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: sta...@vger.kernel.org
Reported-by: NuoHan Qiao <qiaonuo...@huawei.com>
Signed-off-by: Yang Yingliang <yangyingli...@huawei.com>
---
  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

.