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drm: integer overflow in drm_mode_dirtyfb_ioctl()

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@gmail.com>
Signed-off-by: Xi Wang <xi.wang@gmail.com>
Cc: stable@kernel.org
Signed-off-by: Dave Airlie <airlied@redhat.com>
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xiw authored and airlied committed Nov 23, 2011
1 parent c916874 commit a5cd335165e31db9dbab636fd29895d41da55dd2
Showing with 6 additions and 0 deletions.
  1. +4 −0 drivers/gpu/drm/drm_crtc.c
  2. +2 −0 include/drm/drm_mode.h
@@ -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;
View
@@ -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.
*

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