hw/ppc/e500.c: Handle qemu_find_file() failure

If qemu_find_file() doesn't find the BIOS it returns NULL; we were
passing that unchecked through to load_elf(), which assumes a non-NULL
pointer and may misbehave. In practice it fails with a weird message:

  $ qemu-system-ppc -M ppce500 -display none -kernel nonesuch
  Bad address
  qemu-system-ppc: could not load firmware '(null)'

Handle the failure case better:

  $ qemu-system-ppc -M ppce500 -display none -kernel nonesuch
  qemu-system-ppc: could not find firmware/kernel file 'nonesuch'

Spotted by Coverity (CID 1238954).

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Message-Id: <20200324121216.23899-1-peter.maydell@linaro.org>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
1 file changed