From patchwork Fri Apr 29 10:41:19 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Greg Kroah-Hartman X-Patchwork-Id: 568535 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 429BEC4332F for ; Fri, 29 Apr 2022 10:41:56 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1357660AbiD2KpL (ORCPT ); Fri, 29 Apr 2022 06:45:11 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:57968 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1357680AbiD2KpK (ORCPT ); Fri, 29 Apr 2022 06:45:10 -0400 Received: from ams.source.kernel.org (ams.source.kernel.org [145.40.68.75]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 7FE0BC1C83; Fri, 29 Apr 2022 03:41:52 -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 20CB2B8301B; Fri, 29 Apr 2022 10:41:51 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 4A3C4C385A7; Fri, 29 Apr 2022 10:41:49 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1651228909; bh=iYR/JQoXCV7XX5ZZ+TJkr0jQjj9qQIX2MFkcbv0kXqs=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=uswmFYBN5pZVaqRNHumAzYtLOIatLLi7kT1JkxiJxwKMCcVuahygj6sIIl7eMr5uT +ekrnRyL/0O5m5Dx930bu1jtt1N85Zeu6VN7Fz3KnEPav02cl8O7owbB4udN9hIHpc 6F9IcoZta8TZuNTGinmHyHjGW7PIp6Byi8el8Aw0= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Minh Yuan , syzbot+8e8958586909d62b6840@syzkaller.appspotmail.com, cruise k , Kyungtae Kim , Linus Torvalds , Denis Efremov , Willy Tarreau , Linus Torvalds Subject: [PATCH 4.19 02/12] floppy: disable FDRAWCMD by default Date: Fri, 29 Apr 2022 12:41:19 +0200 Message-Id: <20220429104048.531834070@linuxfoundation.org> X-Mailer: git-send-email 2.36.0 In-Reply-To: <20220429104048.459089941@linuxfoundation.org> References: <20220429104048.459089941@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Willy Tarreau commit 233087ca063686964a53c829d547c7571e3f67bf upstream. Minh Yuan reported a concurrency use-after-free issue in the floppy code between raw_cmd_ioctl and seek_interrupt. [ It turns out this has been around, and that others have reported the KASAN splats over the years, but Minh Yuan had a reproducer for it and so gets primary credit for reporting it for this fix - Linus ] The problem is, this driver tends to break very easily and nowadays, nobody is expected to use FDRAWCMD anyway since it was used to manipulate non-standard formats. The risk of breaking the driver is higher than the risk presented by this race, and accessing the device requires privileges anyway. Let's just add a config option to completely disable this ioctl and leave it disabled by default. Distros shouldn't use it, and only those running on antique hardware might need to enable it. Link: https://lore.kernel.org/all/000000000000b71cdd05d703f6bf@google.com/ Link: https://lore.kernel.org/lkml/CAKcFiNC=MfYVW-Jt9A3=FPJpTwCD2PL_ULNCpsCVE5s8ZeBQgQ@mail.gmail.com Link: https://lore.kernel.org/all/CAEAjamu1FRhz6StCe_55XY5s389ZP_xmCF69k987En+1z53=eg@mail.gmail.com Reported-by: Minh Yuan Reported-by: syzbot+8e8958586909d62b6840@syzkaller.appspotmail.com Reported-by: cruise k Reported-by: Kyungtae Kim Suggested-by: Linus Torvalds Tested-by: Denis Efremov Signed-off-by: Willy Tarreau Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman --- drivers/block/Kconfig | 16 ++++++++++++++++ drivers/block/floppy.c | 43 ++++++++++++++++++++++++++++++++----------- 2 files changed, 48 insertions(+), 11 deletions(-) --- a/drivers/block/Kconfig +++ b/drivers/block/Kconfig @@ -39,6 +39,22 @@ config BLK_DEV_FD To compile this driver as a module, choose M here: the module will be called floppy. +config BLK_DEV_FD_RAWCMD + bool "Support for raw floppy disk commands (DEPRECATED)" + depends on BLK_DEV_FD + help + If you want to use actual physical floppies and expect to do + special low-level hardware accesses to them (access and use + non-standard formats, for example), then enable this. + + Note that the code enabled by this option is rarely used and + might be unstable or insecure, and distros should not enable it. + + Note: FDRAWCMD is deprecated and will be removed from the kernel + in the near future. + + If unsure, say N. + config AMIGA_FLOPPY tristate "Amiga floppy support" depends on AMIGA --- a/drivers/block/floppy.c +++ b/drivers/block/floppy.c @@ -3023,6 +3023,8 @@ static const char *drive_name(int type, return "(null)"; } +#ifdef CONFIG_BLK_DEV_FD_RAWCMD + /* raw commands */ static void raw_cmd_done(int flag) { @@ -3234,6 +3236,35 @@ static int raw_cmd_ioctl(int cmd, void _ return ret; } +static int floppy_raw_cmd_ioctl(int type, int drive, int cmd, + void __user *param) +{ + int ret; + + pr_warn_once("Note: FDRAWCMD is deprecated and will be removed from the kernel in the near future.\n"); + + if (type) + return -EINVAL; + if (lock_fdc(drive)) + return -EINTR; + set_floppy(drive); + ret = raw_cmd_ioctl(cmd, param); + if (ret == -EINTR) + return -EINTR; + process_fd_request(); + return ret; +} + +#else /* CONFIG_BLK_DEV_FD_RAWCMD */ + +static int floppy_raw_cmd_ioctl(int type, int drive, int cmd, + void __user *param) +{ + return -EOPNOTSUPP; +} + +#endif + static int invalidate_drive(struct block_device *bdev) { /* invalidate the buffer track to force a reread */ @@ -3421,7 +3452,6 @@ static int fd_locked_ioctl(struct block_ { int drive = (long)bdev->bd_disk->private_data; int type = ITYPE(UDRS->fd_device); - int i; int ret; int size; union inparam { @@ -3572,16 +3602,7 @@ static int fd_locked_ioctl(struct block_ outparam = UDRWE; break; case FDRAWCMD: - if (type) - return -EINVAL; - if (lock_fdc(drive)) - return -EINTR; - set_floppy(drive); - i = raw_cmd_ioctl(cmd, (void __user *)param); - if (i == -EINTR) - return -EINTR; - process_fd_request(); - return i; + return floppy_raw_cmd_ioctl(type, drive, cmd, (void __user *)param); case FDTWADDLE: if (lock_fdc(drive)) return -EINTR;