vg_prepare_blob() assumes a valid return from fdt_num_mem_rsv() in order
to make sensible initialization of the valgrind mem checker. Usually
that's fine, but it breaks down on the (deliberately corrupted)
truncated_memrsv testcase.
That led to marking a negative-size (== enormously sized once cast to
size_t) as defined with VALGRIND_MAKE_MEM_DEFINED, which casued valgrind
to freeze up and consume ludicrous amounts of memory until OOMing.
This correction makes us robust in that case.
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
David Gibson