systemd-importd runs qcow2_detect()/qcow2_convert() over images it has just
downloaded (see pull-raw.c), so the header, the L1/L2 tables and every offset
and cluster descriptor in them are attacker controlled. There is a manual test
for the happy path, but nothing that feeds it a malformed image.
The corpus is two images, a plain data cluster and a zlib-compressed one (i.e.
decompress_zlib_raw()), at the 512 byte minimum cluster size and trimmed to the
last byte the converter reads, so 2K each. A zero cluster and a QCOW3 header are
a flipped descriptor bit and a bumped version field away from these, so they are
left to the fuzzer rather than carried in the tree.
Armaan Sandhu
65c112007a