keyboard: integer underflow bug

commit b652277b09d3d030cb074cc6a98ba80b34244c03 upstream.

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.

Signed-off-by: Dan Carpenter <error27@gmail.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

diff --git a/drivers/s390/char/keyboard.c b/drivers/s390/char/keyboard.c
index cee4d4e4242907bb7a917070b0e3ac7b706cb794..1160fca436632f1b07b7978cfa96f11486ee9f6a 100644 (file)
--- a/drivers/s390/char/keyboard.c
+++ b/drivers/s390/char/keyboard.c
@@ -462,7 +462,8 @@ 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;