On Fri, May 24, 2024 at 02:38:04PM +0200, Jiri Bohac wrote:
> On Fri, May 24, 2024 at 12:15:47PM +0200, Greg Kroah-Hartman wrote:
> > Nice, but then why was this commit worded this way? Now we check twice?
> > Double safe? Should it be reverted?
>
> double safe's good; turning it into a CVE not so much :(
> CVE-2023-52822, CVE-2023-52824 and CVE-2023-52820, originally from the same patch
> series, seem to be the exact same case.
>
> CVE-2023-52822:
>
> int vmw_surface_define_ioctl(struct drm_device *dev, void *data,
> struct drm_file *file_priv)
> {
> ...
> if (num_sizes > DRM_VMW_MAX_SURFACE_FACES * DRM_VMW_MAX_MIP_LEVELS ||
> num_sizes == 0)
> return -EINVAL;
> ...
> metadata->num_sizes = num_sizes;
> metadata->sizes =
> memdup_user((struct drm_vmw_size __user *)(unsigned long)
> req->size_addr,
> sizeof(*metadata->sizes) * metadata->num_sizes);
> }
Agreed, now rejected.
> CVE-2023-52824 (here the check is in the immediately preceeding statement, could it
> be any more obvious?):
>
> long watch_queue_set_filter(struct pipe_inode_info *pipe,
> struct watch_notification_filter __user *_filter)
> {
> if (filter.nr_filters == 0 ||
> filter.nr_filters > 16 ||
> filter.__reserved != 0)
> return -EINVAL;
>
> tf = memdup_user(_filter->filters, filter.nr_filters * sizeof(*tf));
> }
Yup, now rejected.
>
>
> CVE-2023-52820 is a little less obvious to be safe, but I believe it is:
>
> int drm_mode_create_lease_ioctl(struct drm_device *dev,
> void *data, struct drm_file *lessor_priv)
> {
> ...
> object_ids = memdup_user(u64_to_user_ptr(cl->object_ids),
> array_size(object_count, sizeof(__u32)));
>
> array_size() will safely multiply object_count * 4 and return SIZE_MAX on
> overflow, making the kmalloc inside memdup_user cleanly fail with -ENOMEM.
Also agreed, now rejected.
thanks,
greg k-h
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