1 files changed, 3 insertions, 0 deletions

diff --git a/drivers/isdn/mISDN/socket.c b/drivers/isdn/mISDN/socket.c
index 7446d8b4282d..8e325227b4c0 100644
--- a/drivers/isdn/mISDN/socket.c
+++ b/drivers/isdn/mISDN/socket.c
@@ -457,6 +457,9 @@ static int data_sock_getsockopt(struct socket *sock, int level, int optname,
         if (get_user(len, optlen))
                 return -EFAULT;
 
+        if (len != sizeof(char))
+                return -EINVAL;
+
         switch (optname) {
         case MISDN_TIME_STAMP:
                 if (_pms(sk)->cmask & MISDN_TIME_STAMP)