From patchwork Mon Mar 13 22:12:29 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Eric Biggers X-Patchwork-Id: 13173390 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 3B3BBC61DA4 for ; Mon, 13 Mar 2023 22:15:01 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229776AbjCMWPA (ORCPT ); Mon, 13 Mar 2023 18:15:00 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:54596 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229743AbjCMWO7 (ORCPT ); Mon, 13 Mar 2023 18:14:59 -0400 Received: from ams.source.kernel.org (ams.source.kernel.org [145.40.68.75]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 67603637E5; Mon, 13 Mar 2023 15:14:58 -0700 (PDT) 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 ams.source.kernel.org (Postfix) with ESMTPS id 17A5AB81200; Mon, 13 Mar 2023 22:14:57 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id A3C12C4339B; Mon, 13 Mar 2023 22:14:55 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1678745695; bh=zvmdnOguTfDqdiHnoYELVOIodEHEhZGnF56sAJiM7Q4=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=CzVPS94eSnz40BVL80XJ1ikdaJ5Q9eWNwhszlVJVAMSTvhEVj+jtUZvZfykglblFl Z77i8g2BTkuZiMfLtiu+7kOSf7SYLWhQ3xYZiKFe1UrKzGHt9Je5GOq2alB+j2R9iy 4r6AREpNy87oiQfk+vysEfaaMCOtJ98YY70aCZGuEemnQ1oy07jVu+5AMo5KBu42pn J5VerWN7idgs1bfmM8AaHJgcLqP+i1ousYohJ4L2EDPT+gv7HxgpZl8H5nJE2ICm3r J3nfN16DQ0BjxNkZXQuAPtiFpX6Y8h2HIX0Nfkwv6w+oa7HXbN2tbY5cj2qD31hBCo uDDMGkQnX8DGg== From: Eric Biggers To: linux-fscrypt@vger.kernel.org Cc: linux-fsdevel@vger.kernel.org, linux-security-module@vger.kernel.org, stable@vger.kernel.org, syzbot+93e495f6a4f748827c88@syzkaller.appspotmail.com Subject: [PATCH 1/3] fscrypt: destroy keyring after security_sb_delete() Date: Mon, 13 Mar 2023 15:12:29 -0700 Message-Id: <20230313221231.272498-2-ebiggers@kernel.org> X-Mailer: git-send-email 2.39.2 In-Reply-To: <20230313221231.272498-1-ebiggers@kernel.org> References: <20230313221231.272498-1-ebiggers@kernel.org> MIME-Version: 1.0 Precedence: bulk List-ID: From: Eric Biggers fscrypt_destroy_keyring() must be called after all potentially-encrypted inodes were evicted; otherwise it cannot safely destroy the keyring. Since inodes that are in-use by the Landlock LSM don't get evicted until security_sb_delete(), this means that fscrypt_destroy_keyring() must be called *after* security_sb_delete(). This fixes a WARN_ON followed by a NULL dereference, only possible if Landlock was being used on encrypted files. Fixes: d7e7b9af104c ("fscrypt: stop using keyrings subsystem for fscrypt_master_key") Cc: stable@vger.kernel.org Reported-by: syzbot+93e495f6a4f748827c88@syzkaller.appspotmail.com Link: https://lore.kernel.org/r/00000000000044651705f6ca1e30@google.com Signed-off-by: Eric Biggers Reviewed-by: Christian Brauner --- fs/super.c | 15 ++++++++++++--- 1 file changed, 12 insertions(+), 3 deletions(-) diff --git a/fs/super.c b/fs/super.c index 84332d5cb817a..04bc62ab7dfea 100644 --- a/fs/super.c +++ b/fs/super.c @@ -475,13 +475,22 @@ void generic_shutdown_super(struct super_block *sb) cgroup_writeback_umount(); - /* evict all inodes with zero refcount */ + /* Evict all inodes with zero refcount. */ evict_inodes(sb); - /* only nonzero refcount inodes can have marks */ + + /* + * Clean up and evict any inodes that still have references due + * to fsnotify or the security policy. + */ fsnotify_sb_delete(sb); - fscrypt_destroy_keyring(sb); security_sb_delete(sb); + /* + * Now that all potentially-encrypted inodes have been evicted, + * the fscrypt keyring can be destroyed. + */ + fscrypt_destroy_keyring(sb); + if (sb->s_dio_done_wq) { destroy_workqueue(sb->s_dio_done_wq); sb->s_dio_done_wq = NULL;