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 X-Spam-Level: X-Spam-Status: No, score=-19.4 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_GIT autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id B0A3DC2BA09 for ; Mon, 10 May 2021 11:00:47 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 7FAA66199B for ; Mon, 10 May 2021 11:00:47 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235188AbhEJLAX (ORCPT ); Mon, 10 May 2021 07:00:23 -0400 Received: from mail.kernel.org ([198.145.29.99]:59426 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233165AbhEJKpQ (ORCPT ); Mon, 10 May 2021 06:45:16 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 9009361920; Mon, 10 May 2021 10:35:01 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1620642902; bh=iZEWfYJtKNoiNtsC6AnuMN0x/0Nu1KgcY2pn0H4HLyg=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=Z64YL5xnXyGI8LnakfR1VfAQ9wDtqKDThF8f9MNSpfVvoNm5Tihsev21tkuUXR3bf Zl2a33B2x4PdF7xJ9MoRscaTe+3zls0u0a3Qw+/IzELWwSem5QFK48S/tvy3pj2pEQ Sw+V+gDGtKTBIppl9sY7IG4KHOVYx300Vok/KEZs= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, syzbot+c49fe6089f295a05e6f8@syzkaller.appspotmail.com, Hillf Danton , Sasha Levin , Hao Sun Subject: [PATCH 5.10 099/299] tty: n_gsm: check error while registering tty devices Date: Mon, 10 May 2021 12:18:16 +0200 Message-Id: <20210510102008.206495617@linuxfoundation.org> X-Mailer: git-send-email 2.31.1 In-Reply-To: <20210510102004.821838356@linuxfoundation.org> References: <20210510102004.821838356@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Hillf Danton [ Upstream commit 0a360e8b65d62fe1a994f0a8da4f8d20877b2100 ] Add the error path for registering tty devices and roll back in case of error in bid to avoid the UAF like the below one reported. Plus syzbot reported general protection fault in cdev_del() on Sep 24, 2020 and both cases are down to the kobject_put() in tty_cdev_add(). ------------[ cut here ]------------ refcount_t: underflow; use-after-free. WARNING: CPU: 1 PID: 8923 at lib/refcount.c:28 refcount_warn_saturate+0x1cf/0x210 -origin/lib/refcount.c:28 Modules linked in: CPU: 1 PID: 8923 Comm: executor Not tainted 5.12.0-rc5+ #8 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.13.0-1ubuntu1.1 04/01/2014 RIP: 0010:refcount_warn_saturate+0x1cf/0x210 -origin/lib/refcount.c:28 Code: 4f ff ff ff e8 32 fa b5 fe 48 c7 c7 3d f8 f6 86 e8 d6 ab c6 fe c6 05 7c 34 67 04 01 48 c7 c7 68 f8 6d 86 31 c0 e8 81 2e 9d fe <0f> 0b e9 22 ff ff ff e8 05 fa b5 fe 48 c7 c7 3e f8 f6 86 e8 a9 ab RSP: 0018:ffffc90001633c60 EFLAGS: 00010246 RAX: 15d08b2e34b77800 RBX: 0000000000000003 RCX: ffff88804c056c80 RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000 RBP: 0000000000000003 R08: ffffffff813767aa R09: 0001ffffffffffff R10: 0001ffffffffffff R11: ffff88804c056c80 R12: ffff888040b7d000 R13: ffff88804c206938 R14: ffff88804c206900 R15: ffff888041b18488 FS: 00000000022c9940(0000) GS:ffff88807ec00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f9f9b122008 CR3: 0000000044b4b000 CR4: 0000000000750ee0 PKRU: 55555554 Call Trace: __refcount_sub_and_test -origin/./include/linux/refcount.h:283 [inline] __refcount_dec_and_test -origin/./include/linux/refcount.h:315 [inline] refcount_dec_and_test -origin/./include/linux/refcount.h:333 [inline] kref_put -origin/./include/linux/kref.h:64 [inline] kobject_put+0x17b/0x180 -origin/lib/kobject.c:753 cdev_del+0x4b/0x50 -origin/fs/char_dev.c:597 tty_unregister_device+0x99/0xd0 -origin/drivers/tty/tty_io.c:3343 gsmld_detach_gsm -origin/drivers/tty/n_gsm.c:2409 [inline] gsmld_close+0x6c/0x140 -origin/drivers/tty/n_gsm.c:2478 tty_ldisc_close -origin/drivers/tty/tty_ldisc.c:488 [inline] tty_ldisc_kill -origin/drivers/tty/tty_ldisc.c:636 [inline] tty_ldisc_release+0x1b6/0x400 -origin/drivers/tty/tty_ldisc.c:809 tty_release_struct+0x19/0xb0 -origin/drivers/tty/tty_io.c:1714 tty_release+0x9ad/0xa00 -origin/drivers/tty/tty_io.c:1885 __fput+0x260/0x4e0 -origin/fs/file_table.c:280 ____fput+0x11/0x20 -origin/fs/file_table.c:313 task_work_run+0x8e/0x110 -origin/kernel/task_work.c:140 tracehook_notify_resume -origin/./include/linux/tracehook.h:189 [inline] exit_to_user_mode_loop -origin/kernel/entry/common.c:174 [inline] exit_to_user_mode_prepare+0x16b/0x1a0 -origin/kernel/entry/common.c:208 __syscall_exit_to_user_mode_work -origin/kernel/entry/common.c:290 [inline] syscall_exit_to_user_mode+0x20/0x40 -origin/kernel/entry/common.c:301 do_syscall_64+0x45/0x80 -origin/arch/x86/entry/common.c:56 entry_SYSCALL_64_after_hwframe+0x44/0xae Reported-by: syzbot+c49fe6089f295a05e6f8@syzkaller.appspotmail.com Reported-and-tested-by: Hao Sun Signed-off-by: Hillf Danton Link: https://lore.kernel.org/r/20210412035758.1974-1-hdanton@sina.com Signed-off-by: Greg Kroah-Hartman Signed-off-by: Sasha Levin --- drivers/tty/n_gsm.c | 14 ++++++++++++-- 1 file changed, 12 insertions(+), 2 deletions(-) diff --git a/drivers/tty/n_gsm.c b/drivers/tty/n_gsm.c index fea1eeac5b90..d76880ae68c8 100644 --- a/drivers/tty/n_gsm.c +++ b/drivers/tty/n_gsm.c @@ -2382,8 +2382,18 @@ static int gsmld_attach_gsm(struct tty_struct *tty, struct gsm_mux *gsm) /* Don't register device 0 - this is the control channel and not a usable tty interface */ base = mux_num_to_base(gsm); /* Base for this MUX */ - for (i = 1; i < NUM_DLCI; i++) - tty_register_device(gsm_tty_driver, base + i, NULL); + for (i = 1; i < NUM_DLCI; i++) { + struct device *dev; + + dev = tty_register_device(gsm_tty_driver, + base + i, NULL); + if (IS_ERR(dev)) { + for (i--; i >= 1; i--) + tty_unregister_device(gsm_tty_driver, + base + i); + return PTR_ERR(dev); + } + } } return ret; } -- 2.30.2