From: Xi Wang <xi.w...@gmail.com> ------------------- This is a commit scheduled for the next v2.6.34 longterm release. http://git.kernel.org/?p=linux/kernel/git/paulg/longterm-queue-2.6.34.git If you see a problem with using this for longterm, please comment. -------------------
commit a5cd335165e31db9dbab636fd29895d41da55dd2 upstream. 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 <haogangc...@gmail.com> Signed-off-by: Xi Wang <xi.w...@gmail.com> Signed-off-by: Dave Airlie <airl...@redhat.com> Signed-off-by: Paul Gortmaker <paul.gortma...@windriver.com> --- drivers/gpu/drm/drm_crtc.c | 4 ++++ include/drm/drm_mode.h | 2 ++ 2 files changed, 6 insertions(+) diff --git a/drivers/gpu/drm/drm_crtc.c b/drivers/gpu/drm/drm_crtc.c index 1a224f8..819d0dc 100644 --- a/drivers/gpu/drm/drm_crtc.c +++ b/drivers/gpu/drm/drm_crtc.c @@ -1833,6 +1833,10 @@ 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 c5ba163..9cf639c 100644 --- a/include/drm/drm_mode.h +++ b/include/drm/drm_mode.h @@ -232,6 +232,8 @@ 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. * -- 1.7.12.rc2 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/