Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754272AbdCFJm2 (ORCPT ); Mon, 6 Mar 2017 04:42:28 -0500 Received: from mx2.suse.de ([195.135.220.15]:37166 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753029AbdCFJMb (ORCPT ); Mon, 6 Mar 2017 04:12:31 -0500 X-Amavis-Alert: BAD HEADER SECTION, Duplicate header field: "References" From: Jiri Slaby To: stable@vger.kernel.org Cc: linux-kernel@vger.kernel.org, Francesco Ruggeri , Francesco Ruggeri , "David S . Miller" , Willy Tarreau , Jiri Slaby Subject: [PATCH 3.12 003/113] net: possible use after free in dst_release Date: Mon, 6 Mar 2017 10:10:27 +0100 Message-Id: X-Mailer: git-send-email 2.12.0 In-Reply-To: References: In-Reply-To: References: Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1439 Lines: 45 From: Francesco Ruggeri 3.12-stable review patch. If anyone has any objections, please let me know. =============== commit 07a5d38453599052aff0877b16bb9c1585f08609 upstream. 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 Cc: Willy Tarreau Signed-off-by: Jiri Slaby --- net/core/dst.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/net/core/dst.c b/net/core/dst.c index 31344009de25..08c9a8f7b885 100644 --- a/net/core/dst.c +++ b/net/core/dst.c @@ -280,12 +280,13 @@ void dst_release(struct dst_entry *dst) { if (dst) { int newrefcnt; + unsigned short nocache = dst->flags & DST_NOCACHE; newrefcnt = atomic_dec_return(&dst->__refcnt); if (unlikely(newrefcnt < 0)) net_warn_ratelimited("%s: dst:%p refcnt:%d\n", __func__, dst, newrefcnt); - if (!newrefcnt && unlikely(dst->flags & DST_NOCACHE)) + if (!newrefcnt && unlikely(nocache)) call_rcu(&dst->rcu_head, dst_destroy_rcu); } } -- 2.12.0