2020-02-28 09:23:59

by Dan Carpenter

Subject: [PATCH] drm: prevent a harmless integer overflow in drm_legacy_sg_alloc()

There is an integer overflow when we round up to PAGE_SIZE, but it's
harmless because we never re-use "request->size" for anything meaningful.

Signed-off-by: Dan Carpenter <[email protected]>
---
This code predates git.

drivers/gpu/drm/drm_scatter.c | 3 +++
1 file changed, 3 insertions(+)

diff --git a/drivers/gpu/drm/drm_scatter.c b/drivers/gpu/drm/drm_scatter.c
index d5c386154246..ca520028b2cb 100644
--- a/drivers/gpu/drm/drm_scatter.c
+++ b/drivers/gpu/drm/drm_scatter.c
@@ -99,6 +99,9 @@ int drm_legacy_sg_alloc(struct drm_device *dev, void *data,
if (!drm_core_check_feature(dev, DRIVER_SG))
return -EOPNOTSUPP;

+ if (request->size > SIZE_MAX - PAGE_SIZE)
+ return -EINVAL;
+
if (dev->sg)
return -EINVAL;

--
2.11.0

2020-02-28 23:41:43

by Daniel Vetter

Subject: Re: [PATCH] drm: prevent a harmless integer overflow in drm_legacy_sg_alloc()

On Fri, Feb 28, 2020 at 12:23:21PM +0300, Dan Carpenter wrote:
> There is an integer overflow when we round up to PAGE_SIZE, but it's
> harmless because we never re-use "request->size" for anything meaningful.
>
> Signed-off-by: Dan Carpenter <[email protected]>
> ---
> This code predates git.

Also not compiled without CONFIG_DRM_LEGACY, which we tell everyone is to
enable the root holes in drm :-)

Thanks for your patch, queued in drm-misc-next.
-Daniel

>
> drivers/gpu/drm/drm_scatter.c | 3 +++
> 1 file changed, 3 insertions(+)
>
> diff --git a/drivers/gpu/drm/drm_scatter.c b/drivers/gpu/drm/drm_scatter.c
> index d5c386154246..ca520028b2cb 100644
> --- a/drivers/gpu/drm/drm_scatter.c
> +++ b/drivers/gpu/drm/drm_scatter.c
> @@ -99,6 +99,9 @@ int drm_legacy_sg_alloc(struct drm_device *dev, void *data,
> if (!drm_core_check_feature(dev, DRIVER_SG))
> return -EOPNOTSUPP;
>
> + if (request->size > SIZE_MAX - PAGE_SIZE)
> + return -EINVAL;
> +
> if (dev->sg)
> return -EINVAL;
>
> --
> 2.11.0
>

--
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch