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SubjectRe: [PATCH v3] media: rga: fix NULL pointer dereferences, use-after-free, memory leak
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On 14/03/2019 05:03, 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>

Reviewed-by: Steven Price <steven.price@arm.com>

Yes, that looks like it solves the issues with the clean up - thanks for
reworking it!

> ---
> 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;
> + }
>
> 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);

Minor comment: free_pages accepts a NULL pointer (or more precisely 0,
since it takes an unsigned long), it just returns having done nothing.
So there isn't actually any harm in calling free_pages unconditionally
in the error path (since rga is initialised to all zeros). You can save
a couple of labels in the error path using that trick.

Thanks,

Steve

> +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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