[PATCH] misc: xilinx-sdfec: remove check for ioctl cmd and argument.

[PATCH] misc: xilinx-sdfec: remove check for ioctl cmd and argument.

[Harshal Chaudhari]

if (_IOC_TYPE(cmd) != PP_IOCTL)
        return -ENOTTY;

Invalid ioctl command check normally performs by “default” case.

if (_IOC_DIR(cmd) != _IOC_NONE) {
       argp = (void __user *)arg;
       if (!argp)
             return -EINVAL; }

And for checking ioctl arguments, copy_from_user()/copy_to_user()
checks are enough.

Signed-off-by: Harshal Chaudhari <harshalchau04@gmail.com>
---
 drivers/misc/xilinx_sdfec.c | 16 +++-------------
 1 file changed, 3 insertions(+), 13 deletions(-)

diff --git a/drivers/misc/xilinx_sdfec.c b/drivers/misc/xilinx_sdfec.c
index 92291292756a..ff104c894b3b 100644
--- a/drivers/misc/xilinx_sdfec.c
+++ b/drivers/misc/xilinx_sdfec.c
@@ -944,8 +944,8 @@ static long xsdfec_dev_ioctl(struct file *fptr, unsigned int cmd,
 			     unsigned long data)
 {
 	struct xsdfec_dev *xsdfec;
-	void __user *arg = NULL;
-	int rval = -EINVAL;
+	void __user *arg = (void __user *)data;
+	int rval;
 
 	xsdfec = container_of(fptr->private_data, struct xsdfec_dev, miscdev);
 
@@ -956,16 +956,6 @@ static long xsdfec_dev_ioctl(struct file *fptr, unsigned int cmd,
 		return -EPERM;
 	}
 
-	if (_IOC_TYPE(cmd) != XSDFEC_MAGIC)
-		return -ENOTTY;
-
-	/* check if ioctl argument is present and valid */
-	if (_IOC_DIR(cmd) != _IOC_NONE) {
-		arg = (void __user *)data;
-		if (!arg)
-			return rval;
-	}
-
 	switch (cmd) {
 	case XSDFEC_START_DEV:
 		rval = xsdfec_start(xsdfec);
@@ -1010,7 +1000,7 @@ static long xsdfec_dev_ioctl(struct file *fptr, unsigned int cmd,
 		rval = xsdfec_is_active(xsdfec, (bool __user *)arg);
 		break;
 	default:
-		/* Should not get here */
+		rval = -ENOTTY;
 		break;
 	}
 	return rval;
-- 
2.17.1

Re: [PATCH] misc: xilinx-sdfec: remove check for ioctl cmd and argument.

[Arnd Bergmann]

On Sun, Nov 1, 2020 at 6:09 PM Harshal Chaudhari
<harshalchau04@gmail.com> wrote:
>
> if (_IOC_TYPE(cmd) != PP_IOCTL)
>         return -ENOTTY;
>
> Invalid ioctl command check normally performs by “default” case.
>
> if (_IOC_DIR(cmd) != _IOC_NONE) {
>        argp = (void __user *)arg;
>        if (!argp)
>              return -EINVAL; }
>
> And for checking ioctl arguments, copy_from_user()/copy_to_user()
> checks are enough.
>
> Signed-off-by: Harshal Chaudhari <harshalchau04@gmail.com>

Thanks for following up on this,

Reviewed-by: Arnd Bergmann <arnd@arndb.de>

RE: [PATCH] misc: xilinx-sdfec: remove check for ioctl cmd and argument.

[Dragan Cvetic]

> -----Original Message-----
> From: Harshal Chaudhari <harshalchau04@gmail.com>
> Sent: Sunday 1 November 2020 17:10
> To: gregkh@linuxfoundation.org; Dragan Cvetic <draganc@xilinx.com>
> Cc: Derek Kiernan <dkiernan@xilinx.com>; arnd@arndb.de; Michal Simek <michals@xilinx.com>; linux-arm-
> kernel@lists.infradead.org; linux-kernel@vger.kernel.org
> Subject: [PATCH] misc: xilinx-sdfec: remove check for ioctl cmd and argument.
> 
> if (_IOC_TYPE(cmd) != PP_IOCTL)
>         return -ENOTTY;
> 
> Invalid ioctl command check normally performs by “default” case.
> 
> if (_IOC_DIR(cmd) != _IOC_NONE) {
>        argp = (void __user *)arg;
>        if (!argp)
>              return -EINVAL; }
> 
> And for checking ioctl arguments, copy_from_user()/copy_to_user()
> checks are enough.
> 
> Signed-off-by: Harshal Chaudhari <harshalchau04@gmail.com>
> ---
>  drivers/misc/xilinx_sdfec.c | 16 +++-------------
>  1 file changed, 3 insertions(+), 13 deletions(-)
> 
> diff --git a/drivers/misc/xilinx_sdfec.c b/drivers/misc/xilinx_sdfec.c
> index 92291292756a..ff104c894b3b 100644
> --- a/drivers/misc/xilinx_sdfec.c
> +++ b/drivers/misc/xilinx_sdfec.c
> @@ -944,8 +944,8 @@ static long xsdfec_dev_ioctl(struct file *fptr, unsigned int cmd,
>  			     unsigned long data)
>  {
>  	struct xsdfec_dev *xsdfec;
> -	void __user *arg = NULL;
> -	int rval = -EINVAL;
> +	void __user *arg = (void __user *)data;
> +	int rval;
> 
>  	xsdfec = container_of(fptr->private_data, struct xsdfec_dev, miscdev);
> 
> @@ -956,16 +956,6 @@ static long xsdfec_dev_ioctl(struct file *fptr, unsigned int cmd,
>  		return -EPERM;
>  	}
> 
> -	if (_IOC_TYPE(cmd) != XSDFEC_MAGIC)
> -		return -ENOTTY;
> -
> -	/* check if ioctl argument is present and valid */
> -	if (_IOC_DIR(cmd) != _IOC_NONE) {
> -		arg = (void __user *)data;
> -		if (!arg)
> -			return rval;
> -	}
> -
>  	switch (cmd) {
>  	case XSDFEC_START_DEV:
>  		rval = xsdfec_start(xsdfec);
> @@ -1010,7 +1000,7 @@ static long xsdfec_dev_ioctl(struct file *fptr, unsigned int cmd,
>  		rval = xsdfec_is_active(xsdfec, (bool __user *)arg);
>  		break;
>  	default:
> -		/* Should not get here */
> +		rval = -ENOTTY;
>  		break;
>  	}
>  	return rval;
> --
> 2.17.1

Acked-by: Dragan Cvetic <dragan.cvetic@xilinx.com>