Messages in this thread Patch in this message | | | Subject | Re: [PATCH v2] media:exynos4-is: Fix a use after free in isp_video_release | From | Sylwester Nawrocki <> | Date | Tue, 27 Apr 2021 12:36:48 +0200 |
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On 27.04.2021 08:02, Lv Yunlong wrote: > In isp_video_release, file->private_data is freed via > _vb2_fop_release()->v4l2_fh_release(). But the freed > file->private_data is still used in v4l2_fh_is_singular_file() > ->v4l2_fh_is_singular(file->private_data), which is a use > after free bug. > > My patch set file->private_data to NULL after _vb2_fop_release() > to avoid the use after free. > > Fixes: 34947b8aebe3f ("[media] exynos4-is: Add the FIMC-IS ISP capture DMA driver") > Signed-off-by: Lv Yunlong <lyl2019@mail.ustc.edu.cn> > --- > drivers/media/platform/exynos4-is/fimc-isp-video.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > diff --git a/drivers/media/platform/exynos4-is/fimc-isp-video.c b/drivers/media/platform/exynos4-is/fimc-isp-video.c > index 612b9872afc8..2e04589068b4 100644 > --- a/drivers/media/platform/exynos4-is/fimc-isp-video.c > +++ b/drivers/media/platform/exynos4-is/fimc-isp-video.c > @@ -315,7 +315,8 @@ static int isp_video_release(struct file *file) > } > > _vb2_fop_release(file, NULL); > - > + file->private_data = NULL;
> if (v4l2_fh_is_singular_file(file)) { > fimc_pipeline_call(&ivc->ve, close); >
Thank you for the patch. To ensure the pipeline stop call is done only when the last file handle is released we would need something as below.
--------8<--------- diff --git a/drivers/media/platform/exynos4-is/fimc-isp-video.c b/drivers/media/platform/exynos4-is/fimc-isp-video.c index 612b9872afc8..3335fec509cb 100644 --- a/drivers/media/platform/exynos4-is/fimc-isp-video.c +++ b/drivers/media/platform/exynos4-is/fimc-isp-video.c @@ -306,17 +306,20 @@ static int isp_video_release(struct file *file) struct fimc_is_video *ivc = &isp->video_capture; struct media_entity *entity = &ivc->ve.vdev.entity; struct media_device *mdev = entity->graph_obj.mdev; + bool is_singular_file;
mutex_lock(&isp->video_lock);
- if (v4l2_fh_is_singular_file(file) && ivc->streaming) { + is_singular_file = v4l2_fh_is_singular_file(file); + + if (is_singular_file && ivc->streaming) { media_pipeline_stop(entity); ivc->streaming = 0; }
_vb2_fop_release(file, NULL);
- if (v4l2_fh_is_singular_file(file)) { + if (is_singular_file) { fimc_pipeline_call(&ivc->ve, close);
mutex_lock(&mdev->graph_mutex); --------8<--------- Regards, Sylwester
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