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 EF0C2C4332F for ; Sun, 12 Nov 2023 13:29:58 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232173AbjKLNaA (ORCPT ); Sun, 12 Nov 2023 08:30:00 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:48028 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231947AbjKLN2h (ORCPT ); Sun, 12 Nov 2023 08:28:37 -0500 Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 3217846AD; Sun, 12 Nov 2023 05:28:21 -0800 (PST) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 06B47C433C7; Sun, 12 Nov 2023 13:28:19 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1699795700; bh=dZuCJf/iMFEK2sPOo78BtdaRWKJF7aMxRStf0BNOTdQ=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=ieX4OT0kXaoAQ9iglJ/ucjqibK52IwNd3QuINfDirvc31i6blqOUITPCTPIKbh/PU HkzeOM4HJjcp1KQ++oscrXPXg+nvMJDt7a1RGRehXE/3//IC/YrNDYpf4uE68qrb5m j2GrwXXEtuZ09JSYRviwx+6gzPMViQIh3VB8RrpKaRyh1GtmTImjbErzj7GRZQL+gZ ClxUy3qxOupiKz4TPwSsYHoTt9N6I1jQBwBCfgUzFsgTOnQtG6C5KQLoQeCsRWa+P4 YlF72OvX3ocVsU5T5rcuJlv7iV1LycoZj8TrNKg7NTu8VsJf5RQRlKs/o5YEndxzGu Q9Oo4Xh7hZ0MA== From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Al Viro , Andreas Gruenbacher , Sasha Levin , swhiteho@redhat.com, rpeterso@redhat.com, cluster-devel@redhat.com Subject: [PATCH AUTOSEL 6.1 4/9] gfs2: fix an oops in gfs2_permission Date: Sun, 12 Nov 2023 08:28:07 -0500 Message-ID: <20231112132814.176005-4-sashal@kernel.org> X-Mailer: git-send-email 2.42.0 In-Reply-To: <20231112132814.176005-1-sashal@kernel.org> References: <20231112132814.176005-1-sashal@kernel.org> MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore X-stable-base: Linux 6.1.62 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Al Viro [ Upstream commit 0abd1557e21c617bd13fc18f7725fc6363c05913 ] In RCU mode, we might race with gfs2_evict_inode(), which zeroes ->i_gl. Freeing of the object it points to is RCU-delayed, so if we manage to fetch the pointer before it's been replaced with NULL, we are fine. Check if we'd fetched NULL and treat that as "bail out and tell the caller to get out of RCU mode". Signed-off-by: Al Viro Signed-off-by: Andreas Gruenbacher Signed-off-by: Sasha Levin --- fs/gfs2/inode.c | 11 +++++++++-- fs/gfs2/super.c | 2 +- 2 files changed, 10 insertions(+), 3 deletions(-) diff --git a/fs/gfs2/inode.c b/fs/gfs2/inode.c index 04a201584fa7c..d126b02893eb0 100644 --- a/fs/gfs2/inode.c +++ b/fs/gfs2/inode.c @@ -1847,14 +1847,21 @@ int gfs2_permission(struct user_namespace *mnt_userns, struct inode *inode, { struct gfs2_inode *ip; struct gfs2_holder i_gh; + struct gfs2_glock *gl; int error; gfs2_holder_mark_uninitialized(&i_gh); ip = GFS2_I(inode); - if (gfs2_glock_is_locked_by_me(ip->i_gl) == NULL) { + gl = rcu_dereference(ip->i_gl); + if (unlikely(!gl)) { + /* inode is getting torn down, must be RCU mode */ + WARN_ON_ONCE(!(mask & MAY_NOT_BLOCK)); + return -ECHILD; + } + if (gfs2_glock_is_locked_by_me(gl) == NULL) { if (mask & MAY_NOT_BLOCK) return -ECHILD; - error = gfs2_glock_nq_init(ip->i_gl, LM_ST_SHARED, LM_FLAG_ANY, &i_gh); + error = gfs2_glock_nq_init(gl, LM_ST_SHARED, LM_FLAG_ANY, &i_gh); if (error) return error; } diff --git a/fs/gfs2/super.c b/fs/gfs2/super.c index 44c564f0bc622..302d1e43d7012 100644 --- a/fs/gfs2/super.c +++ b/fs/gfs2/super.c @@ -1435,7 +1435,7 @@ static void gfs2_evict_inode(struct inode *inode) wait_on_bit_io(&ip->i_flags, GIF_GLOP_PENDING, TASK_UNINTERRUPTIBLE); gfs2_glock_add_to_lru(ip->i_gl); gfs2_glock_put_eventually(ip->i_gl); - ip->i_gl = NULL; + rcu_assign_pointer(ip->i_gl, NULL); } } -- 2.42.0