qcow1: Validate image size (CVE-2014-0223)

qcow1: Validate image size (CVE-2014-0223)

A huge image size could cause s->l1_size to overflow. Make sure that
images never require a L1 table larger than what fits in s->l1_size.

This cannot only cause unbounded allocations, but also the allocation of
a too small L1 table, resulting in out-of-bounds array accesses (both
reads and writes).

Cc: qemu-stable@nongnu.org
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
(cherry picked from commit 46485de0cb357b57373e1ca895adedf1f3ed46ec)
Signed-off-by: Michael Roth <mdroth@linux.vnet.ibm.com>