On 2026/07/30 1:14, [email protected] wrote:
From: Marc-André Lureau <[email protected]>virtio_gpu_resource_create_blob() stores the guest-controlled blob_size without checking it against the total size of the iov backing entries. Since both values are independently guest-controlled, a malicious guest can set blob_size much larger than the actual iov backing. Subsequent SET_SCANOUT_BLOB checks bounds against the inflated blob_size, allowing a pixman surface to be created over the undersized buffer. Any display refresh then reads past the actual allocation, potentially crashing QEMU or leaking host memory contents depending on the backing type. Validate that the iov backing is at least as large as the declared blob_size in create_blob (when nr_entries > 0, since the spec permits deferred backing), attach_backing (when attaching to a blob resource), and the blob migration load path. Fixes: CVE-2026-66021 Fixes: e0933d91b1cd ("virtio-gpu: Add virtio_gpu_resource_create_blob") Resolves: https://gitlab.com/qemu-project/qemu/-/work_items/3945 Reported-by: "sundayjiang(蒋浩天)" <[email protected]> Signed-off-by: Marc-André Lureau <[email protected]>
Reviewed-by: Akihiko Odaki <[email protected]> Regards, Akihiko Odaki
