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=-18.9 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_GIT autolearn=unavailable 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 6C2CAC48BE6 for ; Wed, 16 Jun 2021 15:34:24 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 5552061166 for ; Wed, 16 Jun 2021 15:34:24 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234712AbhFPPg3 (ORCPT ); Wed, 16 Jun 2021 11:36:29 -0400 Received: from mail.kernel.org ([198.145.29.99]:49440 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234681AbhFPPg0 (ORCPT ); Wed, 16 Jun 2021 11:36:26 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id C9D7C6101B; Wed, 16 Jun 2021 15:34:19 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1623857660; bh=9YzhF267Tu8pj6vFG09DeCGbr7/bTkJnYyNa60yUF6U=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=1DJ3DwMvsFGIopsicAW+xBt4uM/lh9re04iKefKs3EcQvD7eUbkhKgir7RsmDy4Bt O8nbXrKDnx3j8ZIpLpzutOjgYSaYYpp/ivs2jVOe2RhAj8NfJLWnhcTV/eFmGWRSCq 65PBqtNZ9L1KDDoYpmnWcg+F70nUuuuo63TdzNmQ= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, syzbot , Hillf Danton , Andreas Gruenbacher , Sasha Levin Subject: [PATCH 5.4 14/28] gfs2: Fix use-after-free in gfs2_glock_shrink_scan Date: Wed, 16 Jun 2021 17:33:25 +0200 Message-Id: <20210616152834.607192012@linuxfoundation.org> X-Mailer: git-send-email 2.32.0 In-Reply-To: <20210616152834.149064097@linuxfoundation.org> References: <20210616152834.149064097@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Hillf Danton [ Upstream commit 1ab19c5de4c537ec0d9b21020395a5b5a6c059b2 ] The GLF_LRU flag is checked under lru_lock in gfs2_glock_remove_from_lru() to remove the glock from the lru list in __gfs2_glock_put(). On the shrink scan path, the same flag is cleared under lru_lock but because of cond_resched_lock(&lru_lock) in gfs2_dispose_glock_lru(), progress on the put side can be made without deleting the glock from the lru list. Keep GLF_LRU across the race window opened by cond_resched_lock(&lru_lock) to ensure correct behavior on both sides - clear GLF_LRU after list_del under lru_lock. Reported-by: syzbot Signed-off-by: Hillf Danton Signed-off-by: Andreas Gruenbacher Signed-off-by: Sasha Levin --- fs/gfs2/glock.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/fs/gfs2/glock.c b/fs/gfs2/glock.c index 9e1685a30bf8..01c41087f067 100644 --- a/fs/gfs2/glock.c +++ b/fs/gfs2/glock.c @@ -1552,6 +1552,7 @@ __acquires(&lru_lock) while(!list_empty(list)) { gl = list_entry(list->next, struct gfs2_glock, gl_lru); list_del_init(&gl->gl_lru); + clear_bit(GLF_LRU, &gl->gl_flags); if (!spin_trylock(&gl->gl_lockref.lock)) { add_back_to_lru: list_add(&gl->gl_lru, &lru_list); @@ -1597,7 +1598,6 @@ static long gfs2_scan_glock_lru(int nr) if (!test_bit(GLF_LOCK, &gl->gl_flags)) { list_move(&gl->gl_lru, &dispose); atomic_dec(&lru_count); - clear_bit(GLF_LRU, &gl->gl_flags); freed++; continue; } -- 2.30.2