Input: uinput - fix undefined behavior in uinput_validate_absinfo()
diff mbox series

Message ID 20190114220448.GA241112@dtor-ws
State Accepted
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Series
  • Input: uinput - fix undefined behavior in uinput_validate_absinfo()
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Commit Message

Dmitry Torokhov Jan. 14, 2019, 10:04 p.m. UTC
An integer overflow may arise in uinput_validate_absinfo() if "max - min"
can't be represented by an "int". We should check for overflow before
trying to use the result.

Reported-by: Kyungtae Kim <kt0755@gmail.com>
Cc: stable@vger.kernel.org
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
---
 drivers/input/misc/uinput.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

Comments

Dmitry Torokhov Jan. 14, 2019, 10:07 p.m. UTC | #1
On Mon, Jan 14, 2019 at 02:04:48PM -0800, Dmitry Torokhov wrote:
> An integer overflow may arise in uinput_validate_absinfo() if "max - min"
> can't be represented by an "int". We should check for overflow before
> trying to use the result.
> 
> Reported-by: Kyungtae Kim <kt0755@gmail.com>
> Cc: stable@vger.kernel.org
> Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
> ---
>  drivers/input/misc/uinput.c | 5 +++--
>  1 file changed, 3 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/input/misc/uinput.c b/drivers/input/misc/uinput.c
> index 8ec483e8688b..26ec603fe220 100644
> --- a/drivers/input/misc/uinput.c
> +++ b/drivers/input/misc/uinput.c
> @@ -39,6 +39,7 @@
>  #include <linux/init.h>
>  #include <linux/fs.h>
>  #include <linux/miscdevice.h>
> +#include <linux/overflow.h>
>  #include <linux/input/mt.h>
>  #include "../input-compat.h"
>  
> @@ -405,7 +406,7 @@ static int uinput_open(struct inode *inode, struct file *file)
>  static int uinput_validate_absinfo(struct input_dev *dev, unsigned int code,
>  				   const struct input_absinfo *abs)
>  {
> -	int min, max;
> +	int min, max, range;
>  
>  	min = abs->minimum;
>  	max = abs->maximum;
> @@ -417,7 +418,7 @@ static int uinput_validate_absinfo(struct input_dev *dev, unsigned int code,
>  		return -EINVAL;
>  	}
>  
> -	if (abs->flat > max - min) {
> +	if (check_sub_overflow(max, min, &range) && abs->flat > range) {

This should be !check_sub_overflow(...) of course.

>  		printk(KERN_DEBUG
>  		       "%s: abs_flat #%02x out of range: %d (min:%d/max:%d)\n",
>  		       UINPUT_NAME, code, abs->flat, min, max);
> -- 
> 2.20.1.97.g81188d93c3-goog
> 
> 
> -- 
> Dmitry
Peter Hutterer Jan. 14, 2019, 10:41 p.m. UTC | #2
On Mon, Jan 14, 2019 at 02:07:56PM -0800, Dmitry Torokhov wrote:
> On Mon, Jan 14, 2019 at 02:04:48PM -0800, Dmitry Torokhov wrote:
> > An integer overflow may arise in uinput_validate_absinfo() if "max - min"
> > can't be represented by an "int". We should check for overflow before
> > trying to use the result.
> > 
> > Reported-by: Kyungtae Kim <kt0755@gmail.com>
> > Cc: stable@vger.kernel.org
> > Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
> > ---
> >  drivers/input/misc/uinput.c | 5 +++--
> >  1 file changed, 3 insertions(+), 2 deletions(-)
> > 
> > diff --git a/drivers/input/misc/uinput.c b/drivers/input/misc/uinput.c
> > index 8ec483e8688b..26ec603fe220 100644
> > --- a/drivers/input/misc/uinput.c
> > +++ b/drivers/input/misc/uinput.c
> > @@ -39,6 +39,7 @@
> >  #include <linux/init.h>
> >  #include <linux/fs.h>
> >  #include <linux/miscdevice.h>
> > +#include <linux/overflow.h>
> >  #include <linux/input/mt.h>
> >  #include "../input-compat.h"
> >  
> > @@ -405,7 +406,7 @@ static int uinput_open(struct inode *inode, struct file *file)
> >  static int uinput_validate_absinfo(struct input_dev *dev, unsigned int code,
> >  				   const struct input_absinfo *abs)
> >  {
> > -	int min, max;
> > +	int min, max, range;
> >  
> >  	min = abs->minimum;
> >  	max = abs->maximum;
> > @@ -417,7 +418,7 @@ static int uinput_validate_absinfo(struct input_dev *dev, unsigned int code,
> >  		return -EINVAL;
> >  	}
> >  
> > -	if (abs->flat > max - min) {
> > +	if (check_sub_overflow(max, min, &range) && abs->flat > range) {
> 
> This should be !check_sub_overflow(...) of course.

Reviewed-by: Peter Hutterer <peter.hutterer@who-t.net> with that in place,
thanks.

Cheers,
   Peter
 

> >  		printk(KERN_DEBUG
> >  		       "%s: abs_flat #%02x out of range: %d (min:%d/max:%d)\n",
> >  		       UINPUT_NAME, code, abs->flat, min, max);
> > -- 
> > 2.20.1.97.g81188d93c3-goog
> > 
> > 
> > -- 
> > Dmitry
> 
> -- 
> Dmitry

Patch
diff mbox series

diff --git a/drivers/input/misc/uinput.c b/drivers/input/misc/uinput.c
index 8ec483e8688b..26ec603fe220 100644
--- a/drivers/input/misc/uinput.c
+++ b/drivers/input/misc/uinput.c
@@ -39,6 +39,7 @@ 
 #include <linux/init.h>
 #include <linux/fs.h>
 #include <linux/miscdevice.h>
+#include <linux/overflow.h>
 #include <linux/input/mt.h>
 #include "../input-compat.h"
 
@@ -405,7 +406,7 @@  static int uinput_open(struct inode *inode, struct file *file)
 static int uinput_validate_absinfo(struct input_dev *dev, unsigned int code,
 				   const struct input_absinfo *abs)
 {
-	int min, max;
+	int min, max, range;
 
 	min = abs->minimum;
 	max = abs->maximum;
@@ -417,7 +418,7 @@  static int uinput_validate_absinfo(struct input_dev *dev, unsigned int code,
 		return -EINVAL;
 	}
 
-	if (abs->flat > max - min) {
+	if (check_sub_overflow(max, min, &range) && abs->flat > range) {
 		printk(KERN_DEBUG
 		       "%s: abs_flat #%02x out of range: %d (min:%d/max:%d)\n",
 		       UINPUT_NAME, code, abs->flat, min, max);