diff --git a/net/bluetooth/rfcomm/sock.c b/net/bluetooth/rfcomm/sock.c
index b54e8a530f55..42c55c756b51 100644
--- a/net/bluetooth/rfcomm/sock.c
+++ b/net/bluetooth/rfcomm/sock.c
@@ -629,7 +629,7 @@ static int rfcomm_sock_setsockopt_old(struct socket *sock, int optname,
 
 	switch (optname) {
 	case RFCOMM_LM:
-		if (copy_from_sockptr(&opt, optval, sizeof(u32))) {
+		if (copy_from_sockptr(&opt, optval, min_t(int, sizeof(u32), optlen))) {
 			err = -EFAULT;
 			break;
 		}