tree e430e1d9e869d9e08a0a7e8677951465568d17dc
parent 46d01d63221c3508421dd72ff9c879f61053cffc
author Oleg Nesterov <oleg@redhat.com> 1387838701 -0500
committer Paul Moore <pmoore@redhat.com> 1387838717 -0500

selinux: selinux_setprocattr()->ptrace_parent() needs rcu_read_lock()

selinux_setprocattr() does ptrace_parent(p) under task_lock(p),
but task_struct->alloc_lock doesn't pin ->parent or ->ptrace,
this looks confusing and triggers the "suspicious RCU usage"
warning because ptrace_parent() does rcu_dereference_check().

And in theory this is wrong, spin_lock()->preempt_disable()
doesn't necessarily imply rcu_read_lock() we need to access
the ->parent.

Reported-by: Evan McNabb <emcnabb@redhat.com>
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Cc: stable@vger.kernel.org
Signed-off-by: Paul Moore <pmoore@redhat.com>