linux-kernel - [092/102] AppArmor: Fix reference to rcu protected pointer outside of rcu_read

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Message-Id: <20110803221253.336284856@clark.kroah.org>
Date:	Wed, 03 Aug 2011 15:01:52 -0700
From:	Greg KH <gregkh@...e.de>
To:	linux-kernel@...r.kernel.org, stable@...nel.org
Cc:	stable-review@...nel.org, torvalds@...ux-foundation.org,
	akpm@...ux-foundation.org, alan@...rguk.ukuu.org.uk,
	John Johansen <john.johansen@...onical.com>
Subject: [092/102] AppArmor: Fix reference to rcu protected pointer outside of rcu_read_lock

3.0-stable review patch.  If anyone has any objections, please let us know.

------------------

From: John Johansen <john.johansen@...onical.com>

commit 04fdc099f9c80c7775dbac388fc97e156d4d47e7 upstream.

The pointer returned from tracehook_tracer_task() is only valid inside
the rcu_read_lock.  However the tracer pointer obtained is being passed
to aa_may_ptrace outside of the rcu_read_lock critical section.

Mover the aa_may_ptrace test into the rcu_read_lock critical section, to
fix this.

Kernels affected: 2.6.36 - 3.0

Reported-by: Oleg Nesterov <oleg@...hat.com>
Signed-off-by: John Johansen <john.johansen@...onical.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...e.de>

---
 security/apparmor/domain.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/security/apparmor/domain.c
+++ b/security/apparmor/domain.c
@@ -73,7 +73,6 @@ static int may_change_ptraced_domain(str
 		cred = get_task_cred(tracer);
 		tracerp = aa_cred_profile(cred);
 	}
-	rcu_read_unlock();
 
 	/* not ptraced */
 	if (!tracer || unconfined(tracerp))
@@ -82,6 +81,7 @@ static int may_change_ptraced_domain(str
 	error = aa_may_ptrace(tracer, tracerp, to_profile, PTRACE_MODE_ATTACH);
 
 out:
+	rcu_read_unlock();
 	if (cred)
 		put_cred(cred);
 


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