binfmt_elf: Use elf_load() for interpreter

binfmt_elf: Use elf_load() for interpreter

Handle arbitrary memsz>filesz in interpreter ELF segments, instead of
only supporting it in the last segment (which is expected to be the
BSS).

Cc: Eric Biederman <ebiederm@xmission.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Christian Brauner <brauner@kernel.org>
Cc: linux-fsdevel@vger.kernel.org
Cc: linux-mm@kvack.org
Reported-by: Pedro Falcato <pedro.falcato@gmail.com>
Closes: https://lore.kernel.org/lkml/20221106021657.1145519-1-pedro.falcato@gmail.com/
Tested-by: Pedro Falcato <pedro.falcato@gmail.com>
Signed-off-by: Sebastian Ott <sebott@redhat.com>
Link: https://lore.kernel.org/r/20230929032435.2391507-3-keescook@chromium.org
Signed-off-by: Kees Cook <keescook@chromium.org>