From mboxrd@z Thu Jan 1 00:00:00 1970 From: Greg KH Subject: Re: [PATCH] serial-uartlite: Fix null-ptr-deref in ulite_exit Date: Tue, 21 May 2019 12:10:59 +0200 Message-ID: <20190521101059.GB13612@kroah.com> References: <20190516040931.16276-1-yuehaibing@huawei.com> <20190517075502.GE28564@localhost> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <20190517075502.GE28564@localhost> Sender: linux-kernel-owner@vger.kernel.org To: Johan Hovold Cc: YueHaibing , jacmet@sunsite.dk, jslaby@suse.com, shubhrajyoti.datta@xilinx.com, linux-kernel@vger.kernel.org, linux-serial@vger.kernel.org List-Id: linux-serial@vger.kernel.org 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 > > Fixes: 415b43bdb008 ("tty: serial: uartlite: Move uart register to probe") > > Signed-off-by: YueHaibing > > --- > > 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@huawei.com > > 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