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 sets file->private_data to NULL after _vb2_fop_release()
to avoid the use after free, and uses a variable 'is_singular_file'
to keep the original function unchanged.
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 | 8 ++++++--
1 file changed, 6 insertions(+), 2 deletions(-)
diff --git a/drivers/media/platform/exynos4-is/fimc-isp-video.c b/drivers/media/platform/exynos4-is/fimc-isp-video.c
index 612b9872afc8..c07dcb0bccc2 100644
--- a/drivers/media/platform/exynos4-is/fimc-isp-video.c
+++ b/drivers/media/platform/exynos4-is/fimc-isp-video.c
@@ -306,17 +306,21 @@ 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);
+ file->private_data = NULL;
- if (v4l2_fh_is_singular_file(file)) {
+ if (is_singular_file) {
fimc_pipeline_call(&ivc->ve, close);
mutex_lock(&mdev->graph_mutex);
--
2.25.1
On 27.04.2021 15:27, 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 sets file->private_data to NULL after _vb2_fop_release()
> to avoid the use after free, and uses a variable 'is_singular_file'
> to keep the original function unchanged.
>
> Fixes: 34947b8aebe3f ("[media] exynos4-is: Add the FIMC-IS ISP capture DMA driver")
> Signed-off-by: Lv Yunlong <[email protected]>
Thanks,
Reviewed-by: Sylwester Nawrocki <[email protected]>
Hi Lv Yunlong,
On 27/04/2021 15:27, 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 sets file->private_data to NULL after _vb2_fop_release()
> to avoid the use after free, and uses a variable 'is_singular_file'
> to keep the original function unchanged.
Actually, it is the use of 'is_singular_file' that fixes the bug,
the 'file->private_data = NULL;' is unnecessary here.
That said, it would be a really good idea if in a separate patch you
make v4l2_fh_release() more robust by setting filp->private_data to
NULL after the kfree(fh).
Regards,
Hans
>
> 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 | 8 ++++++--
> 1 file changed, 6 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/media/platform/exynos4-is/fimc-isp-video.c b/drivers/media/platform/exynos4-is/fimc-isp-video.c
> index 612b9872afc8..c07dcb0bccc2 100644
> --- a/drivers/media/platform/exynos4-is/fimc-isp-video.c
> +++ b/drivers/media/platform/exynos4-is/fimc-isp-video.c
> @@ -306,17 +306,21 @@ 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);
> + file->private_data = NULL;
>
> - if (v4l2_fh_is_singular_file(file)) {
> + if (is_singular_file) {
> fimc_pipeline_call(&ivc->ve, close);
>
> mutex_lock(&mdev->graph_mutex);
>
> -----原始邮件-----
> 发件人: "Hans Verkuil" <[email protected]>
> 发送时间: 2021-05-05 17:31:04 (星期三)
> 收件人: "Lv Yunlong" <[email protected]>, [email protected], [email protected], [email protected]
> 抄送: [email protected], [email protected], [email protected], [email protected]
> 主题: Re: [PATCH v3] media:exynos4-is: Fix a use after free in isp_video_release
>
> Hi Lv Yunlong,
>
> On 27/04/2021 15:27, 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 sets file->private_data to NULL after _vb2_fop_release()
> > to avoid the use after free, and uses a variable 'is_singular_file'
> > to keep the original function unchanged.
>
> Actually, it is the use of 'is_singular_file' that fixes the bug,
> the 'file->private_data = NULL;' is unnecessary here.
>
> That said, it would be a really good idea if in a separate patch you
> make v4l2_fh_release() more robust by setting filp->private_data to
> NULL after the kfree(fh).
>
> Regards,
>
> Hans
>
> >
> > 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 | 8 ++++++--
> > 1 file changed, 6 insertions(+), 2 deletions(-)
> >
> > diff --git a/drivers/media/platform/exynos4-is/fimc-isp-video.c b/drivers/media/platform/exynos4-is/fimc-isp-video.c
> > index 612b9872afc8..c07dcb0bccc2 100644
> > --- a/drivers/media/platform/exynos4-is/fimc-isp-video.c
> > +++ b/drivers/media/platform/exynos4-is/fimc-isp-video.c
> > @@ -306,17 +306,21 @@ 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);
> > + file->private_data = NULL;
> >
> > - if (v4l2_fh_is_singular_file(file)) {
> > + if (is_singular_file) {
> > fimc_pipeline_call(&ivc->ve, close);
> >
> > mutex_lock(&mdev->graph_mutex);
> >
>
Ok, thanks for your suggestion.
Do you means i need submit a new path to set filp->private_data = NULL
after kfree(fh) in v4l2_fh_release() ?
Lv Yunlong
On 06/05/2021 09:19, [email protected] wrote:
>
>
>
>> -----原始邮件-----
>> 发件人: "Hans Verkuil" <[email protected]>
>> 发送时间: 2021-05-05 17:31:04 (星期三)
>> 收件人: "Lv Yunlong" <[email protected]>, [email protected], [email protected], [email protected]
>> 抄送: [email protected], [email protected], [email protected], [email protected]
>> 主题: Re: [PATCH v3] media:exynos4-is: Fix a use after free in isp_video_release
>>
>> Hi Lv Yunlong,
>>
>> On 27/04/2021 15:27, 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 sets file->private_data to NULL after _vb2_fop_release()
>>> to avoid the use after free, and uses a variable 'is_singular_file'
>>> to keep the original function unchanged.
>>
>> Actually, it is the use of 'is_singular_file' that fixes the bug,
>> the 'file->private_data = NULL;' is unnecessary here.
>>
>> That said, it would be a really good idea if in a separate patch you
>> make v4l2_fh_release() more robust by setting filp->private_data to
>> NULL after the kfree(fh).
>>
>> Regards,
>>
>> Hans
>>
>>>
>>> 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 | 8 ++++++--
>>> 1 file changed, 6 insertions(+), 2 deletions(-)
>>>
>>> diff --git a/drivers/media/platform/exynos4-is/fimc-isp-video.c b/drivers/media/platform/exynos4-is/fimc-isp-video.c
>>> index 612b9872afc8..c07dcb0bccc2 100644
>>> --- a/drivers/media/platform/exynos4-is/fimc-isp-video.c
>>> +++ b/drivers/media/platform/exynos4-is/fimc-isp-video.c
>>> @@ -306,17 +306,21 @@ 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);
>>> + file->private_data = NULL;
>>>
>>> - if (v4l2_fh_is_singular_file(file)) {
>>> + if (is_singular_file) {
>>> fimc_pipeline_call(&ivc->ve, close);
>>>
>>> mutex_lock(&mdev->graph_mutex);
>>>
>>
>
>
> Ok, thanks for your suggestion.
>
> Do you means i need submit a new path to set filp->private_data = NULL
> after kfree(fh) in v4l2_fh_release() ?
Yes, so one updated patch for fimc-isp-video.c and a second patch for v4l2-fh.c.
Regards,
Hans
>
> Lv Yunlong
>