Created attachment 204976 [details]
Proposed patch

There is a possible buffer overflow bug in sc_allocate_keyboard() of sys/dev/syscons/syscons.c.

                k0 = kbd_get_keyboard(idx0);

                for (idx = kbd_find_keyboard2("*", -1, 0);
                     idx != -1;
                     idx = kbd_find_keyboard2("*", -1, idx + 1)) {
                        k = kbd_get_keyboard(idx);

                        if (idx == idx0 || KBD_IS_BUSY(k))
                                continue;

                        bzero(&ki, sizeof(ki));
                        strcpy(ki.kb_name, k->kb_name);
                        ki.kb_unit = k->kb_unit;

                        (void)kbdd_ioctl(k0, KBADDKBD, (caddr_t) &ki);
                }

We should use strncpy to copy into a fixed-size buffer instead of strcpy().

The attachment is the proposed patch.