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@xxxxxxxxxxxxxxxx>
---
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
