Multiple buffer overflows in QEMU before 1.7.2 and 2.x before 2.0.0, allow local users to cause a denial of service (crash) or possibly execute arbitrary code via a large (1) L1 table in the qcow2_snapshot_load_tmp in the QCOW 2 block driver (block/qcow2-snapshot.c) or (2) uncompressed chunk, (3) chunk length, or (4) number of sectors in the DMG block driver (block/dmg.c).