Hello Christoph Hellwig,

The patch a7b75c5a8c41: "net: pass a sockptr_t into ->setsockopt"
from Jul 23, 2020, leads to the following Smatch static checker
warnings:

net/netrom/af_netrom.c:309 nr_setsockopt() warn: not copying enough bytes for '&opt' (8 vs 4 bytes)
net/bluetooth/hci_sock.c:1940 hci_sock_setsockopt() warn: not copying enough bytes for '&opt' (4 vs 2 bytes)
net/bluetooth/l2cap_sock.c:1088 l2cap_sock_setsockopt() warn: not copying enough bytes for '&opt' (4 vs 2 bytes)
net/bluetooth/l2cap_sock.c:1119 l2cap_sock_setsockopt() warn: not copying enough bytes for '&opt' (4 vs 1 bytes)
net/ax25/af_ax25.c:546 ax25_setsockopt() warn: not copying enough bytes for '&opt' (8 vs 4 bytes)

net/netrom/af_netrom.c
    296 static int nr_setsockopt(struct socket *sock, int level, int optname,
    297                 sockptr_t optval, unsigned int optlen)
    298 {
    299         struct sock *sk = sock->sk;
    300         struct nr_sock *nr = nr_sk(sk);
    301         unsigned long opt;
                ^^^^^^^^^^^^^^^^^^

    302 
    303         if (level != SOL_NETROM)
    304                 return -ENOPROTOOPT;
    305 
    306         if (optlen < sizeof(unsigned int))
    307                 return -EINVAL;
    308 
--> 309         if (copy_from_sockptr(&opt, optval, sizeof(unsigned int)))

Originally this was if (get_user(opt, (unsigned int __user *)optval))
which is weird but actually works.  Now the last two bytes are
uninitialized.

    310                 return -EFAULT;
    311 
    312         switch (optname) {
    313         case NETROM_T1:
    314                 if (opt < 1 || opt > ULONG_MAX / HZ)
    315                         return -EINVAL;
    316                 nr->t1 = opt * HZ;
    317                 return 0;

regards,
dan carpenter