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Subject[PATCH v2] gpio: prevent potential speculation leaks in gpio_device_get_desc()
Date
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(-)

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);

--
2.40.1

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