Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933265AbcJLNBT (ORCPT ); Wed, 12 Oct 2016 09:01:19 -0400 Received: from mail.kernel.org ([198.145.29.136]:47610 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932622AbcJLMo3 (ORCPT ); Wed, 12 Oct 2016 08:44:29 -0400 From: lizf@kernel.org To: stable@vger.kernel.org Cc: linux-kernel@vger.kernel.org, Francesco Ruggeri , Francesco Ruggeri , "David S. Miller" , Zefan Li Subject: [PATCH 3.4 110/125] net: possible use after free in dst_release Date: Wed, 12 Oct 2016 20:33:46 +0800 Message-Id: <1476275641-4697-110-git-send-email-lizf@kernel.org> X-Mailer: git-send-email 1.9.1 In-Reply-To: <1476275600-4626-1-git-send-email-lizf@kernel.org> References: <1476275600-4626-1-git-send-email-lizf@kernel.org> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1366 Lines: 44 From: Francesco Ruggeri 3.4.113-rc1 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 [lizf: Backported to 3.4: adjust context] Signed-off-by: Zefan Li --- 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 54ba1eb..48cff89 100644 --- a/net/core/dst.c +++ b/net/core/dst.c @@ -269,10 +269,11 @@ 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)) { dst = dst_destroy(dst); if (dst) __dst_free(dst); -- 1.9.1