Prevent crash when socket lock not initialized

[nebkat]

Crash occurs when running any socket related command (e.g. getsockopt) before a socket has been initialized for the first time.

[freakyxue]

hi @nebkat
I don't think it is necessary to judge the value.
because when allocate socket,this value has been judged.
such as:
In alloc_socket() function

#if ESP_LWIP_LOCK
if (!sockets[i].lock) {
/* one time init and never free */
if (sys_mutex_new(&sockets[i].lock) != ERR_OK) {
return -1;
}
}
#endif

[nebkat]

Hi @freakyxue,

The problem is that alloc_socket() only occurs once lwip_socket() has been called for the given socket[i].

In my code I am doing this (to find out about the currently open sockets in the system):

    for (int s = LWIP_SOCKET_OFFSET; s < LWIP_SOCKET_OFFSET + CONFIG_LWIP_MAX_SOCKETS; s++) {
        int err;

        int socktype;
        socklen_t socktype_len = sizeof(socktype);
        err = getsockopt(s, SOL_SOCKET, SO_TYPE, &socktype, &socktype_len);
        if (err < 0) continue;

        ... print info about socket ...
    }

If lwip_socket() hasn't been previously called for a given FD, the lock will not be initialized, and the program crashes on SYS_ARCH_PROTECT_SOCK(sock);, when it should simply return EBADF to getsockopt().

Perhaps more accurately it would be if (!sock->conn), let me know if you want me to update this.

[freakyxue]

hi @nebkat

from this point，it is really a bug.
In tryget_socket_unconn function we can add the judgement:

tryget_socket_unconn(int fd)
{
struct lwip_sock *ret = tryget_socket_unconn_nouse(fd);
if (ret != NULL && ret->conn != NULL) {
if (!sock_inc_used(ret)) {
return NULL;
}
}
return ret;
}