| From | Kamal Mostafa <> | Subject | [PATCH 3.8 110/166] selinux: selinux_setprocattr()->ptrace_parent() needs rcu_read_lock() | Date | Wed, 15 Jan 2014 13:52:04 -0800 |
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3.8.13.16 -stable review patch. If anyone has any objections, please let me know.
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From: Oleg Nesterov <oleg@redhat.com>
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: Kamal Mostafa <kamal@canonical.com> --- security/selinux/hooks.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c index 0963169..6b0b250 100644 --- a/security/selinux/hooks.c +++ b/security/selinux/hooks.c @@ -5455,11 +5455,11 @@ static int selinux_setprocattr(struct task_struct *p, /* Check for ptracing, and update the task SID if ok. Otherwise, leave SID unchanged and fail. */ ptsid = 0; - task_lock(p); + rcu_read_lock(); tracer = ptrace_parent(p); if (tracer) ptsid = task_sid(tracer); - task_unlock(p); + rcu_read_unlock(); if (tracer) { error = avc_has_perm(ptsid, sid, SECCLASS_PROCESS, -- 1.8.3.2
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