The video_device_release() frees the "vfd" pointer so passing it to
video_unregister_device() on the next line results in a use after free.
Calling video_unregister_device() on a device that hasn't been
registered is supposed to be a no-op so that can be removed. The paths
with to goto unreg_video_dev have a memory leak and should be updated to
goto rel_vdev instead.
Fixes: f7e7b48e6d79 ("[media] rockchip/rga: v4l2 m2m support")
Signed-off-by: Dan Carpenter <[email protected]>
---
drivers/media/platform/rockchip/rga/rga.c | 6 ++----
1 file changed, 2 insertions(+), 4 deletions(-)
diff --git a/drivers/media/platform/rockchip/rga/rga.c b/drivers/media/platform/rockchip/rga/rga.c
index bf3fd71ec3af..37f7fd060c38 100644
--- a/drivers/media/platform/rockchip/rga/rga.c
+++ b/drivers/media/platform/rockchip/rga/rga.c
@@ -863,12 +863,12 @@ static int rga_probe(struct platform_device *pdev)
if (IS_ERR(rga->m2m_dev)) {
v4l2_err(&rga->v4l2_dev, "Failed to init mem2mem device\n");
ret = PTR_ERR(rga->m2m_dev);
- goto unreg_video_dev;
+ goto rel_vdev;
}
ret = pm_runtime_resume_and_get(rga->dev);
if (ret < 0)
- goto unreg_video_dev;
+ goto rel_vdev;
rga->version.major = (rga_read(rga, RGA_VERSION_INFO) >> 24) & 0xFF;
rga->version.minor = (rga_read(rga, RGA_VERSION_INFO) >> 20) & 0x0F;
@@ -904,8 +904,6 @@ static int rga_probe(struct platform_device *pdev)
rel_vdev:
video_device_release(vfd);
-unreg_video_dev:
- video_unregister_device(rga->vfd);
unreg_v4l2_dev:
v4l2_device_unregister(&rga->v4l2_dev);
err_put_clk:
--
2.30.2
On Fri, Jul 9, 2021 at 2:38 PM Dan Carpenter <[email protected]> wrote:
>
> The video_device_release() frees the "vfd" pointer so passing it to
> video_unregister_device() on the next line results in a use after free.
> Calling video_unregister_device() on a device that hasn't been
> registered is supposed to be a no-op so that can be removed. The paths
> with to goto unreg_video_dev have a memory leak and should be updated to
> goto rel_vdev instead.
>
> Fixes: f7e7b48e6d79 ("[media] rockchip/rga: v4l2 m2m support")
> Signed-off-by: Dan Carpenter <[email protected]>
> ---
> drivers/media/platform/rockchip/rga/rga.c | 6 ++----
> 1 file changed, 2 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/media/platform/rockchip/rga/rga.c b/drivers/media/platform/rockchip/rga/rga.c
> index bf3fd71ec3af..37f7fd060c38 100644
> --- a/drivers/media/platform/rockchip/rga/rga.c
> +++ b/drivers/media/platform/rockchip/rga/rga.c
> @@ -863,12 +863,12 @@ static int rga_probe(struct platform_device *pdev)
> if (IS_ERR(rga->m2m_dev)) {
> v4l2_err(&rga->v4l2_dev, "Failed to init mem2mem device\n");
> ret = PTR_ERR(rga->m2m_dev);
> - goto unreg_video_dev;
> + goto rel_vdev;
> }
>
> ret = pm_runtime_resume_and_get(rga->dev);
> if (ret < 0)
> - goto unreg_video_dev;
> + goto rel_vdev;
>
> rga->version.major = (rga_read(rga, RGA_VERSION_INFO) >> 24) & 0xFF;
> rga->version.minor = (rga_read(rga, RGA_VERSION_INFO) >> 20) & 0x0F;
> @@ -904,8 +904,6 @@ static int rga_probe(struct platform_device *pdev)
>
> rel_vdev:
> video_device_release(vfd);
> -unreg_video_dev:
> - video_unregister_device(rga->vfd);
> unreg_v4l2_dev:
> v4l2_device_unregister(&rga->v4l2_dev);
> err_put_clk:
From the analysis of rga_probe and rga_remove function, the init and
cleanup functions are in pairs as follows:
pm_runtime_enable(rga->dev);
ret = v4l2_device_register(&pdev->dev, &rga->v4l2_dev);
vfd = video_device_alloc();
rga->m2m_dev = v4l2_m2m_init(&rga_m2m_ops);
rga->cmdbuf_virt = dma_alloc_attrs(rga->dev, RGA_CMDBUF_SIZE,
&rga->cmdbuf_phy, GFP_KERNEL,
DMA_ATTR_WRITE_COMBINE);
rga->src_mmu_pages =
(unsigned int *)__get_free_pages(GFP_KERNEL | __GFP_ZERO, 3);
rga->dst_mmu_pages =
(unsigned int *)__get_free_pages(GFP_KERNEL | __GFP_ZERO, 3);
ret = video_register_device(vfd, VFL_TYPE_VIDEO, -1);
......
video_unregister_device(rga->vfd);
free_pages((unsigned long)rga->src_mmu_pages, 3);
free_pages((unsigned long)rga->dst_mmu_pages, 3);
dma_free_attrs(rga->dev, RGA_CMDBUF_SIZE, rga->cmdbuf_virt,
rga->cmdbuf_phy, DMA_ATTR_WRITE_COMBINE);
v4l2_m2m_release(rga->m2m_dev);
video_device_release(rga->vfd);
v4l2_device_unregister(&rga->v4l2_dev);
pm_runtime_disable(rga->dev);
So I think the error handling code is more complex than this patch. ;(
> --
> 2.30.2
>
On Fri, Jul 09, 2021 at 05:49:26PM +0800, Dongliang Mu wrote:
> On Fri, Jul 9, 2021 at 2:38 PM Dan Carpenter <[email protected]> wrote:
> >
> > The video_device_release() frees the "vfd" pointer so passing it to
> > video_unregister_device() on the next line results in a use after free.
> > Calling video_unregister_device() on a device that hasn't been
> > registered is supposed to be a no-op so that can be removed. The paths
> > with to goto unreg_video_dev have a memory leak and should be updated to
> > goto rel_vdev instead.
> >
> > Fixes: f7e7b48e6d79 ("[media] rockchip/rga: v4l2 m2m support")
> > Signed-off-by: Dan Carpenter <[email protected]>
> > ---
> > drivers/media/platform/rockchip/rga/rga.c | 6 ++----
> > 1 file changed, 2 insertions(+), 4 deletions(-)
> >
> > diff --git a/drivers/media/platform/rockchip/rga/rga.c b/drivers/media/platform/rockchip/rga/rga.c
> > index bf3fd71ec3af..37f7fd060c38 100644
> > --- a/drivers/media/platform/rockchip/rga/rga.c
> > +++ b/drivers/media/platform/rockchip/rga/rga.c
> > @@ -863,12 +863,12 @@ static int rga_probe(struct platform_device *pdev)
> > if (IS_ERR(rga->m2m_dev)) {
> > v4l2_err(&rga->v4l2_dev, "Failed to init mem2mem device\n");
> > ret = PTR_ERR(rga->m2m_dev);
> > - goto unreg_video_dev;
> > + goto rel_vdev;
> > }
> >
> > ret = pm_runtime_resume_and_get(rga->dev);
> > if (ret < 0)
> > - goto unreg_video_dev;
> > + goto rel_vdev;
> >
> > rga->version.major = (rga_read(rga, RGA_VERSION_INFO) >> 24) & 0xFF;
> > rga->version.minor = (rga_read(rga, RGA_VERSION_INFO) >> 20) & 0x0F;
> > @@ -904,8 +904,6 @@ static int rga_probe(struct platform_device *pdev)
> >
> > rel_vdev:
> > video_device_release(vfd);
> > -unreg_video_dev:
> > - video_unregister_device(rga->vfd);
> > unreg_v4l2_dev:
> > v4l2_device_unregister(&rga->v4l2_dev);
> > err_put_clk:
>
> >From the analysis of rga_probe and rga_remove function, the init and
> cleanup functions are in pairs as follows:
>
Yeah. You're right. It's leaky. This is like the stuff Christophe
Jaillet has been working on.
This is also slightly complicated because what about if the call to
device_register() fails inside video_register_device()? In that case
we're not allowed to call video_device_release(). I think the way
people deal with that is because device_register() never fails in real
life so let's ignore that possibility.
I sort of hate device_register() because it introduces a lot of bugs
like this which don't affect real life. Inside the __video_register_device()
function itself we just ignore errors from video_register_media_controller()
because there is no possible way to handle it in a bug free way. Again,
it's not a bug which is going to affect real life, but it's just
frustrating to not be able to write code which is correct in a technical
sense.
Ah well... Fine. I'll resend.
regards,
dan carpenter