Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753951AbbLIJip (ORCPT ); Wed, 9 Dec 2015 04:38:45 -0500 Received: from youngberry.canonical.com ([91.189.89.112]:44985 "EHLO youngberry.canonical.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753878AbbLIJin (ORCPT ); Wed, 9 Dec 2015 04:38:43 -0500 From: Luis Henriques To: linux-kernel@vger.kernel.org, stable@vger.kernel.org, kernel-team@lists.ubuntu.com Cc: Eric Dumazet , "David S. Miller" , Luis Henriques Subject: [PATCH 3.16.y-ckt 012/126] net: fix a race in dst_release() Date: Wed, 9 Dec 2015 09:36:22 +0000 Message-Id: <1449653896-5236-13-git-send-email-luis.henriques@canonical.com> In-Reply-To: <1449653896-5236-1-git-send-email-luis.henriques@canonical.com> References: <1449653896-5236-1-git-send-email-luis.henriques@canonical.com> X-Extended-Stable: 3.16 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1408 Lines: 41 3.16.7-ckt21 -stable review patch. If anyone has any objections, please let me know. ------------------ From: Eric Dumazet commit d69bbf88c8d0b367cf3e3a052f6daadf630ee566 upstream. Only cpu seeing dst refcount going to 0 can safely dereference dst->flags. Otherwise an other cpu might already have freed the dst. Fixes: 27b75c95f10d ("net: avoid RCU for NOCACHE dst") Reported-by: Greg Thelen Signed-off-by: Eric Dumazet Signed-off-by: David S. Miller [ luis: backported to 3.16: adjusted context ] Signed-off-by: Luis Henriques --- net/core/dst.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/net/core/dst.c b/net/core/dst.c index a028409ee438..a80e92346b9b 100644 --- a/net/core/dst.c +++ b/net/core/dst.c @@ -285,7 +285,7 @@ void dst_release(struct dst_entry *dst) newrefcnt = atomic_dec_return(&dst->__refcnt); WARN_ON(newrefcnt < 0); - if (unlikely(dst->flags & DST_NOCACHE) && !newrefcnt) + if (!newrefcnt && unlikely(dst->flags & DST_NOCACHE)) call_rcu(&dst->rcu_head, dst_destroy_rcu); } } -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/