linux-kernel - [PATCH] gpio: prevent potential speculation leaks in gpio_device_get

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-next>] [day] [month] [year] [list]

Message-ID: <20240514122601.15261-1-hagarhem@amazon.com>
Date: Tue, 14 May 2024 12:26:01 +0000
From: Hagar Hemdan <hagarhem@...zon.com>
To:
CC: Norbert Manthey <nmanthey@...zon.de>, Hagar Hemdan <hagarhem@...zon.com>,
	Bartosz Golaszewski <brgl@...ev.pl>, Kent Gibson <warthog618@...il.com>,
	Linus Walleij <linus.walleij@...aro.org>, <linux-gpio@...r.kernel.org>,
	<linux-kernel@...r.kernel.org>
Subject: [PATCH] gpio: prevent potential speculation leaks in 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@...zon.com>
---
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