Cc'ed Dave's work email.
On Wed, Nov 23, 2011 at 2:12 PM, Xi Wang <xi.wang at gmail.com> wrote:
> There is a potential integer overflow in drm_mode_dirtyfb_ioctl()
> if userspace passes in a large num_clips. ?The call to kmalloc would
> allocate a small buffer, and the call to fb->funcs->dirty may result
> in a memory corruption.
>
> Reported-by: Haogang Chen <haogangchen at gmail.com>
> Signed-off-by: Xi Wang <xi.wang at gmail.com>
> ---
> ?drivers/gpu/drm/drm_crtc.c | ? ?4 ++++
> ?include/drm/drm_mode.h ? ? | ? ?2 ++
> ?2 files changed, 6 insertions(+), 0 deletions(-)
>
> diff --git a/drivers/gpu/drm/drm_crtc.c b/drivers/gpu/drm/drm_crtc.c
> index 405c63b..8323fc3 100644
> --- a/drivers/gpu/drm/drm_crtc.c
> +++ b/drivers/gpu/drm/drm_crtc.c
> @@ -1873,6 +1873,10 @@ int drm_mode_dirtyfb_ioctl(struct drm_device *dev,
> ? ? ? ?}
>
> ? ? ? ?if (num_clips && clips_ptr) {
> + ? ? ? ? ? ? ? if (num_clips < 0 || num_clips > DRM_MODE_FB_DIRTY_MAX_CLIPS)
> {
> + ? ? ? ? ? ? ? ? ? ? ? ret = -EINVAL;
> + ? ? ? ? ? ? ? ? ? ? ? goto out_err1;
> + ? ? ? ? ? ? ? }
> ? ? ? ? ? ? ? ?clips = kzalloc(num_clips * sizeof(*clips), GFP_KERNEL);
> ? ? ? ? ? ? ? ?if (!clips) {
> ? ? ? ? ? ? ? ? ? ? ? ?ret = -ENOMEM;
> diff --git a/include/drm/drm_mode.h b/include/drm/drm_mode.h
> index d30bedf..ddd46db 100644
> --- a/include/drm/drm_mode.h
> +++ b/include/drm/drm_mode.h
> @@ -235,6 +235,8 @@ struct drm_mode_fb_cmd {
> ?#define DRM_MODE_FB_DIRTY_ANNOTATE_FILL 0x02
> ?#define DRM_MODE_FB_DIRTY_FLAGS ? ? ? ? 0x03
>
> +#define DRM_MODE_FB_DIRTY_MAX_CLIPS ? ? 256
> +
> ?/*
> ?* Mark a region of a framebuffer as dirty.
> ?*
> --
> 1.7.5.4
>
