On 30.05.22 09:08, Muchun Song wrote:
> 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.
>
I'm curious how both of you found that issue? Just by staring at that
code? :)
--
Thanks,
David / dhildenb
