[PATCH] media: hantro: fix use after free bug in hantro_release due to race condition
hverkuil at xs4all.nl
Mon Mar 13 06:47:01 PDT 2023
On 13/03/2023 14:45, Zheng Hacker wrote:
> Hans Verkuil <hverkuil at xs4all.nl> 于2023年3月13日周一 21:17写道：
>> On 07/03/2023 16:35, Zheng Wang wrote:
>>> In hantro_probe, vpu->watchdog_work is bound with
>>> hantro_watchdog. Then hantro_end_prepare_run may
>>> be called to start the work.
>>> If we close the file or remove the module which will
>>> call hantro_release and hantro_remove to make cleanup,
>>> there may be a unfinished work. The possible sequence
>>> is as follows, which will cause a typical UAF bug.
>>> The same thing will happen in hantro_release, and use
>>> ctx after freeing it.
>>> Fix it by canceling the work before cleanup in hantro_release.
>>> CPU0 CPU1
>>> hantro_remove |
>>> v4l2_m2m_release |
>>> kfree(m2m_dev); |
>>> | v4l2_m2m_get_curr_priv
>>> | m2m_dev->curr_ctx //use
>>> Signed-off-by: Zheng Wang <zyytlz.wz at 163.com>
>>> drivers/media/platform/verisilicon/hantro_drv.c | 1 +
>>> 1 file changed, 1 insertion(+)
>>> diff --git a/drivers/media/platform/verisilicon/hantro_drv.c b/drivers/media/platform/verisilicon/hantro_drv.c
>>> index b0aeedae7b65..cf00ccaa7829 100644
>>> --- a/drivers/media/platform/verisilicon/hantro_drv.c
>>> +++ b/drivers/media/platform/verisilicon/hantro_drv.c
>>> @@ -601,6 +601,7 @@ static int hantro_release(struct file *filp)
>>> * No need for extra locking because this was the last reference
>>> * to this file.
>>> + cancel_delayed_work(&vpu->watchdog_work);
>> drivers/media/platform/verisilicon/hantro_drv.c: In function ‘hantro_release’:
>> drivers/media/platform/verisilicon/hantro_drv.c:604:30: error: ‘vpu’ undeclared (first use in this function); did you mean ‘fpu’?
>> 604 | cancel_delayed_work(&vpu->watchdog_work);
>> | ^~~
>> | fpu
>> drivers/media/platform/verisilicon/hantro_drv.c:604:30: note: each undeclared identifier is reported only once for each function it appears in
>> You clearly didn't compile this patch!
> Sorry for my mistake. I was hurried to report the issue and discuss
> with developer to confirm it . I'll complete it and test it locally.
Was this UAF actually observed, or is it theoretical?
> Best regards,
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