Commit 01fe904c authored May 09, 2021 by Lv Yunlong Committed by Mauro Carvalho Chehab Jun 02, 2021

media: exynos4-is: Fix a use after free in isp_video_release

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 uses a variable 'is_singular_file' to avoid the uaf.
v3: https://lore.kernel.org/patchwork/patch/1419058/



Fixes: 34947b8a ("[media] exynos4-is: Add the FIMC-IS ISP capture DMA driver")
Signed-off-by: Lv Yunlong <lyl2019@mail.ustc.edu.cn>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>

parent f9c2fd3b

drivers/media/platform/exynos4-is/fimc-isp-video.c

+5 −2

Original line number	Diff line number	Diff line
		@@ -305,17 +305,20 @@ 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);