From: Oleg Nesterov <oleg@redhat.com>
Date: Mon, 23 Dec 2013 22:45:01 +0000 (-0500)
Subject: selinux: selinux_setprocattr()->ptrace_parent() needs rcu_read_lock()
X-Git-Tag: v3.2.55~21
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=5826e620694c056e27dae2f1e1e31005c93ab7e0;p=pandora-kernel.git

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

commit c0c1439541f5305b57a83d599af32b74182933fe upstream.

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>
Signed-off-by: Paul Moore <pmoore@redhat.com>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
---

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