1 files changed, 1 insertions, 1 deletions

diff --git a/drivers/s390/char/sclp_async.c b/drivers/s390/char/sclp_async.c
index 2aecf7f21361..7ad30e72f868 100644
--- a/drivers/s390/char/sclp_async.c
+++ b/drivers/s390/char/sclp_async.c
@@ -85,7 +85,7 @@ static int proc_handler_callhome(struct ctl_table *ctl, int write,
                 rc = copy_from_user(buf, buffer, sizeof(buf));
                 if (rc != 0)
                         return -EFAULT;
-                buf[len - 1] = '\0';
+                buf[sizeof(buf) - 1] = '\0';
                 if (strict_strtoul(buf, 0, &val) != 0)
                         return -EINVAL;
                 if (val != 0 && val != 1)