[S390] keyboard: integer underflow bug

The "ct" variable should be an unsigned int.  Both struct kbdiacrs
->kb_cnt and struct kbd_data ->accent_table_size are unsigned ints.

Making it signed causes a problem in KBDIACRUC because the user could
set the signed bit and cause a buffer overflow.

Cc: <stable@kernel.org>
Signed-off-by: Dan Carpenter <error27@gmail.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

diff --git a/drivers/s390/char/keyboard.c b/drivers/s390/char/keyboard.c
index 8cd58e412b5eae2cfe3188a03f616190146f8db0..5ad44daef73bdf5ea54eac6e5885c068042d7dd1 100644 (file)
--- a/drivers/s390/char/keyboard.c
+++ b/drivers/s390/char/keyboard.c
@@ -460,7 +460,8 @@ kbd_ioctl(struct kbd_data *kbd, struct file *file,
          unsigned int cmd, unsigned long arg)
 {
        void __user *argp;
-       int ct, perm;
+       unsigned int ct;
+       int perm;
 
        argp = (void __user *)arg;