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SubjectRe: [PATCH v3] media: rga: fix NULL pointer dereferences, use-after-free, memory leak
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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@umn.edu>
> ---
> 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!

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:
>

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