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=-19.4 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,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 8304BC2B9F4 for ; Mon, 28 Jun 2021 15:24:57 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 672AD61457 for ; Mon, 28 Jun 2021 15:24:57 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235652AbhF1P1T (ORCPT ); Mon, 28 Jun 2021 11:27:19 -0400 Received: from mail.kernel.org ([198.145.29.99]:38868 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S236769AbhF1PCi (ORCPT ); Mon, 28 Jun 2021 11:02:38 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 30E3B61CD3; Mon, 28 Jun 2021 14:43:03 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1624891383; bh=F5O9Api5/iELcugHSMjGXBouRRs5jTzjdVT1RMVHu9w=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=YFjevwwfm3dXphmPVLTwslnS8e1K1jF++i9AJS0BSsNGkSNgl3Q0As+epJxyOLDLy WjYxdFsHVtIiOqcjyMl28hEqKS2t7Bo4rY3ipeoGgzIhTssqR1tKGxULlY0o/0YJ0A /quiEbeexu6QsL0CvNDx71ysB+Sth80DtC/SVJcwC+fLDXnsiyqLOjjP50fRHLD7er RfSQRTPjG8CrhCYLwtT4NChBG2y5KbCQQc5oVSFXQe0S1hfQIk/5JgKa6PgI/qSp25 M8Oig6IBatKLQsEs89+nrFPi1acVUUfCoM3uYxj89LcsEuleNvLCuLIwd6Ck1fOxzT cJkg3xWeKrxRw== From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Hillf Danton , syzbot , Andreas Gruenbacher , Sasha Levin Subject: [PATCH 4.4 06/57] gfs2: Fix use-after-free in gfs2_glock_shrink_scan Date: Mon, 28 Jun 2021 10:42:05 -0400 Message-Id: <20210628144256.34524-7-sashal@kernel.org> X-Mailer: git-send-email 2.30.2 In-Reply-To: <20210628144256.34524-1-sashal@kernel.org> References: <20210628144256.34524-1-sashal@kernel.org> MIME-Version: 1.0 X-KernelTest-Patch: http://kernel.org/pub/linux/kernel/v4.x/stable-review/patch-4.4.274-rc1.gz X-KernelTest-Tree: git://git.kernel.org/pub/scm/linux/kernel/git/stable/linux-stable-rc.git X-KernelTest-Branch: linux-4.4.y X-KernelTest-Patches: git://git.kernel.org/pub/scm/linux/kernel/git/stable/stable-queue.git X-KernelTest-Version: 4.4.274-rc1 X-KernelTest-Deadline: 2021-06-30T14:42+00:00 X-stable: review X-Patchwork-Hint: Ignore 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 8e8695eb652a..f115ce93dfb4 100644 --- a/fs/gfs2/glock.c +++ b/fs/gfs2/glock.c @@ -1342,6 +1342,7 @@ __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); @@ -1388,7 +1389,6 @@ 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