Re: [PATCH v3] media: rga: fix NULL pointer dereferences, use-after-free, memory leak

[Kangjie Lu]

On 3/28/19 9:47 AM, Hans Verkuil wrote:
> Hi Kangjie,
>
> Unfortunately there are more issues with the cleanup sequence in
> this probe function:
>
> On 3/14/19 6:03 AM, Kangjie Lu wrote:
> > 1. dma_alloc_attrs, __get_free_pages can fail and return NULL.
> > Further uses of their return values lead to NULL pointer
> > dereferences
> >
> > 2. In the error-handling path, video_unregister_device uses
> > "rga->vfd" which has been freed by video_device_release
> >
> > 3. The error handling for v4l2_m2m_init and video_register_device
> > has memory-leak issues
> >
> > The patch fixes the above issues.
> >
> > Signed-off-by: Kangjie Lu <kjlu@xxxxxxx>
> > ---
> >   drivers/media/platform/rockchip/rga/rga.c | 26 ++++++++++++++++++++---
> >   1 file changed, 23 insertions(+), 3 deletions(-)
> >
> > diff --git a/drivers/media/platform/rockchip/rga/rga.c b/drivers/media/platform/rockchip/rga/rga.c
> > index 5c653287185f..468365ceb99d 100644
> > --- a/drivers/media/platform/rockchip/rga/rga.c
> > +++ b/drivers/media/platform/rockchip/rga/rga.c
> > @@ -889,11 +889,24 @@ static int rga_probe(struct platform_device *pdev)
> >   	rga->cmdbuf_virt = dma_alloc_attrs(rga->dev, RGA_CMDBUF_SIZE,
> >   					   &rga->cmdbuf_phy, GFP_KERNEL,
> >   					   DMA_ATTR_WRITE_COMBINE);
> > +	if (!rga->cmdbuf_virt) {
> > +		ret = -ENOMEM;
> > +		goto unreg_video_dev;
> Actually, the unreg_video_dev label makes no sense: if the video device
> is successfully registered, then probe() returns 0. So you never need to
> unregister the video device again. You *do* need to release it with
> video_device_release().
>
> So this should be a goto rel_vdev.
>
> And the cleanup sequence at the end also fails to call v4l2_m2m_release().
>
> Can you make v4?


Thanks for the feedback. Will send a v4.


> Thanks!
>
> 	Hans
>
> > +	}
> >   
> >   	rga->src_mmu_pages =
> >   		(unsigned int *)__get_free_pages(GFP_KERNEL | __GFP_ZERO, 3);
> > +	if (!rga->src_mmu_pages) {
> > +		ret = -ENOMEM;
> > +		goto free_dma_attrs;
> > +	}
> > +
> >   	rga->dst_mmu_pages =
> >   		(unsigned int *)__get_free_pages(GFP_KERNEL | __GFP_ZERO, 3);
> > +	if (!rga->dst_mmu_pages) {
> > +		ret = -ENOMEM;
> > +		goto free_dst_pages;
> > +	}
> >   
> >   	def_frame.stride = (def_frame.width * def_frame.fmt->depth) >> 3;
> >   	def_frame.size = def_frame.stride * def_frame.height;
> > @@ -901,7 +914,7 @@ static int rga_probe(struct platform_device *pdev)
> >   	ret = video_register_device(vfd, VFL_TYPE_GRABBER, -1);
> >   	if (ret) {
> >   		v4l2_err(&rga->v4l2_dev, "Failed to register video device\n");
> > -		goto rel_vdev;
> > +		goto free_pages;
> >   	}
> >   
> >   	v4l2_info(&rga->v4l2_dev, "Registered %s as /dev/%s\n",
> > @@ -909,10 +922,17 @@ static int rga_probe(struct platform_device *pdev)
> >   
> >   	return 0;
> >   
> > -rel_vdev:
> > -	video_device_release(vfd);
> > +free_pages:
> > +	free_pages((unsigned long)rga->src_mmu_pages, 3);
> > +free_dst_pages:
> > +	free_pages((unsigned long)rga->dst_mmu_pages, 3);
> > +free_dma_attrs:
> > +	dma_free_attrs(rga->dev, RGA_CMDBUF_SIZE, rga->cmdbuf_virt,
> > +		       rga->cmdbuf_phy,
> > +		       DMA_ATTR_WRITE_COMBINE);
> >   unreg_video_dev:
> >   	video_unregister_device(rga->vfd);
> > +	video_device_release(vfd);
> >   unreg_v4l2_dev:
> >   	v4l2_device_unregister(&rga->v4l2_dev);
> >   err_put_clk: