[PATCH] ebcdic do_kdsk_ioctl off-by-one

Add a missing return check from strnlen_user and fixes a off-by-one when
terminating the string with zero.

Signed-off-by: Davi Arnaut <davi.arnaut@gmail.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

diff --git a/drivers/s390/char/keyboard.c b/drivers/s390/char/keyboard.c
index 5bda234..a317a12 100644 (file)
--- a/drivers/s390/char/keyboard.c
+++ b/drivers/s390/char/keyboard.c
@@ -440,7 +440,11 @@ do_kdgkb_ioctl(struct kbd_data *kbd, struct kbsentry __user *u_kbs,
                        return -EPERM;
                len = strnlen_user(u_kbs->kb_string,
                                   sizeof(u_kbs->kb_string) - 1);
-               p = kmalloc(len, GFP_KERNEL);
+               if (!len)
+                       return -EFAULT;
+               if (len > sizeof(u_kbs->kb_string) - 1)
+                       return -EINVAL;
+               p = kmalloc(len + 1, GFP_KERNEL);
                if (!p)
                        return -ENOMEM;
                if (copy_from_user(p, u_kbs->kb_string, len)) {