On Fri, May 17, 2019 at 09:55:02AM +0200, Johan Hovold wrote:
> On Thu, May 16, 2019 at 12:09:31PM +0800, YueHaibing wrote:
> > If ulite_probe is not called or failed to registed
> > uart_register_driver, unload the module will call
> > uart_unregister_driver, which will tigger NULL
> > pointer dereference like this:
> >
> > BUG: KASAN: null-ptr-deref in tty_unregister_driver+0x19/0x100
> > Read of size 4 at addr 0000000000000034 by task syz-executor.0/4246
>
> > This patch fix this by moving uart_unregister_driver
> > to ulite_remove.
> >
> > Reported-by: Hulk Robot <hulkci@xxxxxxxxxx>
> > Fixes: 415b43bdb008 ("tty: serial: uartlite: Move uart register to probe")
> > Signed-off-by: YueHaibing <yuehaibing@xxxxxxxxxx>
> > ---
> > drivers/tty/serial/uartlite.c | 2 +-
> > 1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/drivers/tty/serial/uartlite.c b/drivers/tty/serial/uartlite.c
> > index b8b912b..2e49fb6 100644
> > --- a/drivers/tty/serial/uartlite.c
> > +++ b/drivers/tty/serial/uartlite.c
> > @@ -867,6 +867,7 @@ static int ulite_remove(struct platform_device *pdev)
> > pm_runtime_disable(&pdev->dev);
> > pm_runtime_set_suspended(&pdev->dev);
> > pm_runtime_dont_use_autosuspend(&pdev->dev);
> > + uart_unregister_driver(&ulite_uart_driver);
>
> This broken. Consider what happens if you have tho ports registered and
> you unbind the first.
>
> Someone else sent a fix for this here
>
> https://lkml.kernel.org/r/20190514033219.169947-1-wangkefeng.wang@xxxxxxxxxx
>
> That fix also has some issues, but is still better given the current
> state this driver is in.
I'm not taking any of these patches until people agree on what needs to
be done here :)
Why is this driver so "special" it is having these types of problems?
Why can't it do what all other drivers do in this case?
thanks,
greg k-h
