Hi Yingliang, On 2020/7/21 22:38, Yang Yingliang wrote: (SNIP) > > SERIAL_PORT_DFNS is not defined on each arch, if it's not defined, > serial8250_set_defaults() won't be called in serial8250_isa_init_ports(), > so the p->serial_in pointer won't be initialized, and it leads a > null-ptr-deref. > Fix this problem by calling serial8250_set_defaults() after init uart port. > > Signed-off-by: Yang Yingliang <yangyingli...@huawei.com> > --- > drivers/tty/serial/8250/8250_core.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/drivers/tty/serial/8250/8250_core.c > b/drivers/tty/serial/8250/8250_core.c > index fc118f649887..cae61d1ebec5 100644 > --- a/drivers/tty/serial/8250/8250_core.c > +++ b/drivers/tty/serial/8250/8250_core.c > @@ -524,6 +524,7 @@ static void __init serial8250_isa_init_ports(void) > */ > up->mcr_mask = ~ALPHA_KLUDGE_MCR; > up->mcr_force = ALPHA_KLUDGE_MCR; > + serial8250_set_defaults(up);
That is really a good catch, but this modification looks not good to me. First, serial8250_set_defaults()'s parameter 'up' updated in the loop below is used to lead to different branch in this function. So that the logic is broken. Second, up->port.iobase and up->port.iotype are both initialized to 0, so the 'serial_in' and 'serial_out' will be assigned to the ops for IO space with port 0 here, i don't think that is correct. > } > > /* chain base port ops to support Remote Supervisor Adapter */ > @@ -547,7 +548,6 @@ static void __init serial8250_isa_init_ports(void) > port->membase = old_serial_port[i].iomem_base; > port->iotype = old_serial_port[i].io_type; > port->regshift = old_serial_port[i].iomem_reg_shift; > - serial8250_set_defaults(up); > > port->irqflags |= irqflag; > if (serial8250_isa_config != NULL) > Thanks, Wei
