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

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