Re: [RESEND PATCH] media: mtk-jpeg: Fix use after free bug due to uncanceled work

From: Zheng Hacker
Date: Wed Jun 14 2023 - 22:58:40 EST

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In reply to: Kyrie Wu (吴晗): "Re: [RESEND PATCH] media: mtk-jpeg: Fix use after free bug due to uncanceled work"
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Hi Kyrie,

Thanks for your kind reminder. I'll write the patch as soon as I can.

Best regards,
Zheng Wang

Kyrie Wu (吴晗) <Kyrie.Wu@xxxxxxxxxxxx> 于2023年6月15日周四 10:40写道：
>
> On Mon, 2023-05-15 at 10:57 +0800, Zheng Hacker wrote:
> > External email : Please do not click links or open attachments until
> > you have verified the sender or the content.
> >
> >
> > Hi Kyrie,
> >
> > I think your analysis is right, I'll make the change in the next
> > version.
> >
> > Best regards,
> > Zheng
> >
> Dear Zheng,
>
> Could you please update the next version at any convenient time?
>
> Thanks.
>
> Bset Regards,
> Kyrie.
>
> > Kyrie Wu (吴晗) <Kyrie.Wu@xxxxxxxxxxxx> 于2023年5月12日周五 09:24写道：
> > >
> > > On Tue, 2023-03-14 at 11:37 +0800, Zheng Hacker wrote:
> > > > Kyrie Wu (吴晗) <Kyrie.Wu@xxxxxxxxxxxx> 于2023年3月14日周二 10:49写道：
> > > > >
> > > > > On Thu, 2023-03-09 at 15:31 +0800, Zheng Hacker wrote:
> > > > > > Dear Kyrie,
> > > > > >
> > > > > > Guenter gave some advice about this issue in [1]. As we are
> > > > > > not
> > > > > > familiar with the code here, could you please see if the bug
> > > > > > really
> > > > > > exists?
> > > > > >
> > > > > > [1]
> > > > > >
> > >
> > >
> https://lore.kernel.org/all/e03134f9-9433-ab6b-170a-8ce752fccdeb@xxxxxxxxxxxx/
> > > > > >
> > > > > > Best regards,
> > > > > > Zheng
> > > > >
> > > > > Dear zheng,
> > > > >
> > > > > I have no more questions for your patch, thank you for your
> > > > > contribution to mtk jpeg driver.
> > > > >
> > > >
> > > > Thanks for your detailed review and explanation about the code. I
> > > > have
> > > > learned a lot
> > > > from it. Have a nice day :)
> > > >
> > > > Best regards,
> > > > Zheng
> > >
> > > Dear Zheng,
> > >
> > > I think that cancel_delayed_work, added in remove function, should
> > > change to cancel_delayed_work_sync to solve UAF. The corresponding
> > > operation flow is shown as follow:
> > > CPU0 CPU1
> > > |mtk_jpeg_job_timeout_work
> > > mtk_jpeg_remove |
> > > cancel_delayed_work |
> > > v4l2_m2m_release |
> > > kfree(m2m_dev); |
> > > |
> > > | v4l2_m2m_get_curr_priv
> > > | m2m_dev->curr_ctx //use
> > >
> > > If cancel_delayed_work is called in async mode like above, and the
> > > m2m_dev is freed. But it is used in mtk_jpeg_job_timeout_work, this
> > > calling may cause UAF.
> > >
> > > Thanks.
> > > >
> > > > > >
> > > > > >
> > > > > >
> > > > > > Zheng Hacker <hackerzheng666@xxxxxxxxx> 于2023年3月8日周三 17:11写道：
> > > > > > >
> > > > > > > Dear Kyrie,
> > > > > > >
> > > > > > > Sorry for my misunderstanding. I've seen the timeout worker
> > > > > > > is
> > > > > > > bound
> > > > > > > with mtk_jpegdec_timeout_work rather than
> > > > > > > mtk_jpeg_job_timeout_work.So
> > > > > > > the competition won't happen.
> > > > > > >
> > > > > > > Back to the beginning scene, I still don't know if it's a
> > > > > > > UAF
> > > > > > > issue
> > > > > > > or
> > > > > > > not. The normal schedule is very strong to me. If we can
> > > > > > > call
> > > > > > > mtk_jpeg_remove directly without calling mtk_jpeg_release,
> > > > > > > The UAF is still possible. Otherwis, I think it's safe
> > > > > > > here.
> > > > > > >
> > > > > > > Best regards,
> > > > > > > Zheng
> > > > > > >
> > > > > > > Kyrie Wu (吴晗) <Kyrie.Wu@xxxxxxxxxxxx> 于2023年3月8日周三 15:39写道：
> > > > > > > >
> > > > > > > > On Wed, 2023-03-08 at 14:10 +0800, Zheng Hacker wrote:
> > > > > > > > > Hi Kyrie,
> > > > > > > > >
> > > > > > > > > After reviewing the code, I found anothe possible code
> > > > > > > > > path. As
> > > > > > > > > I am
> > > > > > > > > not familiar with the module. It has high possibility
> > > > > > > > > it's
> > > > > > > > > wrong.
> > > > > > > > > Could please help me check this? Very much appreciated
> > > > > > > > > for
> > > > > > > > > your
> > > > > > > > > valuable time.
> > > > > > > > >
> > > > > > > > > In summary, mtk_jpegdec_worker was set in mtk_jpeg_open
> > > > > > > > > and
> > > > > > > > > started
> > > > > > > > > in
> > > > > > > > > mtk_jpeg_multicore_dec_device_run, which made it
> > > > > > > > > running on
> > > > > > > > > cpu1.
> > > > > > > > > Inside the mtk_jpeg_multicore_dec_device_run, it will
> > > > > > > > > call
> > > > > > > > > schedule_delayed_work to start the timeout_work, which
> > > > > > > > > will
> > > > > > > > > make it
> > > > > > > > > running on cpu2. Meanwhile, we can call
> > > > > > > > > mtk_jpeg_release to cancel the job. But there might be
> > > > > > > > > a
> > > > > > > > > race
> > > > > > > > > between
> > > > > > > > > mtk_jpegdec_worker and v4l2_m2m_cancel_job. It may call
> > > > > > > > > v4l2_m2m_job_finish too early to wake up the event.
> > > > > > > > > The remove will go on, the other race is as described
> > > > > > > > > earlier.
> > > > > > > > >
> > > > > > > > > cpu0 cpu1 cpu2
> > > > > > > > > (1)->device_run
> > > > > > > > > mtk_jpeg_multicore
> > > > > > > > > _dec_device_run
> > > > > > > > > queue_work
> > > > > > > > > (jpeg->workqueue,
> > > > > > > > > &ctx->jpeg_work);
> > > > > > > > > (2)mtk_jpegdec_worker
> > > > > > > > > (3)mtk_jpeg_release
> > > > > > > > > v4l2_m2m_cancel_job
> > > > > > > > > wait event
> > > > > > > > >
> > > > > > > > > schedule_delayed_work
> > > > > > > > > (4)mtk_jpeg
> > > > > > > > > _job
> > > > > > > > > _tim
> > > > > > > > > eout_w
> > > > > > > > > ork
> > > > > > > > > (5)v4l2_m2m_job_finish
> > > > > > > > > wake up
> > > > > > > > > (6)mtk_jpeg_remove
> > > > > > > > > v4l2_m2m_release
> > > > > > > > > kfree(m2m_dev)
> > > > > > > > > (7)v4l2_m2m
> > > > > > > > > _get
> > > > > > > > > _cur
> > > > > > > > > r_priv
> > > > > > > > >
> > > > > > > >
> > > > > > > > Dear zheng,
> > > > > > > >
> > > > > > > > The mtk_jpeg_multicore_dec_device_run function is used
> > > > > > > > for
> > > > > > > > multi-
> > > > > > > > hw
> > > > > > > > jpeg decoding. Instead of scheduling
> > > > > > > > mtk_jpeg_job_timeout_work,
> > > > > > > > mtk_jpegdec_worker is scheduled in this function.
> > > > > > > >
> > > > > > > > The mtk_jpeg_dec_device_run function is used for single
> > > > > > > > hw
> > > > > > > > jpeg
> > > > > > > > decoding, which schedules mtk_jpeg_job_timeout_work.
> > > > > > > >
> > > > > > > > A driver is either a single hw driver or a multi-hw
> > > > > > > > driver
> > > > > > > > and
> > > > > > > > cannot
> > > > > > > > represent both at the same time.
> > > > > > > > mtk_jpeg_job_timeout_work and mtk_jpegdec_worker cannot
> > > > > > > > be
> > > > > > > > scheduled at
> > > > > > > > the same time.
> > > > > > > > So mtk_jpeg_job_timeout_work calls v4l2_m2m_job_finish
> > > > > > > > would
> > > > > > > > not
> > > > > > > > cause
> > > > > > > > competition between the mtk_jpegdec_worker and
> > > > > > > > v4l2_m2m_cancel_job.
> > > > > > > >
> > > > > > > > Regards,
> > > > > > > > Kyrie.
> > > > > > > >
> > > > > > > >
> > > > > > > > > Kyrie Wu (吴晗) <Kyrie.Wu@xxxxxxxxxxxx> 于2023年3月8日周三
> > > > > > > > > 11:32写道：
> > > > > > > > > >
> > > > > > > > > > On Wed, 2023-03-08 at 10:20 +0800, Zheng Hacker
> > > > > > > > > > wrote:
> > > > > > > > > > > Hi Kyrie,
> > > > > > > > > > >
> > > > > > > > > > > Thank you for your careful analysis and response. I
> > > > > > > > > > > still
> > > > > > > > > > > have
> > > > > > > > > > > some
> > > > > > > > > > > areas that I don't quite understand and would like
> > > > > > > > > > > to
> > > > > > > > > > > ask
> > > > > > > > > > > for
> > > > > > > > > > > clarification. That is, how do the function
> > > > > > > > > > > pointers
> > > > > > > > > > > for
> > > > > > > > > > > stop
> > > > > > > > > > > streaming, initialized as
> > > > > > > > > > > mtk_jpeg_enc_stop_streaming
> > > > > > > > > > > and
> > > > > > > > > > > mtk_jpeg_dec_stop_streaming, ensure that the worker
> > > > > > > > > > > is
> > > > > > > > > > > canceled?
> > > > > > > > > > > I
> > > > > > > > > > > would greatly appreciate your response.
> > > > > > > > > > >
> > > > > > > > > > > Best regards,
> > > > > > > > > > > Zheng
> > > > > > > > > >
> > > > > > > > > > Dear zheng,
> > > > > > > > > >
> > > > > > > > > > For stop streaming, what I mean is that stoppping
> > > > > > > > > > jpeg
> > > > > > > > > > decoding or
> > > > > > > > > > encoding.
> > > > > > > > > > Ok, let me introduce the sw flow of stop streaming:
> > > > > > > > > > Firstly, the app will call v4l2_m2m_ioctl_streamoff,
> > > > > > > > > > which
> > > > > > > > > > will
> > > > > > > > > > call
> > > > > > > > > > v4l2_m2m_cancel_job, if it finds a job running(as you
> > > > > > > > > > note,
> > > > > > > > > > cpu1 is
> > > > > > > > > > running), it will wait event, the event is wake up by
> > > > > > > > > > v4l2_m2m_job_finish function. And v4l2_m2m_job_finish
> > > > > > > > > > is
> > > > > > > > > > called by
> > > > > > > > > > jpeg
> > > > > > > > > > dec/enc irq handler, which means that the waitting
> > > > > > > > > > would
> > > > > > > > > > result mtk
> > > > > > > > > > hw
> > > > > > > > > > to finish dec/enc, irq will occur and irq handler
> > > > > > > > > > would
> > > > > > > > > > cancel
> > > > > > > > > > timeout
> > > > > > > > > > worker. The follow is shown as blow.
> > > > > > > > > > v4l2_m2m_ioctl_streamoff
> > > > > > > > > > v4l2_m2m_cancel_job mtk_jpeg_enc_ir
> > > > > > > > > > q/mt
> > > > > > > > > > k_jp
> > > > > > > > > > eg_dec
> > > > > > > > > > _irq
> > > > > > > > > > wait evnet <------ wake up ------
> > > > > > > > > > v4l2_m2m_job_finish
> > > > > > > > > > cancel
> > > > > > > > > > timeout
> > > > > > > > > > work
> > > > > > > > > >
> > > > > > > > > > As mentioned above, if it is normal stop streaming
> > > > > > > > > > action,
> > > > > > > > > > there
> > > > > > > > > > will
> > > > > > > > > > be no happen that the timeout worker does not
> > > > > > > > > > canceled.
> > > > > > > > > >
> > > > > > > > > > But if mtk_jpeg_remove is called directly without
> > > > > > > > > > above
> > > > > > > > > > flow,
> > > > > > > > > > it
> > > > > > > > > > would
> > > > > > > > > > cause lots of issues.
> > > > > > > > > >
> > > > > > > > > > Regards,
> > > > > > > > > > Kyrie.
> > > > > > > > > > >
> > > > > > > > > > > Kyrie Wu (吴晗) <Kyrie.Wu@xxxxxxxxxxxx> 于2023年3月8日周三
> > > > > > > > > > > 10:02写道：
> > > > > > > > > > > >
> > > > > > > > > > > > On Tue, 2023-03-07 at 23:03 +0800, Zheng Hacker
> > > > > > > > > > > > wrote:
> > > > > > > > > > > > > The timer function was set in mtk_jpeg_probe
> > > > > > > > > > > > > with
> > > > > > > > > > > > > mtk_jpeg_job_timeout_work function.
> > > > > > > > > > > > > And the worker is started in
> > > > > > > > > > > > > mtk_jpeg_dec_device_run.
> > > > > > > > > > > > > There are two functions (mtk_jpeg_enc_irq and
> > > > > > > > > > > > > mtk_jpeg_dec_irq)
> > > > > > > > > > > > > which
> > > > > > > > > > > > > may cancel the worker.
> > > > > > > > > > > > > They are used as IRQ handler function which is
> > > > > > > > > > > > > saved as
> > > > > > > > > > > > > function
> > > > > > > > > > > > > pointer in a variable.
> > > > > > > > > > > > > In mtk_jpeg_probe, they are registered by
> > > > > > > > > > > > > devm_request_irq:
> > > > > > > > > > > > >
> > > > > > > > > > > > > ret = devm_request_irq(&pdev->dev,
> > > > > > > > > > > > > jpeg_irq,
> > > > > > > > > > > > > jpeg->variant->irq_handler,
> > > > > > > > > > > > > 0,
> > > > > > > > > > > > > pdev->name, jpeg);
> > > > > > > > > > > > > if (ret) {
> > > > > > > > > > > > > dev_err(&pdev->dev, "Failed to request
> > > > > > > > > > > > > jpeg_irq
> > > > > > > > > > > > > %d
> > > > > > > > > > > > > (%d)\n",
> > > > > > > > > > > > > jpeg_irq, ret);
> > > > > > > > > > > > > return ret;
> > > > > > > > > > > > > }
> > > > > > > > > > > > >
> > > > > > > > > > > > > However, if we remove the module without
> > > > > > > > > > > > > triggering
> > > > > > > > > > > > > the
> > > > > > > > > > > > > irq,
> > > > > > > > > > > > > the
> > > > > > > > > > > > > worker will never be removed.
> > > > > > > > > > > > >
> > > > > > > > > > > > > As for the schedule, mtk_jpeg_dec_device_run
> > > > > > > > > > > > > and
> > > > > > > > > > > > > mtk_jpeg_enc_device_run will start the worker.
> > > > > > > > > > > > > The schedule invoking is quite complicated. As
> > > > > > > > > > > > > far
> > > > > > > > > > > > > as I
> > > > > > > > > > > > > know,
> > > > > > > > > > > > > the
> > > > > > > > > > > > > invoking chain is as follows:
> > > > > > > > > > > > >
> > > > > > > > > > > > > v4l2_m2m_init->v4l2_m2m_device_run_work-
> > > > > > > > > > > > > > v4l2_m2m_try_run
> > > > > > > > > > > > >
> > > > > > > > > > > > > the v4l2_m2m_device_run_work function is also a
> > > > > > > > > > > > > worker
> > > > > > > > > > > > > which
> > > > > > > > > > > > > is
> > > > > > > > > > > > > set
> > > > > > > > > > > > > in
> > > > > > > > > > > > > v4l2_m2m_init and started in
> > > > > > > > > > > > > v4l2_m2m_schedule_next_job.
> > > > > > > > > > > > >
> > > > > > > > > > > > > Before calling remove function,
> > > > > > > > > > > > > the mtk_jpeg_release
> > > > > > > > > > > > > was
> > > > > > > > > > > > > invoked
> > > > > > > > > > > > > to
> > > > > > > > > > > > > release the related resource.
> > > > > > > > > > > > >
> > > > > > > > > > > > > v4l2_m2m_cancel_job will cancel the job by
> > > > > > > > > > > > > calling
> > > > > > > > > > > > > m2m_dev->m2m_ops->job_abort(m2m_ctx->priv).
> > > > > > > > > > > > >
> > > > > > > > > > > > > But this will only cancel the current queue by
> > > > > > > > > > > > > list_del(&m2m_dev->curr_ctx->queue);
> > > > > > > > > > > > >
> > > > > > > > > > > > > I think this can not cancel the posted task
> > > > > > > > > > > > > mentioned
> > > > > > > > > > > > > before.
> > > > > > > > > > > > > So
> > > > > > > > > > > > > I
> > > > > > > > > > > > > think if mtk_jpeg_job_timeout_work
> > > > > > > > > > > > >
> > > > > > > > > > > > > is working on, and using jpeg->m2m_dev after
> > > > > > > > > > > > > freeing it
> > > > > > > > > > > > > in
> > > > > > > > > > > > > mtk_jpeg_remove, it will cause a UAF bug.
> > > > > > > > > > > > >
> > > > > > > > > > > > > static int mtk_jpeg_release(struct file *file)
> > > > > > > > > > > > > {
> > > > > > > > > > > > > struct mtk_jpeg_dev *jpeg =
> > > > > > > > > > > > > video_drvdata(file);
> > > > > > > > > > > > > struct mtk_jpeg_ctx *ctx =
> > > > > > > > > > > > > mtk_jpeg_fh_to_ctx(file-
> > > > > > > > > > > > > > private_data);
> > > > > > > > > > > > >
> > > > > > > > > > > > > mutex_lock(&jpeg->lock);
> > > > > > > > > > > > > v4l2_ctrl_handler_free(&ctx->ctrl_hdl);
> > > > > > > > > > > > > [1] v4l2_m2m_ctx_release(ctx->fh.m2m_ctx);
> > > > > > > > > > > > > v4l2_fh_del(&ctx->fh);
> > > > > > > > > > > > > v4l2_fh_exit(&ctx->fh);
> > > > > > > > > > > > > kfree(ctx);
> > > > > > > > > > > > > mutex_unlock(&jpeg->lock);
> > > > > > > > > > > > > return 0;
> > > > > > > > > > > > > }
> > > > > > > > > > > > >
> > > > > > > > > > > > > void v4l2_m2m_ctx_release(struct v4l2_m2m_ctx
> > > > > > > > > > > > > *m2m_ctx)
> > > > > > > > > > > > > {
> > > > > > > > > > > > > /* wait until the current context is dequeued
> > > > > > > > > > > > > from
> > > > > > > > > > > > > job_queue */
> > > > > > > > > > > > > [2] v4l2_m2m_cancel_job(m2m_ctx);
> > > > > > > > > > > > >
> > > > > > > > > > > > > vb2_queue_release(&m2m_ctx->cap_q_ctx.q);
> > > > > > > > > > > > > vb2_queue_release(&m2m_ctx->out_q_ctx.q);
> > > > > > > > > > > > >
> > > > > > > > > > > > > kfree(m2m_ctx);
> > > > > > > > > > > > > }
> > > > > > > > > > > > >
> > > > > > > > > > > > > Note that all of this is static analysis, which
> > > > > > > > > > > > > may
> > > > > > > > > > > > > be
> > > > > > > > > > > > > false
> > > > > > > > > > > > > positive.
> > > > > > > > > > > > > Feel free to tell me if there is something I've
> > > > > > > > > > > > > missed.
> > > > > > > > > > > > >
> > > > > > > > > > > > > Regard,
> > > > > > > > > > > > > Zheng
> > > > > > > > > > > >
> > > > > > > > > > > > Dear Zheng,
> > > > > > > > > > > >
> > > > > > > > > > > > You set up an application scenario:
> > > > > > > > > > > > cpu1 is using the mtk-jpeg driver and timeout
> > > > > > > > > > > > work
> > > > > > > > > > > > has
> > > > > > > > > > > > been
> > > > > > > > > > > > scheduled.
> > > > > > > > > > > > At the same time cpu0 wanted to remove the mtk-
> > > > > > > > > > > > jpeg
> > > > > > > > > > > > driver,
> > > > > > > > > > > > which
> > > > > > > > > > > > caused the UAF bug.
> > > > > > > > > > > > I wonder if such an irrational application
> > > > > > > > > > > > scenario
> > > > > > > > > > > > could
> > > > > > > > > > > > exist.
> > > > > > > > > > > > This
> > > > > > > > > > > > scenario, as you described, not only leads to the
> > > > > > > > > > > > problems you
> > > > > > > > > > > > mentioned, but also to output&capture memory
> > > > > > > > > > > > leaks
> > > > > > > > > > > > and
> > > > > > > > > > > > unreleased
> > > > > > > > > > > > resources, such as spinlock.
> > > > > > > > > > > > Typically, if we want to remove the driver, we
> > > > > > > > > > > > firstly do
> > > > > > > > > > > > stop
> > > > > > > > > > > > streaming, which ensures that the worker has been
> > > > > > > > > > > > canceled.
> > > > > > > > > > > > I agree with your changes from the perspective of
> > > > > > > > > > > > strengthening
> > > > > > > > > > > > the
> > > > > > > > > > > > robustness of the driver code.
> > > > > > > > > > > >
> > > > > > > > > > > > Regards,
> > > > > > > > > > > > Kyrie.
> > > > > > > > > > > > >
> > > > > > > > > > > > > Irui Wang (王瑞) <Irui.Wang@xxxxxxxxxxxx>
> > > > > > > > > > > > > 于2023年3月7日周二
> > > > > > > > > > > > > 18:23写道：
> > > > > > > > > > > > > >
> > > > > > > > > > > > > > Dear Angelo and Zheng,
> > > > > > > > > > > > > >
> > > > > > > > > > > > > > Thanks for your patch and comments.
> > > > > > > > > > > > > >
> > > > > > > > > > > > > > Dear Kyrie,
> > > > > > > > > > > > > >
> > > > > > > > > > > > > > Please help to check this, thanks.
> > > > > > > > > > > > > >
> > > > > > > > > > > > > > Best Regards
> > > > > > > > > > > > > >
> > > > > > > > > > > > > > On Tue, 2023-03-07 at 10:49 +0100,
> > > > > > > > > > > > > > AngeloGioacchino
> > > > > > > > > > > > > > Del
> > > > > > > > > > > > > > Regno
> > > > > > > > > > > > > > wrote:
> > > > > > > > > > > > > > > Il 07/03/23 10:27, Zheng Hacker ha scritto:
> > > > > > > > > > > > > > > > Hi,
> > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > Is there anyone who can help with this? I
> > > > > > > > > > > > > > > > can
> > > > > > > > > > > > > > > > provide
> > > > > > > > > > > > > > > > more
> > > > > > > > > > > > > > > > details
> > > > > > > > > > > > > > > > like invoking chain if needed.
> > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > Providing more details is always good.
> > > > > > > > > > > > > > > Please
> > > > > > > > > > > > > > > do.
> > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > Meanwhile, adding Irui Wang to the loop:
> > > > > > > > > > > > > > > he's
> > > > > > > > > > > > > > > doing
> > > > > > > > > > > > > > > mtk-
> > > > > > > > > > > > > > > jpeg.
> > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > Regards,
> > > > > > > > > > > > > > > Angelo
> > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > Thanks,
> > > > > > > > > > > > > > > > Zheng
> > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > Zheng Wang <zyytlz.wz@xxxxxxx>
> > > > > > > > > > > > > > > > 于2023年3月6日周一
> > > > > > > > > > > > > > > > 14:28写道：
> > > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > > In mtk_jpeg_probe, &jpeg-
> > > > > > > > > > > > > > > > > >job_timeout_work
> > > > > > > > > > > > > > > > > is
> > > > > > > > > > > > > > > > > bound
> > > > > > > > > > > > > > > > > with
> > > > > > > > > > > > > > > > > mtk_jpeg_job_timeout_work. Then
> > > > > > > > > > > > > > > > > mtk_jpeg_dec_device_run
> > > > > > > > > > > > > > > > > and mtk_jpeg_enc_device_run may be
> > > > > > > > > > > > > > > > > called
> > > > > > > > > > > > > > > > > to
> > > > > > > > > > > > > > > > > start
> > > > > > > > > > > > > > > > > the
> > > > > > > > > > > > > > > > > work.
> > > > > > > > > > > > > > > > > If we remove the module which will call
> > > > > > > > > > > > > > > > > mtk_jpeg_remove
> > > > > > > > > > > > > > > > > to make cleanup, there may be a
> > > > > > > > > > > > > > > > > unfinished
> > > > > > > > > > > > > > > > > work. The
> > > > > > > > > > > > > > > > > possible sequence is as follows, which
> > > > > > > > > > > > > > > > > will
> > > > > > > > > > > > > > > > > cause a
> > > > > > > > > > > > > > > > > typical UAF bug.
> > > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > > Fix it by canceling the work before
> > > > > > > > > > > > > > > > > cleanup
> > > > > > > > > > > > > > > > > in
> > > > > > > > > > > > > > > > > the
> > > > > > > > > > > > > > > > > mtk_jpeg_remove
> > > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > > CPU0 CPU1
> > > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > > |mtk_jpeg_job_time
> > > > > > > > > > > > > > > > > out_
> > > > > > > > > > > > > > > > > work
> > > > > > > > > > > > > > > > > mtk_jpeg_remove |
> > > > > > > > > > > > > > > > > v4l2_m2m_release |
> > > > > > > > > > > > > > > > > kfree(m2m_dev); |
> > > > > > > > > > > > > > > > > |
> > > > > > > > > > > > > > > > > |
> > > > > > > > > > > > > > > > > v4l2_m2m_get_curr_priv
> > > > > > > > > > > > > > > > > | m2m_dev-
> > > > > > > > > > > > > > > > > >curr_ctx
> > > > > > > > > > > > > > > > > //use
> > > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > > Signed-off-by: Zheng Wang <
> > > > > > > > > > > > > > > > > zyytlz.wz@xxxxxxx>
> > > > > > > > > > > > > > > > > ---
> > > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > > drivers/media/platform/mediatek/jpeg/mt
> > > > > > > > > > > > > > > > > k_jp
> > > > > > > > > > > > > > > > > eg_c
> > > > > > > > > > > > > > > > > ore.c
> > > > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > > 2 +-
> > > > > > > > > > > > > > > > > 1 file changed, 1 insertion(+), 1
> > > > > > > > > > > > > > > > > deletion(-)
> > > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > > diff --git
> > > > > > > > > > > > > > > > > a/drivers/media/platform/mediatek/jpeg/
> > > > > > > > > > > > > > > > > mtk_
> > > > > > > > > > > > > > > > > jpeg
> > > > > > > > > > > > > > > > > _core.
> > > > > > > > > > > > > > > > > c
> > > > > > > > > > > > > > > > > b/drivers/media/platform/mediatek/jpeg/
> > > > > > > > > > > > > > > > > mtk_
> > > > > > > > > > > > > > > > > jpeg
> > > > > > > > > > > > > > > > > _core.
> > > > > > > > > > > > > > > > > c
> > > > > > > > > > > > > > > > > index 969516a940ba..364513e7897e 100644
> > > > > > > > > > > > > > > > > ---
> > > > > > > > > > > > > > > > > a/drivers/media/platform/mediatek/jpeg/
> > > > > > > > > > > > > > > > > mtk_
> > > > > > > > > > > > > > > > > jpeg
> > > > > > > > > > > > > > > > > _core.
> > > > > > > > > > > > > > > > > c
> > > > > > > > > > > > > > > > > +++
> > > > > > > > > > > > > > > > > b/drivers/media/platform/mediatek/jpeg/
> > > > > > > > > > > > > > > > > mtk_
> > > > > > > > > > > > > > > > > jpeg
> > > > > > > > > > > > > > > > > _core.
> > > > > > > > > > > > > > > > > c
> > > > > > > > > > > > > > > > > @@ -1793,7 +1793,7 @@ static int
> > > > > > > > > > > > > > > > > mtk_jpeg_probe(struct
> > > > > > > > > > > > > > > > > platform_device *pdev)
> > > > > > > > > > > > > > > > > static int mtk_jpeg_remove(struct
> > > > > > > > > > > > > > > > > platform_device
> > > > > > > > > > > > > > > > > *pdev)
> > > > > > > > > > > > > > > > > {
> > > > > > > > > > > > > > > > > struct mtk_jpeg_dev *jpeg =
> > > > > > > > > > > > > > > > > platform_get_drvdata(pdev);
> > > > > > > > > > > > > > > > > -
> > > > > > > > > > > > > > > > > + cancel_delayed_work(&jpeg-
> > > > > > > > > > > > > > > > > > job_timeout_work);
> > > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > > pm_runtime_disable(&pdev-
> > > > > > > > > > > > > > > > > >dev);
> > > > > > > > > > > > > > > > > video_unregister_device(jpeg-
> > > > > > > > > > > > > > > > > > vdev);
> > > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > > v4l2_m2m_release(jpeg-
> > > > > > > > > > > > > > > > > >m2m_dev);
> > > > > > > > > > > > > > > > > --
> > > > > > > > > > > > > > > > > 2.25.1
> > > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > >
> > > > > > > > > > > > > > >
> > > > > > > > > > > > > > >

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