tree dd0b4d81580b177d2d4a5371a75ae8fdf3afe5bc
parent 2dbfadf60654ea5eecd5df77babaa92831954a98
author Alberto Garcia <berto@igalia.com> 1549640693 +0200
committer Kevin Wolf <kwolf@redhat.com> 1551103523 +0100

qcow2: Assert that L2 table offsets fit in the L1 table

L1 table entries have a field to store the offset of an L2 table.
The rest of the bits of the entry are currently reserved except from
bit 63, which stores the COPIED flag.

The offset is always taken from the entry using L1E_OFFSET_MASK to
ensure that we only use the bits that belong to that field.

While that mask is used every time we read from the L1 table, it is
never used when we write to it. Due to the limits set elsewhere in the
code QEMU can never produce L2 table offsets that don't fit in that
field so any such offset when allocating an L2 table would indicate a
bug in QEMU.

Signed-off-by: Alberto Garcia <berto@igalia.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>