Commit c0c14395 authored by Oleg Nesterov's avatar Oleg Nesterov Committed by Paul Moore

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: default avatarEvan McNabb <emcnabb@redhat.com>
Signed-off-by: default avatarOleg Nesterov <oleg@redhat.com>
Cc: stable@vger.kernel.org
Signed-off-by: default avatarPaul Moore <pmoore@redhat.com>
parent 46d01d63
......@@ -5588,11 +5588,11 @@ 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,
......
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