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=-10.5 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY, 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 CEA81C43387 for ; Fri, 11 Jan 2019 14:41:16 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 9F551206B6 for ; Fri, 11 Jan 2019 14:41:16 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1547217676; bh=9EH/BuI1qT7BNmO0SFPLIzOeYvhtQel8qalD2WkM9Ew=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=iJ8yaqoSoBftYECA2ZFHXlsxJ07GOc1fB9SBif4CiX1LDTTarcCtshII6ZoxSWN00 lqUr8iPxUSz/mrVEd9yHrUATOQA8FhnOZ9IH7pmuuFV+BgXAYREp7M+ClNH4HGZDAA J1R7h0LruUeMHCNxuUTFTLbOplT0B0UCJyO0mW4A= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2387577AbfAKOlQ (ORCPT ); Fri, 11 Jan 2019 09:41:16 -0500 Received: from mail.kernel.org ([198.145.29.99]:33868 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2403979AbfAKOlL (ORCPT ); Fri, 11 Jan 2019 09:41:11 -0500 Received: from localhost (5356596B.cm-6-7b.dynamic.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 51CC32063F; Fri, 11 Jan 2019 14:41:10 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1547217670; bh=9EH/BuI1qT7BNmO0SFPLIzOeYvhtQel8qalD2WkM9Ew=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=i7y4zbxzJB5Xu6DyKGSN9m5GKmODulGCPN9Kbm0oGgDBHRBBo4h+fDp8xJTN7oMmP t5vhG7zjUe7bKENFZp9KwpGb2nCJuU/6Dh4XfHKB/7ITx8TtOru4RbC1EYZ54NAn4o rAdXmzI5MsamN8O36N/Zyueer+XbdqNuGYF0OH3o= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Bart Van Assche , Christoph Hellwig , Sebastian Kuzminsky , Dennis Krein , "Paul E. McKenney" Subject: [PATCH 4.19 109/148] srcu: Lock srcu_data structure in srcu_gp_start() Date: Fri, 11 Jan 2019 15:14:47 +0100 Message-Id: <20190111131118.571242496@linuxfoundation.org> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20190111131114.337122649@linuxfoundation.org> References: <20190111131114.337122649@linuxfoundation.org> User-Agent: quilt/0.65 X-stable: review X-Patchwork-Hint: ignore 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 4.19-stable review patch. If anyone has any objections, please let me know. ------------------ From: Dennis Krein commit eb4c2382272ae7ae5d81fdfa5b7a6c86146eaaa4 upstream. The srcu_gp_start() function is called with the srcu_struct structure's ->lock held, but not with the srcu_data structure's ->lock. This is problematic because this function accesses and updates the srcu_data structure's ->srcu_cblist, which is protected by that lock. Failing to hold this lock can result in corruption of the SRCU callback lists, which in turn can result in arbitrarily bad results. This commit therefore makes srcu_gp_start() acquire the srcu_data structure's ->lock across the calls to rcu_segcblist_advance() and rcu_segcblist_accelerate(), thus preventing this corruption. Reported-by: Bart Van Assche Reported-by: Christoph Hellwig Reported-by: Sebastian Kuzminsky Signed-off-by: Dennis Krein Signed-off-by: Paul E. McKenney Tested-by: Dennis Krein Cc: # 4.16.x Signed-off-by: Greg Kroah-Hartman --- kernel/rcu/srcutree.c | 2 ++ 1 file changed, 2 insertions(+) --- a/kernel/rcu/srcutree.c +++ b/kernel/rcu/srcutree.c @@ -448,10 +448,12 @@ static void srcu_gp_start(struct srcu_st lockdep_assert_held(&ACCESS_PRIVATE(sp, lock)); WARN_ON_ONCE(ULONG_CMP_GE(sp->srcu_gp_seq, sp->srcu_gp_seq_needed)); + spin_lock_rcu_node(sdp); /* Interrupts already disabled. */ rcu_segcblist_advance(&sdp->srcu_cblist, rcu_seq_current(&sp->srcu_gp_seq)); (void)rcu_segcblist_accelerate(&sdp->srcu_cblist, rcu_seq_snap(&sp->srcu_gp_seq)); + spin_unlock_rcu_node(sdp); /* Interrupts remain disabled. */ smp_mb(); /* Order prior store to ->srcu_gp_seq_needed vs. GP start. */ rcu_seq_start(&sp->srcu_gp_seq); state = rcu_seq_state(READ_ONCE(sp->srcu_gp_seq));