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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 9D90CC433FE for ; Fri, 4 Feb 2022 23:39:11 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1378286AbiBDXjK (ORCPT ); Fri, 4 Feb 2022 18:39:10 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:46266 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1378231AbiBDXjF (ORCPT ); Fri, 4 Feb 2022 18:39:05 -0500 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 1ED2BE025B2D; Fri, 4 Feb 2022 15:39:05 -0800 (PST) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id AA3A561C36; Fri, 4 Feb 2022 23:39:04 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 15A85C004E1; Fri, 4 Feb 2022 23:39:04 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1644017944; bh=4LJKR8LrRJnPaBrRYneeP2Xiv81UOQNEztaGmdaYkWg=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=CrzsfZAU6BrQKiS8paJXVOS+vA8vuIFNCndI6SQEWTMRK35sU2o4Iv1IOqMYp1DNE EHlAIlGcpJYO5oZO+4gv51pGE2AA5+jI/yqnS2urARjckX3XiMBzOCcRdC7oW384s3 /3T+UXNUGMnTD0ywBZ5ZN2BJxS6GoT79fkq7Fy/yrOHLverSXhREW/C3S2vNL9g2cZ 54OmKpSZitYdNPqseO9A8v8uqoG2qeZUvtqWtJJBW+9vn6Gq+7qN1n/EJug33iYA0C DH9xPy5u6D6LdVP8mnxiVmQli9LDIQOnpOcO5b6OBubqM4+swyPVj85VsJp/Vch1Ym mqe2robaYreAA== Received: by paulmck-ThinkPad-P17-Gen-1.home (Postfix, from userid 1000) id E77755C0418; Fri, 4 Feb 2022 15:39:03 -0800 (PST) From: "Paul E. McKenney" To: rcu@vger.kernel.org Cc: linux-kernel@vger.kernel.org, kernel-team@fb.com, rostedt@goodmis.org, "Paul E. McKenney" Subject: [PATCH rcu 01/19] srcu: Tighten cleanup_srcu_struct() GP checks Date: Fri, 4 Feb 2022 15:38:44 -0800 Message-Id: <20220204233902.1902-1-paulmck@kernel.org> X-Mailer: git-send-email 2.31.1.189.g2e36527f23 In-Reply-To: <20220204233858.GA1469@paulmck-ThinkPad-P17-Gen-1> References: <20220204233858.GA1469@paulmck-ThinkPad-P17-Gen-1> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Currently, cleanup_srcu_struct() checks for a grace period in progress, but it does not check for a grace period that has not yet started but which might start at any time. Such a situation could result in a use-after-free bug, so this commit adds a check for a grace period that is needed but not yet started to cleanup_srcu_struct(). Signed-off-by: Paul E. McKenney --- kernel/rcu/srcutree.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) diff --git a/kernel/rcu/srcutree.c b/kernel/rcu/srcutree.c index 6833d88871816..d30e4db04506a 100644 --- a/kernel/rcu/srcutree.c +++ b/kernel/rcu/srcutree.c @@ -382,9 +382,11 @@ void cleanup_srcu_struct(struct srcu_struct *ssp) return; /* Forgot srcu_barrier(), so just leak it! */ } if (WARN_ON(rcu_seq_state(READ_ONCE(ssp->srcu_gp_seq)) != SRCU_STATE_IDLE) || + WARN_ON(rcu_seq_current(&ssp->srcu_gp_seq) != ssp->srcu_gp_seq_needed) || WARN_ON(srcu_readers_active(ssp))) { - pr_info("%s: Active srcu_struct %p state: %d\n", - __func__, ssp, rcu_seq_state(READ_ONCE(ssp->srcu_gp_seq))); + pr_info("%s: Active srcu_struct %p read state: %d gp state: %lu/%lu\n", + __func__, ssp, rcu_seq_state(READ_ONCE(ssp->srcu_gp_seq)), + rcu_seq_current(&ssp->srcu_gp_seq), ssp->srcu_gp_seq_needed); return; /* Caller forgot to stop doing call_srcu()? */ } free_percpu(ssp->sda); -- 2.31.1.189.g2e36527f23