Re: [PATCH v2] acpi: Fix use-after-free in acpi_ipmi.c

[Youling Tang]

Hi,

On 11/26/2020 10:22 PM, Rafael J. Wysocki wrote:
> On Thu, Nov 26, 2020 at 2:26 AM Youling Tang <tangyouling@xxxxxxxxxxx> wrote:
> > kfree() has been called inside put_device so anther kfree would cause a
> > use-after-free bug.
> >
> > Signed-off-by: Youling Tang <tangyouling@xxxxxxxxxxx>
> > ---
> >   drivers/acpi/acpi_ipmi.c | 1 -
> >   1 file changed, 1 deletion(-)
> >
> > diff --git a/drivers/acpi/acpi_ipmi.c b/drivers/acpi/acpi_ipmi.c
> > index 9d6c0fc..18edf8b 100644
> > --- a/drivers/acpi/acpi_ipmi.c
> > +++ b/drivers/acpi/acpi_ipmi.c
> > @@ -142,7 +142,6 @@ static void ipmi_dev_release(struct acpi_ipmi_device *ipmi_device)
> >   {
> >          ipmi_destroy_user(ipmi_device->user_interface);
> >          put_device(ipmi_device->dev);
> Does putting ipmi_device->dev (which is a different object than
> ipmi_device itself) really cause ipmi_device to be freed
> automatically?  If not, the change below will introduce a memory leak.
ipmi_device will be free so that there is no memory leak.
Similar to the following:
https://lore.kernel.org/patchwork/patch/1342136/

Thanks,
Youling.
> > -       kfree(ipmi_device);
> >   }
> >
> >   static void ipmi_dev_release_kref(struct kref *kref)
> > --