From bab9efc206ba89766c53a9042eb771e87e68c42b Mon Sep 17 00:00:00 2001 From: Xi Wang Date: Mon, 28 Nov 2011 12:25:43 +0100 Subject: [PATCH] vmwgfx: integer overflow in vmw_kms_update_layout_ioctl() There are two issues in vmw_kms_update_layout_ioctl(). First, the for loop forgets to index rects and only checks the first element. Second, there is a potential integer overflow if userspace passes in a large arg->num_outputs. The call to kzalloc() would allocate a small buffer, leading to out-of-bounds read. Reported-by: Haogang Chen Signed-off-by: Xi Wang Signed-off-by: Thomas Hellstrom Signed-off-by: Dave Airlie --- drivers/gpu/drm/vmwgfx/vmwgfx_kms.c | 11 ++++++----- 1 file changed, 6 insertions(+), 5 deletions(-) diff --git a/drivers/gpu/drm/vmwgfx/vmwgfx_kms.c b/drivers/gpu/drm/vmwgfx/vmwgfx_kms.c index 880e285d757..37d40545ed7 100644 --- a/drivers/gpu/drm/vmwgfx/vmwgfx_kms.c +++ b/drivers/gpu/drm/vmwgfx/vmwgfx_kms.c @@ -1809,7 +1809,8 @@ int vmw_kms_update_layout_ioctl(struct drm_device *dev, void *data, } rects_size = arg->num_outputs * sizeof(struct drm_vmw_rect); - rects = kzalloc(rects_size, GFP_KERNEL); + rects = kcalloc(arg->num_outputs, sizeof(struct drm_vmw_rect), + GFP_KERNEL); if (unlikely(!rects)) { ret = -ENOMEM; goto out_unlock; @@ -1824,10 +1825,10 @@ int vmw_kms_update_layout_ioctl(struct drm_device *dev, void *data, } for (i = 0; i < arg->num_outputs; ++i) { - if (rects->x < 0 || - rects->y < 0 || - rects->x + rects->w > mode_config->max_width || - rects->y + rects->h > mode_config->max_height) { + if (rects[i].x < 0 || + rects[i].y < 0 || + rects[i].x + rects[i].w > mode_config->max_width || + rects[i].y + rects[i].h > mode_config->max_height) { DRM_ERROR("Invalid GUI layout.\n"); ret = -EINVAL; goto out_free; -- 2.11.4.GIT