2021-04-27 06:07:16

by Lv Yunlong

Subject: [PATCH v2] 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 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 <[email protected]>
---
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);

--
2.25.1

2021-04-27 10:38:04

by Sylwester Nawrocki

Subject: Re: [PATCH v2] media:exynos4-is: Fix a use after free in isp_video_release

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 <[email protected]>
> ---
> 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

2021-04-27 13:31:05

by Lv Yunlong

Subject: Re: Re: [PATCH v2] media:exynos4-is: Fix a use after free in isp_video_release

> -----原始邮件-----
> 发件人: "Sylwester Nawrocki" <[email protected]>
> 发送时间: 2021-04-27 18:36:48 (星期二)
> 收件人: "Lv Yunlong" <[email protected]>
> 抄送: [email protected], [email protected], [email protected], [email protected], [email protected], [email protected], [email protected]
> 主题: Re: [PATCH v2] media:exynos4-is: Fix a use after free in isp_video_release
>
> 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 <[email protected]>
> > ---
> > 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

Ok, thanks for your review and help.
I have corrected my patch and sent the PATCH v3 for you review again.

Thanks.