[patch] drm: crtc: integer overflow in drm_property_create_blob()

[patch] drm: crtc: integer overflow in drm_property_create_blob()

[Dan Carpenter]

The size here comes from the user via the ioctl, it is a number between
1-u32max so the addition here could overflow on 32 bit systems.

Fixes: f453ba046074 ('DRM: add mode setting support')
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>

diff --git a/drivers/gpu/drm/drm_crtc.c b/drivers/gpu/drm/drm_crtc.c
index e54660a..627b2d0 100644
--- a/drivers/gpu/drm/drm_crtc.c
+++ b/drivers/gpu/drm/drm_crtc.c
@@ -4107,7 +4107,7 @@ drm_property_create_blob(struct drm_device *dev, size_t length,
 	struct drm_property_blob *blob;
 	int ret;
 
-	if (!length)
+	if (!length || length > ULONG_MAX - sizeof(struct drm_property_blob))
 		return ERR_PTR(-EINVAL);
 
 	blob = kzalloc(sizeof(struct drm_property_blob)+length, GFP_KERNEL);

[patch] drm: crtc: integer overflow in drm_property_create_blob()

[Dan Carpenter]

The size here comes from the user via the ioctl, it is a number between
1-u32max so the addition here could overflow on 32 bit systems.

Fixes: f453ba046074 ('DRM: add mode setting support')
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>

diff --git a/drivers/gpu/drm/drm_crtc.c b/drivers/gpu/drm/drm_crtc.c
index e54660a..627b2d0 100644
--- a/drivers/gpu/drm/drm_crtc.c
+++ b/drivers/gpu/drm/drm_crtc.c
@@ -4107,7 +4107,7 @@ drm_property_create_blob(struct drm_device *dev, size_t length,
 	struct drm_property_blob *blob;
 	int ret;
 
-	if (!length)
+	if (!length || length > ULONG_MAX - sizeof(struct drm_property_blob))
 		return ERR_PTR(-EINVAL);
 
 	blob = kzalloc(sizeof(struct drm_property_blob)+length, GFP_KERNEL);
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Re: [patch] drm: crtc: integer overflow in drm_property_create_blob()

[Daniel Stone]

Hi Dan,

On 29 October 2015 at 13:37, Dan Carpenter <dan.carpenter@oracle.com> wrote:
> The size here comes from the user via the ioctl, it is a number between
> 1-u32max so the addition here could overflow on 32 bit systems.
>
> Fixes: f453ba046074 ('DRM: add mode setting support')
> Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>

Thanks for catching this. I did have a pass through looking for such
issues but couldn't see any. :\

Reviewed-by: Daniel Stone <daniels@collabora.com>
Cc: stable@kernel.org # v4.2

Cheers,
Daniel