tree 9b0d9883c85ff042a3a685a20f217debcfeaf089
parent e725dc164015d873b64639f0fee9ba5c30175f4c
author Greg Hackmann <ghackmann@google.com> 1458778502 -0700
committer Greg Hackmann <ghackmann@google.com> 1458862640 -0700

clone: check for NULL child stack

The clone syscall accepts NULL child stacks, interpreting this to mean
the child gets a copy of the parent's stack with copy-on-write
semantics.  However clone(2) is explicitly documented to treat this an
an error.

"Fortunately" every architecture's __bionic_clone implementation pushes
something onto the child stack before making the clone syscall.  So we
know fixing this won't break legacy apps, because any app that tried
using a NULL child stack would have died with SIGSEGV.

This change fixes the LTP clone04 testcase.

Change-Id: I663b34f34bc8dad2aa405c46e4eed4418cccca0d
Signed-off-by: Greg Hackmann <ghackmann@google.com>