Richard Jones caught this bug with afl fuzzer.
In fact, that's the only possible value to overflow (extent->l1_size =
0x20000000) l1_size:
l1_size = extent->l1_size * sizeof(long) => 0x80000000;
g_try_malloc returns NULL because l1_size is interpreted as negative
during type casting from 'int' to 'gsize', which yields a enormous
value. Hence, by coincidence, we get a "not too bad" behavior:
qemu-img: Could not open '/tmp/afl6.img': Could not open
'/tmp/afl6.img': Cannot allocate memory
Values larger than 0x20000000 will be refused by the validation in
vmdk_add_extent.
Values smaller than 0x20000000 will not overflow l1_size.
Cc: qemu-stable@nongnu.org
Reported-by: Richard W.M. Jones <rjones@redhat.com>
Signed-off-by: Fam Zheng <famz@redhat.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Tested-by: Richard W.M. Jones <rjones@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
13c4941cdd