2017-03-24 15:37:57

by Vladis Dronov

Subject: [PATCH] drm/vmwgfx: Check check that number of mip levels is above zero in vmw_surface_define_ioctl()

In vmw_surface_define_ioctl(), a num_sizes parameter is assigned a
user-controlled value which is not checked for zero. It is used in
a call to kmalloc() which returns ZERO_SIZE_PTR. Later ZERO_SIZE_PTR
is dereferenced which leads to a GPF and possibly to a kernel panic.
Add the check for zero to avoid this.

Reference: https://bugzilla.redhat.com/show_bug.cgi?id=1435719
Signed-off-by: Vladis Dronov <[email protected]>
---
drivers/gpu/drm/vmwgfx/vmwgfx_surface.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/vmwgfx/vmwgfx_surface.c b/drivers/gpu/drm/vmwgfx/vmwgfx_surface.c
index b445ce9..42840cc 100644
--- a/drivers/gpu/drm/vmwgfx/vmwgfx_surface.c
+++ b/drivers/gpu/drm/vmwgfx/vmwgfx_surface.c
@@ -716,8 +716,8 @@ int vmw_surface_define_ioctl(struct drm_device *dev, void *data,
for (i = 0; i < DRM_VMW_MAX_SURFACE_FACES; ++i)
num_sizes += req->mip_levels[i];

- if (num_sizes > DRM_VMW_MAX_SURFACE_FACES *
- DRM_VMW_MAX_MIP_LEVELS)
+ if (num_sizes <= 0 ||
+ num_sizes > DRM_VMW_MAX_SURFACE_FACES * DRM_VMW_MAX_MIP_LEVELS)
return -EINVAL;

size = vmw_user_surface_size + 128 +
--
2.9.3

2017-03-25 03:30:57

by Sinclair Yeh

Subject: Re: [PATCH] drm/vmwgfx: Check check that number of mip levels is above zero in vmw_surface_define_ioctl()

Hi,

thank you for this patch. Murray McAllister reported this one a couple
of months ago, and this is already in our queue.

Sinclair

On Fri, Mar 24, 2017 at 04:37:10PM +0100, Vladis Dronov wrote:
> In vmw_surface_define_ioctl(), a num_sizes parameter is assigned a
> user-controlled value which is not checked for zero. It is used in
> a call to kmalloc() which returns ZERO_SIZE_PTR. Later ZERO_SIZE_PTR
> is dereferenced which leads to a GPF and possibly to a kernel panic.
> Add the check for zero to avoid this.
>
> Reference: https://urldefense.proofpoint.com/v2/url?u=https-3A__bugzilla.redhat.com_show-5Fbug.cgi-3Fid-3D1435719&d=DwIBAg&c=uilaK90D4TOVoH58JNXRgQ&r=HaJ2a6NYExoV0cntAYcoqA&m=OW9cIAAez9eRIxEYMaToDu2szuR_YrfQcOzAH6L8dXo&s=-3P2pG3n1YW6-8NG6mLC7kyxmx7mMxJmXgY79ZgQeo4&e=
> Signed-off-by: Vladis Dronov <[email protected]>
> ---
> drivers/gpu/drm/vmwgfx/vmwgfx_surface.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/gpu/drm/vmwgfx/vmwgfx_surface.c b/drivers/gpu/drm/vmwgfx/vmwgfx_surface.c
> index b445ce9..42840cc 100644
> --- a/drivers/gpu/drm/vmwgfx/vmwgfx_surface.c
> +++ b/drivers/gpu/drm/vmwgfx/vmwgfx_surface.c
> @@ -716,8 +716,8 @@ int vmw_surface_define_ioctl(struct drm_device *dev, void *data,
> for (i = 0; i < DRM_VMW_MAX_SURFACE_FACES; ++i)
> num_sizes += req->mip_levels[i];
>
> - if (num_sizes > DRM_VMW_MAX_SURFACE_FACES *
> - DRM_VMW_MAX_MIP_LEVELS)
> + if (num_sizes <= 0 ||
> + num_sizes > DRM_VMW_MAX_SURFACE_FACES * DRM_VMW_MAX_MIP_LEVELS)
> return -EINVAL;
>
> size = vmw_user_surface_size + 128 +
> --
> 2.9.3
>