Re: [Openipmi-developer] [PATCH v2] ipmi_si: fix use-after-free of resource->name

[Yang Yingliang]

On 2019/1/26 23:08, Corey Minyard wrote:
> On Sat, Jan 26, 2019 at 05:14:54PM +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 io_cleanup() while try_smi_init() goes to out_err
> > 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>
> > Suggested-by: Corey Minyard <cminyard@xxxxxxxxxx>
> > Signed-off-by: Yang Yingliang <yangyingliang@xxxxxxxxxx>
> > ---
> >   drivers/char/ipmi/ipmi_si_intf.c    | 5 +++++
> >   drivers/char/ipmi/ipmi_si_port_io.c | 3 +++
> >   2 files changed, 8 insertions(+)
> >
> > diff --git a/drivers/char/ipmi/ipmi_si_intf.c b/drivers/char/ipmi/ipmi_si_intf.c
> > index dc8603d..f1b9fda 100644
> > --- a/drivers/char/ipmi/ipmi_si_intf.c
> > +++ b/drivers/char/ipmi/ipmi_si_intf.c
> > @@ -2085,6 +2085,11 @@ static int try_smi_init(struct smi_info *new_smi)
> >   	WARN_ON(new_smi->io.dev->init_name != NULL);
> >   
> >    out_err:
> > +	if (rv && new_smi->io.io_cleanup) {
> > +		new_smi->io.io_cleanup(&new_smi->io);
> > +		new_smi->io.io_cleanup = NULL;
> > +	}
> > +
> >   	kfree(init_name);
> >   	return rv;
> >   }
> > 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;
> > +
> Why do you need this part?  I can't see the reason for it.  The addr
> part below should handle that, especially with the above change.
>
> -corey
If ipmi_si_port_setup() returns in default case, request_region() won't 
be called,
so we don't need to call release_region() or it will prints some warning 
messages like
this "Trying to free nonexistent resource...".

We don't need call io_cleanup() until the io_setup() returns successful.
How about change this part like this:

diff --git a/drivers/char/ipmi/ipmi_si_port_io.c 
b/drivers/char/ipmi/ipmi_si_port_io.c
index ef6dffc..03924c3 100644
--- a/drivers/char/ipmi/ipmi_si_port_io.c
+++ b/drivers/char/ipmi/ipmi_si_port_io.c
@@ -68,8 +68,6 @@ int ipmi_si_port_setup(struct si_sm_io *io)
        if (!addr)
                return -ENODEV;

-       io->io_cleanup = port_cleanup;
-
        /*
         * Figure out the actual inb/inw/inl/etc routine to use based
         * upon the register size.
@@ -109,5 +107,8 @@ int ipmi_si_port_setup(struct si_sm_io *io)
                        return -EIO;
                }
        }
+
+       io->io_cleanup = port_cleanup;
+
        return 0;
 }

Thanks,
Yang
> >   	if (addr) {
> >   		for (idx = 0; idx < io->io_size; idx++)
> >   			release_region(addr + idx * io->regspacing,
> > --
> > 1.8.3
> >
> >
> >
> >
> > _______________________________________________
> > Openipmi-developer mailing list
> > Openipmi-developer@xxxxxxxxxxxxxxxxxxxxx
> > https://lists.sourceforge.net/lists/listinfo/openipmi-developer
> .