[PATCH] gpio: prevent potential speculation leaks in gpio_device_get_desc()
From: Hagar Hemdan
Date: Tue May 14 2024 - 08:27:05 EST
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@xxxxxxxxxx>
---
Only compile tested, no access to HW.
---
drivers/gpio/gpiolib-cdev.c | 10 +++++++---
1 file changed, 7 insertions(+), 3 deletions(-)
diff --git a/drivers/gpio/gpiolib-cdev.c b/drivers/gpio/gpiolib-cdev.c
index 9dad67ea2597..215c03e6808f 100644
--- a/drivers/gpio/gpiolib-cdev.c
+++ b/drivers/gpio/gpiolib-cdev.c
@@ -20,6 +20,7 @@
#include <linux/kfifo.h>
#include <linux/module.h>
#include <linux/mutex.h>
+#include <linux/nospec.h>
#include <linux/overflow.h>
#include <linux/pinctrl/consumer.h>
#include <linux/poll.h>
@@ -2170,7 +2171,8 @@ static int lineevent_create(struct gpio_device *gdev, void __user *ip)
lflags = eventreq.handleflags;
eflags = eventreq.eventflags;
- desc = gpio_device_get_desc(gdev, offset);
+ desc = gpio_device_get_desc(gdev,
+ array_index_nospec(offset, gdev->ngpio));
if (IS_ERR(desc))
return PTR_ERR(desc);
@@ -2477,7 +2479,8 @@ static int lineinfo_get_v1(struct gpio_chardev_data *cdev, void __user *ip,
return -EFAULT;
/* this doubles as a range check on line_offset */
- desc = gpio_device_get_desc(cdev->gdev, lineinfo.line_offset);
+ desc = gpio_device_get_desc(cdev->gdev,
+ array_index_nospec(lineinfo.line_offset, cdev->gdev->ngpio));
if (IS_ERR(desc))
return PTR_ERR(desc);
@@ -2514,7 +2517,8 @@ static int lineinfo_get(struct gpio_chardev_data *cdev, void __user *ip,
if (memchr_inv(lineinfo.padding, 0, sizeof(lineinfo.padding)))
return -EINVAL;
- desc = gpio_device_get_desc(cdev->gdev, lineinfo.offset);
+ desc = gpio_device_get_desc(cdev->gdev,
+ array_index_nospec(lineinfo.offset, cdev->gdev->ngpio));
if (IS_ERR(desc))
return PTR_ERR(desc);
--
2.40.1