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Date: Sat, 14 Dec 2013 17:33:17 +0100 From: Oleg Nesterov <oleg@...hat.com> To: Paul Moore <paul@...l-moore.com> Cc: Stephen Smalley <sds@...ho.nsa.gov>, James Morris <james.l.morris@...cle.com>, Eric Paris <eparis@...isplace.org>, Evan McNabb <emcnabb@...hat.com>, Jan Stancek <jstancek@...hat.com>, linux-kernel@...r.kernel.org Subject: [PATCH v2] 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@...hat.com> Signed-off-by: Oleg Nesterov <oleg@...hat.com> --- security/selinux/hooks.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) --- a/security/selinux/hooks.c +++ b/security/selinux/hooks.c @@ -5503,11 +5503,11 @@ static int selinux_setprocattr(struct ta /* 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, -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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