Re: [PATCH] ipmi_si: fix use-after-free of resource->name

[Yang Yingliang]

On 2019/1/26 4:35, Corey Minyard wrote:
> On Fri, Jan 25, 2019 at 10:30:59AM +0800, Yang Yingliang wrote:
> > When we excute the following commands, we got oops
> > rmmod ipmi_si
> > cat /proc/ioports
> snip...
>
> > If io_setup is called successful in try_smi_init() but try_smi_init()
> > goes out_err before calling ipmi_register_smi(), so ipmi_unregister_smi()
> > will not be called while removing module. It leads to the resource that
> > allocated in io_setup() can not be freed, but the name(DEVICE_NAME) of
> > resource is freed while removing the module. It causes use-after-free
> > when cat /proc/ioports.
> >
> > Fix this by calling shutdown_smi() while removing the module and don't
> > call release_region() if request_region() is not called to avoid error
> > prints.
> >
> > Fixes: 93c303d2045b ("ipmi_si: Clean up shutdown a bit")
> > Cc: stable@xxxxxxxxxxxxxxx
> > Reported-by: NuoHan Qiao <qiaonuohan@xxxxxxxxxx>
> > Signed-off-by: Yang Yingliang <yangyingliang@xxxxxxxxxx>
> > ---
> >   drivers/char/ipmi/ipmi_si_intf.c    | 2 ++
> >   drivers/char/ipmi/ipmi_si_port_io.c | 3 +++
> >   2 files changed, 5 insertions(+)
> >
> > diff --git a/drivers/char/ipmi/ipmi_si_intf.c b/drivers/char/ipmi/ipmi_si_intf.c
> > index dc8603d..635e98a 100644
> > --- a/drivers/char/ipmi/ipmi_si_intf.c
> > +++ b/drivers/char/ipmi/ipmi_si_intf.c
> > @@ -2235,6 +2235,8 @@ static void cleanup_one_si(struct smi_info *smi_info)
> >   
> >   	if (smi_info->intf)
> >   		ipmi_unregister_smi(smi_info->intf);
> > +	else
> > +		shutdown_smi(smi_info);
> This is completely the wrong way to fix this.  The general principle is
> that a function cleans up for itself if it returns an error.  If you
> add hacks other places for a function failing you end up with a mess.
>
> I think the right way to fix this is to add something like:
>
> 	if (rv && new_smi->io.io_size && smi_info->io.io_cleanup) {
> 		smi_info->io.io_cleanup(&smi_info->io);
> 		smi_info->io.io_cleanup = NULL;
> 	}
>
> at the end of try_smi_init().
>
> -corey
OK, I will do some test, and send v2 later.

Thanks,
Yang
> >   
> >   	if (smi_info->pdev) {
> >   		if (smi_info->pdev_registered)
> > diff --git a/drivers/char/ipmi/ipmi_si_port_io.c b/drivers/char/ipmi/ipmi_si_port_io.c
> > index ef6dffc..0c46a3f 100644
> > --- a/drivers/char/ipmi/ipmi_si_port_io.c
> > +++ b/drivers/char/ipmi/ipmi_si_port_io.c
> > @@ -53,6 +53,9 @@ static void port_cleanup(struct si_sm_io *io)
> >   	unsigned int addr = io->addr_data;
> >   	int          idx;
> >   
> > +	if (io->regsize != 1 && io->regsize != 2 && io->regsize != 4)
> > +		return;
> > +
> >   	if (addr) {
> >   		for (idx = 0; idx < io->io_size; idx++)
> >   			release_region(addr + idx * io->regspacing,
> > --
> > 1.8.3
> .