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 C4111C678D5 for ; Tue, 7 Mar 2023 17:44:31 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232050AbjCGRoa (ORCPT ); Tue, 7 Mar 2023 12:44:30 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:54118 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232052AbjCGRoP (ORCPT ); Tue, 7 Mar 2023 12:44:15 -0500 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 8113E95E02 for ; Tue, 7 Mar 2023 09:39:59 -0800 (PST) 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 dfw.source.kernel.org (Postfix) with ESMTPS id F24086150C for ; Tue, 7 Mar 2023 17:39:09 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 16A41C433D2; Tue, 7 Mar 2023 17:39:08 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1678210749; bh=pYmPZuIatWJIy9TjbQpRfMHAueHd4doPOek4LgFFMPE=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=K3UQRsZ7dNAfpJPCwSFlwG6uYsUOVHm/ZREhpacQQUipSgO8CYC8TnBd61RG7evED AE+mJwxmdho05K4MAKxjYHtS2mqRonJMxJ9oJgzrxsn8RXjETvnK+m0QGo4zlhDvFr qqX7XqiTgpe+LdZh8HKqsoXI8OW2/H7yp4VKiSjE= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Jann Horn , "Christian Brauner (Microsoft)" , Kees Cook , Sasha Levin Subject: [PATCH 6.2 0624/1001] fs: Use CHECK_DATA_CORRUPTION() when kernel bugs are detected Date: Tue, 7 Mar 2023 17:56:36 +0100 Message-Id: <20230307170048.642209949@linuxfoundation.org> X-Mailer: git-send-email 2.39.2 In-Reply-To: <20230307170022.094103862@linuxfoundation.org> References: <20230307170022.094103862@linuxfoundation.org> User-Agent: quilt/0.67 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Jann Horn [ Upstream commit 47d586913f2abec4d240bae33417f537fda987ec ] Currently, filp_close() and generic_shutdown_super() use printk() to log messages when bugs are detected. This is problematic because infrastructure like syzkaller has no idea that this message indicates a bug. In addition, some people explicitly want their kernels to BUG() when kernel data corruption has been detected (CONFIG_BUG_ON_DATA_CORRUPTION). And finally, when generic_shutdown_super() detects remaining inodes on a system without CONFIG_BUG_ON_DATA_CORRUPTION, it would be nice if later accesses to a busy inode would at least crash somewhat cleanly rather than walking through freed memory. To address all three, use CHECK_DATA_CORRUPTION() when kernel bugs are detected. Signed-off-by: Jann Horn Reviewed-by: Christian Brauner (Microsoft) Reviewed-by: Kees Cook Signed-off-by: Christian Brauner (Microsoft) Signed-off-by: Sasha Levin --- fs/open.c | 5 +++-- fs/super.c | 21 +++++++++++++++++---- include/linux/poison.h | 3 +++ 3 files changed, 23 insertions(+), 6 deletions(-) diff --git a/fs/open.c b/fs/open.c index 82c1a28b33089..ceb88ac0ca3b2 100644 --- a/fs/open.c +++ b/fs/open.c @@ -1411,8 +1411,9 @@ int filp_close(struct file *filp, fl_owner_t id) { int retval = 0; - if (!file_count(filp)) { - printk(KERN_ERR "VFS: Close: file count is 0\n"); + if (CHECK_DATA_CORRUPTION(file_count(filp) == 0, + "VFS: Close: file count is 0 (f_op=%ps)", + filp->f_op)) { return 0; } diff --git a/fs/super.c b/fs/super.c index 12c08cb20405d..cf737ec2bd05c 100644 --- a/fs/super.c +++ b/fs/super.c @@ -491,10 +491,23 @@ void generic_shutdown_super(struct super_block *sb) if (sop->put_super) sop->put_super(sb); - if (!list_empty(&sb->s_inodes)) { - printk("VFS: Busy inodes after unmount of %s. " - "Self-destruct in 5 seconds. Have a nice day...\n", - sb->s_id); + if (CHECK_DATA_CORRUPTION(!list_empty(&sb->s_inodes), + "VFS: Busy inodes after unmount of %s (%s)", + sb->s_id, sb->s_type->name)) { + /* + * Adding a proper bailout path here would be hard, but + * we can at least make it more likely that a later + * iput_final() or such crashes cleanly. + */ + struct inode *inode; + + spin_lock(&sb->s_inode_list_lock); + list_for_each_entry(inode, &sb->s_inodes, i_sb_list) { + inode->i_op = VFS_PTR_POISON; + inode->i_sb = VFS_PTR_POISON; + inode->i_mapping = VFS_PTR_POISON; + } + spin_unlock(&sb->s_inode_list_lock); } } spin_lock(&sb_lock); diff --git a/include/linux/poison.h b/include/linux/poison.h index 2d3249eb0e62d..0e8a1f2ceb2f1 100644 --- a/include/linux/poison.h +++ b/include/linux/poison.h @@ -84,4 +84,7 @@ /********** kernel/bpf/ **********/ #define BPF_PTR_POISON ((void *)(0xeB9FUL + POISON_POINTER_DELTA)) +/********** VFS **********/ +#define VFS_PTR_POISON ((void *)(0xF5 + POISON_POINTER_DELTA)) + #endif -- 2.39.2