From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-3.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 8F191C32751 for ; Sat, 10 Aug 2019 20:46:36 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 680C3208C3 for ; Sat, 10 Aug 2019 20:46:36 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727317AbfHJUq2 (ORCPT ); Sat, 10 Aug 2019 16:46:28 -0400 Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:55340 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726457AbfHJUoH (ORCPT ); Sat, 10 Aug 2019 16:44:07 -0400 Received: from [192.168.4.242] (helo=deadeye) by shadbolt.decadent.org.uk with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.89) (envelope-from ) id 1hwYDb-00053a-W5; Sat, 10 Aug 2019 21:44:04 +0100 Received: from ben by deadeye with local (Exim 4.92) (envelope-from ) id 1hwYDL-0003dJ-5n; Sat, 10 Aug 2019 21:43:47 +0100 Content-Type: text/plain; charset="UTF-8" Content-Disposition: inline Content-Transfer-Encoding: 8bit MIME-Version: 1.0 From: Ben Hutchings To: linux-kernel@vger.kernel.org, stable@vger.kernel.org CC: akpm@linux-foundation.org, Denis Kirjanov , "J. Bruce Fields" , "NeilBrown" Date: Sat, 10 Aug 2019 21:40:07 +0100 Message-ID: X-Mailer: LinuxStableQueue (scripts by bwh) X-Patchwork-Hint: ignore Subject: [PATCH 3.16 073/157] sunrpc: don't mark uninitialised items as VALID. In-Reply-To: X-SA-Exim-Connect-IP: 192.168.4.242 X-SA-Exim-Mail-From: ben@decadent.org.uk X-SA-Exim-Scanned: No (on shadbolt.decadent.org.uk); SAEximRunCond expanded to false Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.16.72-rc1 review patch. If anyone has any objections, please let me know. ------------------ From: NeilBrown commit d58431eacb226222430940134d97bfd72f292fcd upstream. A recent commit added a call to cache_fresh_locked() when an expired item was found. The call sets the CACHE_VALID flag, so it is important that the item actually is valid. There are two ways it could be valid: 1/ If ->update has been called to fill in relevant content 2/ if CACHE_NEGATIVE is set, to say that content doesn't exist. An expired item that is waiting for an update will be neither. Setting CACHE_VALID will mean that a subsequent call to cache_put() will be likely to dereference uninitialised pointers. So we must make sure the item is valid, and we already have code to do that in try_to_negate_entry(). This takes the hash lock and so cannot be used directly, so take out the two lines that we need and use them. Now cache_fresh_locked() is certain to be called only on a valid item. Fixes: 4ecd55ea0742 ("sunrpc: fix cache_head leak due to queued request") Signed-off-by: NeilBrown Signed-off-by: J. Bruce Fields [bwh: Backported to 3.16: adjust context] Signed-off-by: Ben Hutchings --- net/sunrpc/cache.c | 3 +++ 1 file changed, 3 insertions(+) --- a/net/sunrpc/cache.c +++ b/net/sunrpc/cache.c @@ -50,6 +50,7 @@ static void cache_init(struct cache_head h->last_refresh = now; } +static inline int cache_is_valid(struct cache_head *h); static void cache_fresh_locked(struct cache_head *head, time_t expiry); static void cache_fresh_unlocked(struct cache_head *head, struct cache_detail *detail); @@ -98,6 +99,8 @@ struct cache_head *sunrpc_cache_lookup(s *hp = tmp->next; tmp->next = NULL; detail->entries --; + if (cache_is_valid(tmp) == -EAGAIN) + set_bit(CACHE_NEGATIVE, &tmp->flags); cache_fresh_locked(tmp, 0); freeme = tmp; break;