| Message ID | 20240517090904.22812-1-hagarhem@amazon.com |
|---|---|
| State | New |
| Headers | show |
| Series | [v2] gpio: prevent potential speculation leaks in gpio_device_get_desc() | expand |
On Fri, May 17, 2024 at 09:09:04AM +0000, Hagar Hemdan wrote: > Users can call the gpio_ioctl() interface to get information about gpio > chip lines. > Lines on the chip are identified by an offset in the range > of [0,chip.lines). > Offset is copied from user and then used as an array index to get > the gpio descriptor without sanitization. > > This change ensures that the offset is sanitized by > "using array_index_nospec" to mitigate any possibility of speculative > information leaks. > This could better describe the problem. I'm still not 100% sure I understand it, so it would be great if the comment could clarify it, specifically what "speculation leaks" means. And when referencing functions use (), so array_index_nospec(), rather than quotes. > This bug was discovered and resolved using Coverity Static Analysis > Security Testing (SAST) by Synopsys, Inc. > > Fixes: aad955842d1c ("gpiolib: cdev: support GPIO_V2_GET_LINEINFO_IOCTL and GPIO_V2_GET_LINEINFO_WATCH_IOCTL") This is not the correct commit(s) - the bug would've been present in the character device uAPI since it was first added. In fact two out of three places you patched in v1 pre-date this commit. > Signed-off-by: Hagar Hemdan <hagarhem@amazon.com> > --- > v2: call array_index_nospec() after the bounds check. > --- > drivers/gpio/gpiolib.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c > index fa50db0c3605..b58e4fe78cec 100644 > --- a/drivers/gpio/gpiolib.c > +++ b/drivers/gpio/gpiolib.c > @@ -17,6 +17,7 @@ > #include <linux/list.h> > #include <linux/lockdep.h> > #include <linux/module.h> > +#include <linux/nospec.h> > #include <linux/of.h> > #include <linux/pinctrl/consumer.h> > #include <linux/seq_file.h> > @@ -201,7 +202,7 @@ gpio_device_get_desc(struct gpio_device *gdev, unsigned int hwnum) > if (hwnum >= gdev->ngpio) > return ERR_PTR(-EINVAL); > > - return &gdev->descs[hwnum]; > + return &gdev->descs[array_index_nospec(hwnum, gdev->ngpio)]; > } > EXPORT_SYMBOL_GPL(gpio_device_get_desc); > That makes more sense to me, so I no problem with the code change. Cheers, Kent.
diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c index fa50db0c3605..b58e4fe78cec 100644 --- a/drivers/gpio/gpiolib.c +++ b/drivers/gpio/gpiolib.c @@ -17,6 +17,7 @@ #include <linux/list.h> #include <linux/lockdep.h> #include <linux/module.h> +#include <linux/nospec.h> #include <linux/of.h> #include <linux/pinctrl/consumer.h> #include <linux/seq_file.h> @@ -201,7 +202,7 @@ gpio_device_get_desc(struct gpio_device *gdev, unsigned int hwnum) if (hwnum >= gdev->ngpio) return ERR_PTR(-EINVAL); - return &gdev->descs[hwnum]; + return &gdev->descs[array_index_nospec(hwnum, gdev->ngpio)]; } EXPORT_SYMBOL_GPL(gpio_device_get_desc);
Users can call the gpio_ioctl() interface to get information about gpio chip lines. Lines on the chip are identified by an offset in the range of [0,chip.lines). Offset is copied from user and then used as an array index to get the gpio descriptor without sanitization. This change ensures that the offset is sanitized by "using array_index_nospec" to mitigate any possibility of speculative information leaks. This bug was discovered and resolved using Coverity Static Analysis Security Testing (SAST) by Synopsys, Inc. Fixes: aad955842d1c ("gpiolib: cdev: support GPIO_V2_GET_LINEINFO_IOCTL and GPIO_V2_GET_LINEINFO_WATCH_IOCTL") Signed-off-by: Hagar Hemdan <hagarhem@amazon.com> --- v2: call array_index_nospec() after the bounds check. --- drivers/gpio/gpiolib.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)