On Mon, May 30, 2022 at 2:56 PM David Hildenbrand <david@xxxxxxxxxx> wrote:
>
> On 30.05.22 07:33, Muchun Song wrote:
> > The device_unregister() is supposed to be used to unregister devices if
> > device_register() has succeed. And device_unregister() will put device.
> > The caller should not do it again, otherwise, the first call of
> > put_device() will drop the last reference count, then the next call
> > of device_unregister() will UAF on device.
> >
> > Fixes: 4fb6eabf1037 ("drivers/base/memory.c: cache memory blocks in xarray to accelerate lookup")
> > Signed-off-by: Muchun Song <songmuchun@xxxxxxxxxxxxx>
> > Cc: <stable@xxxxxxxxxxxxxxx>
> > ---
> > drivers/base/memory.c | 5 ++---
> > 1 file changed, 2 insertions(+), 3 deletions(-)
> >
> > diff --git a/drivers/base/memory.c b/drivers/base/memory.c
> > index 7222ff9b5e05..084d67fd55cc 100644
> > --- a/drivers/base/memory.c
> > +++ b/drivers/base/memory.c
> > @@ -636,10 +636,9 @@ static int __add_memory_block(struct memory_block *memory)
> > }
> > ret = xa_err(xa_store(&memory_blocks, memory->dev.id, memory,
> > GFP_KERNEL));
> > - if (ret) {
> > - put_device(&memory->dev);
> > + if (ret)
> > device_unregister(&memory->dev);
> > - }
> > +
> > return ret;
> > }
> >
>
> See
>
> https://lkml.kernel.org/r/d44c63d78affe844f020dc02ad6af29abc448fc4.1650611702.git.christophe.jaillet@xxxxxxxxxx
>
I see. Good job by Christophe. Thanks David.
