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 47891C4167D for ; Sun, 12 Nov 2023 13:30:59 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232069AbjKLNag (ORCPT ); Sun, 12 Nov 2023 08:30:36 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:37492 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231770AbjKLN2k (ORCPT ); Sun, 12 Nov 2023 08:28:40 -0500 Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id CA2B830F9; Sun, 12 Nov 2023 05:28:37 -0800 (PST) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 7EC88C433C8; Sun, 12 Nov 2023 13:28:36 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1699795717; bh=BsnINcb4SIYAU3XQfSnHpPrWAMzrUFIeLuv9ULrby3g=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=WOsvXclC5/y74kZ7EovwIERfXJB1Vt9dmkN3apP7kmMvATiFGrtmQDl8FQsu9KdLz by7Bc7YJkturkVJ35Wl11f5YrZymycQYqbwS6tiB81OgnNKF1f+mzUME2cJ9mCBS6B 5U7HJkJb/K5opAS6aEoB+fNbie5l9gFvojMObx0YvJZ/c2XtDllz/h152iK+DYpXGA eQJdI0cLlQlHs1iz/TrU75DKRR8Nkrf0yW2qFIMwkxTCnUyP5q64tD9vwMsDEjuzxS N+X8ovDahFsULJ3qwvrpbgMHxKl5oHcwa+Uh6TRdZ5LKiMQW2KvKnXacyXRG86ecjG 7qe2ZZUAGN1nA== 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 5.15 4/9] gfs2: fix an oops in gfs2_permission Date: Sun, 12 Nov 2023 08:28:24 -0500 Message-ID: <20231112132830.176228-4-sashal@kernel.org> X-Mailer: git-send-email 2.42.0 In-Reply-To: <20231112132830.176228-1-sashal@kernel.org> References: <20231112132830.176228-1-sashal@kernel.org> MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore X-stable-base: Linux 5.15.138 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 97ee17843b4d0..682418d9c8e72 100644 --- a/fs/gfs2/inode.c +++ b/fs/gfs2/inode.c @@ -1850,14 +1850,21 @@ 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 51b44da4a0d64..268651ac9fc84 100644 --- a/fs/gfs2/super.c +++ b/fs/gfs2/super.c @@ -1436,7 +1436,7 @@ 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