From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail.linuxfoundation.org ([140.211.169.12]:59932 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S967310AbcA0Ttr (ORCPT ); Wed, 27 Jan 2016 14:49:47 -0500 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Francesco Ruggeri , Eric Dumazet , "David S. Miller" Subject: [PATCH 3.10 37/53] net: possible use after free in dst_release Date: Wed, 27 Jan 2016 10:15:56 -0800 Message-Id: <20160127180650.845248272@linuxfoundation.org> In-Reply-To: <20160127180648.932559859@linuxfoundation.org> References: <20160127180648.932559859@linuxfoundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-15 Sender: stable-owner@vger.kernel.org List-ID: 3.10-stable review patch. If anyone has any objections, please let me know. ------------------ From: Francesco Ruggeri [ Upstream commit 07a5d38453599052aff0877b16bb9c1585f08609 ] dst_release should not access dst->flags after decrementing __refcnt to 0. The dst_entry may be in dst_busy_list and dst_gc_task may dst_destroy it before dst_release gets a chance to access dst->flags. Fixes: d69bbf88c8d0 ("net: fix a race in dst_release()") Fixes: 27b75c95f10d ("net: avoid RCU for NOCACHE dst") Signed-off-by: Francesco Ruggeri Acked-by: Eric Dumazet Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman --- net/core/dst.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) --- a/net/core/dst.c +++ b/net/core/dst.c @@ -280,10 +280,11 @@ void dst_release(struct dst_entry *dst) { if (dst) { int newrefcnt; + unsigned short nocache = dst->flags & DST_NOCACHE; newrefcnt = atomic_dec_return(&dst->__refcnt); WARN_ON(newrefcnt < 0); - if (!newrefcnt && unlikely(dst->flags & DST_NOCACHE)) + if (!newrefcnt && unlikely(nocache)) call_rcu(&dst->rcu_head, dst_destroy_rcu); } }