[PATCH] char: ppdev: check if ioctl argument is present and valid

[Harshal Chaudhari]

Checking the argument passed to the ioctl is valid
or not. if not then return -EINVAL.

Signed-off-by: Harshal Chaudhari <harshalcha...@gmail.com>
---
 drivers/char/ppdev.c | 12 +++++++++++-
 1 file changed, 11 insertions(+), 1 deletion(-)

diff --git a/drivers/char/ppdev.c b/drivers/char/ppdev.c
index 38b46c7d1737..001392980202 100644
--- a/drivers/char/ppdev.c
+++ b/drivers/char/ppdev.c
@@ -354,7 +354,7 @@ static int pp_do_ioctl(struct file *file, unsigned int cmd, 
unsigned long arg)
        unsigned int minor = iminor(file_inode(file));
        struct pp_struct *pp = file->private_data;
        struct parport *port;
-       void __user *argp = (void __user *)arg;
+       void __user *argp = NULL;
        struct ieee1284_info *info;
        unsigned char reg;
        unsigned char mask;
@@ -364,6 +364,16 @@ static int pp_do_ioctl(struct file *file, unsigned int 
cmd, unsigned long arg)
        struct timespec64 ts;
        int ret;
 
+       if (_IOC_TYPE(cmd) != PP_IOCTL)
+               return -ENOTTY;
+
+       /* check if ioctl argument is present and valid */
+       if (_IOC_DIR(cmd) != _IOC_NONE) {
+               argp = (void __user *)arg;
+               if (!argp)
+                       return -EINVAL;
+       }
+
        /* First handle the cases that don't take arguments. */
        switch (cmd) {
        case PPCLAIM:
-- 
2.17.1