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=-13.0 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_AGENT_GIT autolearn=ham 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 AB116C433E0 for ; Mon, 3 Aug 2020 12:29:00 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 880B02083B for ; Mon, 3 Aug 2020 12:29:00 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1596457740; bh=lhv4IwAgqn2rxgBpcw8dPa2pumagXqXev8znU1R0jLw=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=jYkChtaYjLHGE4icxhmJnFgb2F0HRXOhFHSadT4j0NSRQIjtaDYp6VNzFC9S0Ntxl VN+2xlXua9EJNzmVsgnN9iJ+b8ZmZklzMs9QC2W8NhxRTufpDdwzNa4ojc2dEzcw0h +dTndYtsHjghrNLlCSyKpLR6qOZPg9dz0fbMPZE0= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728840AbgHCM27 (ORCPT ); Mon, 3 Aug 2020 08:28:59 -0400 Received: from mail.kernel.org ([198.145.29.99]:55178 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728218AbgHCM2z (ORCPT ); Mon, 3 Aug 2020 08:28:55 -0400 Received: from localhost (83-86-89-107.cable.dynamic.v4.ziggo.nl [83.86.89.107]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 25B74204EC; Mon, 3 Aug 2020 12:28:53 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1596457733; bh=lhv4IwAgqn2rxgBpcw8dPa2pumagXqXev8znU1R0jLw=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=juaav0UmovZhGoVcbI94xhjk2sZUZstNR56UJKBYxYdEOiu0DnnSY7LTFDRyBHAim gim23RnauEkpk96CEW8o56MVMn2xoB8ntqv/9Ee52SVrr/FG7CdRRJQlpdt2uGOcFS PXBmNck3yswjd546xPfC+RNH136XmdRTvT77Uq5s= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, "Gong, Sishuai" , Herbert Xu , "David S. Miller" , Sasha Levin Subject: [PATCH 5.4 54/90] rhashtable: Fix unprotected RCU dereference in __rht_ptr Date: Mon, 3 Aug 2020 14:19:16 +0200 Message-Id: <20200803121900.241283758@linuxfoundation.org> X-Mailer: git-send-email 2.28.0 In-Reply-To: <20200803121857.546052424@linuxfoundation.org> References: <20200803121857.546052424@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Herbert Xu [ Upstream commit 1748f6a2cbc4694523f16da1c892b59861045b9d ] The rcu_dereference call in rht_ptr_rcu is completely bogus because we've already dereferenced the value in __rht_ptr and operated on it. This causes potential double readings which could be fatal. The RCU dereference must occur prior to the comparison in __rht_ptr. This patch changes the order of RCU dereference so that it is done first and the result is then fed to __rht_ptr. The RCU marking changes have been minimised using casts which will be removed in a follow-up patch. Fixes: ba6306e3f648 ("rhashtable: Remove RCU marking from...") Reported-by: "Gong, Sishuai" Signed-off-by: Herbert Xu Signed-off-by: David S. Miller Signed-off-by: Sasha Levin --- include/linux/rhashtable.h | 25 +++++++++++++------------ 1 file changed, 13 insertions(+), 12 deletions(-) diff --git a/include/linux/rhashtable.h b/include/linux/rhashtable.h index beb9a9da16994..c5bf21261bb19 100644 --- a/include/linux/rhashtable.h +++ b/include/linux/rhashtable.h @@ -349,11 +349,11 @@ static inline void rht_unlock(struct bucket_table *tbl, local_bh_enable(); } -static inline struct rhash_head __rcu *__rht_ptr( - struct rhash_lock_head *const *bkt) +static inline struct rhash_head *__rht_ptr( + struct rhash_lock_head *p, struct rhash_lock_head __rcu *const *bkt) { - return (struct rhash_head __rcu *) - ((unsigned long)*bkt & ~BIT(0) ?: + return (struct rhash_head *) + ((unsigned long)p & ~BIT(0) ?: (unsigned long)RHT_NULLS_MARKER(bkt)); } @@ -365,25 +365,26 @@ static inline struct rhash_head __rcu *__rht_ptr( * access is guaranteed, such as when destroying the table. */ static inline struct rhash_head *rht_ptr_rcu( - struct rhash_lock_head *const *bkt) + struct rhash_lock_head *const *p) { - struct rhash_head __rcu *p = __rht_ptr(bkt); - - return rcu_dereference(p); + struct rhash_lock_head __rcu *const *bkt = (void *)p; + return __rht_ptr(rcu_dereference(*bkt), bkt); } static inline struct rhash_head *rht_ptr( - struct rhash_lock_head *const *bkt, + struct rhash_lock_head *const *p, struct bucket_table *tbl, unsigned int hash) { - return rht_dereference_bucket(__rht_ptr(bkt), tbl, hash); + struct rhash_lock_head __rcu *const *bkt = (void *)p; + return __rht_ptr(rht_dereference_bucket(*bkt, tbl, hash), bkt); } static inline struct rhash_head *rht_ptr_exclusive( - struct rhash_lock_head *const *bkt) + struct rhash_lock_head *const *p) { - return rcu_dereference_protected(__rht_ptr(bkt), 1); + struct rhash_lock_head __rcu *const *bkt = (void *)p; + return __rht_ptr(rcu_dereference_protected(*bkt, 1), bkt); } static inline void rht_assign_locked(struct rhash_lock_head **bkt, -- 2.25.1