> doesn't entirely remedy the situation as we still have a race condition
> in which another thread can remove the device after the check.
>
> Fixes: d7c51b47ac11 ("gpio: userspace ABI for reading/writing GPIO lines")
> Fixes: 3c0d9c635ae2 ("gpiolib: cdev: support GPIO_V2_GET_LINE_IOCTL and GPIO_V2_LINE_GET_VALUES_IOCTL")
> Fixes: aad955842d1c ("gpiolib: cdev: support GPIO_V2_GET_LINEINFO_IOCTL and GPIO_V2_GET_LINEINFO_WATCH_IOCTL")
> Fixes: a54756cb24ea ("gpiolib: cdev: support GPIO_V2_LINE_SET_CONFIG_IOCTL")
> Fixes: 7b8e00d98168 ("gpiolib: cdev: support GPIO_V2_LINE_SET_VALUES_IOCTL")
> Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
> Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
As per v4, I'm fine with whole series, so
Reviewed-by: Kent Gibson <warthog618@gmail.com>
Cheers,
Kent.
next prev parent reply other threads:[~2022-12-01 10:57 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-12-01 8:33 [PATCH v5 0/2] gpiolib: don't allow user-space to crash the kernel with hot-unplugs Bartosz Golaszewski
2022-12-01 8:33 ` [PATCH v5 1/2] gpiolib: cdev: fix NULL-pointer dereferences Bartosz Golaszewski
2022-12-01 10:57 ` Kent Gibson [this message]
2022-12-01 12:07 ` Andy Shevchenko
2022-12-01 8:33 ` [PATCH v5 2/2] gpiolib: protect the GPIO device against being dropped while in use by user-space Bartosz Golaszewski
2022-12-01 12:01 ` Andy Shevchenko
2022-12-01 12:12 ` Bartosz Golaszewski
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