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=-12.0 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, MENTIONS_GIT_HOSTING,SIGNED_OFF_BY,SPF_PASS autolearn=ham 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 9F360C10F03 for ; Thu, 25 Apr 2019 09:38:23 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 6C739218FE for ; Thu, 25 Apr 2019 09:38:23 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1556185103; bh=ePTwV0skujAUylg6p6U8V9YvtPuyynHxhnUeLs3CUqo=; h=Subject:To:From:Date:List-ID:From; b=XZyXw3whly9f1wC0i3kvo6Z+UQEgLA8HIR3jST9Bt9JVAuEXqGdvK6sIYhbLyVTqb G6WRM0OcipGWXwYNYTh7Roqfid8atd7e2NGrsT4ubYRR7ScCcLPzEzXUSyGTaqZMf/ jAdB56B8AsEsLRcF8FcwmO/U6zUdr3jVPg5RjIDk= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727969AbfDYJiX (ORCPT ); Thu, 25 Apr 2019 05:38:23 -0400 Received: from mail.kernel.org ([198.145.29.99]:33890 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726439AbfDYJiW (ORCPT ); Thu, 25 Apr 2019 05:38:22 -0400 Received: from localhost (62-193-50-229.as16211.net [62.193.50.229]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id D0F9E20685; Thu, 25 Apr 2019 09:38:20 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1556185101; bh=ePTwV0skujAUylg6p6U8V9YvtPuyynHxhnUeLs3CUqo=; h=Subject:To:From:Date:From; b=wHoz4XIGxOQQhEWRQB+6Z3lIWnPu60Ovx4HLwDHBgXKGt7bzyl9YivMta7rD35XDN TpykmhaLuQst2fIicS2F5KaSMU+07JMo8Pki+o0nHUE22vmlaUORixeUATgi4bSydL gbNSK7aOtiKsXPXZ7U70rAs4Dya4yZsM+82iJsAg= Subject: patch "TTY: serial_core, add ->install" added to tty-testing To: jslaby@suse.cz, gregkh@linuxfoundation.org, lirongqing@baidu.com, stable@vger.kernel.org, wangli39@baidu.com, zhangyu31@baidu.com From: Date: Thu, 25 Apr 2019 11:38:17 +0200 Message-ID: <1556185097105150@kroah.com> MIME-Version: 1.0 Content-Type: text/plain; charset=ANSI_X3.4-1968 Content-Transfer-Encoding: 8bit Sender: stable-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org This is a note to let you know that I've just added the patch titled TTY: serial_core, add ->install to my tty git tree which can be found at git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty.git in the tty-testing branch. The patch will show up in the next release of the linux-next tree (usually sometime within the next 24 hours during the week.) The patch will be merged to the tty-next branch sometime soon, after it passes testing, and the merge window is open. If you have any questions about this process, please let me know. >From 4cdd17ba1dff20ffc99fdbd2e6f0201fc7fe67df Mon Sep 17 00:00:00 2001 From: Jiri Slaby Date: Wed, 17 Apr 2019 10:58:53 +0200 Subject: TTY: serial_core, add ->install We need to compute the uart state only on the first open. This is usually what is done in the ->install hook. serial_core used to do this in ->open on every open. So move it to ->install. As a side effect, it ensures the state is set properly in the window after tty_init_dev is called, but before uart_open. This fixes a bunch of races between tty_open and flush_to_ldisc we were dealing with recently. One of such bugs was attempted to fix in commit fedb5760648a (serial: fix race between flush_to_ldisc and tty_open), but it only took care of a couple of functions (uart_start and uart_unthrottle). I was able to reproduce the crash on a SLE system, but in uart_write_room which is also called from flush_to_ldisc via process_echoes. I was *unable* to reproduce the bug locally. It is due to having this patch in my queue since 2012! general protection fault: 0000 [#1] SMP KASAN PTI CPU: 1 PID: 5 Comm: kworker/u4:0 Tainted: G L 4.12.14-396-default #1 SLE15-SP1 (unreleased) Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.12.0-0-ga698c89-prebuilt.qemu.org 04/01/2014 Workqueue: events_unbound flush_to_ldisc task: ffff8800427d8040 task.stack: ffff8800427f0000 RIP: 0010:uart_write_room+0xc4/0x590 RSP: 0018:ffff8800427f7088 EFLAGS: 00010202 RAX: dffffc0000000000 RBX: 0000000000000000 RCX: 0000000000000000 RDX: 000000000000002f RSI: 00000000000000ee RDI: ffff88003888bd90 RBP: ffffffffb9545850 R08: 0000000000000001 R09: 0000000000000400 R10: ffff8800427d825c R11: 000000000000006e R12: 1ffff100084fee12 R13: ffffc900004c5000 R14: ffff88003888bb28 R15: 0000000000000178 FS: 0000000000000000(0000) GS:ffff880043300000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000561da0794148 CR3: 000000000ebf4000 CR4: 00000000000006e0 Call Trace: tty_write_room+0x6d/0xc0 __process_echoes+0x55/0x870 n_tty_receive_buf_common+0x105e/0x26d0 tty_ldisc_receive_buf+0xb7/0x1c0 tty_port_default_receive_buf+0x107/0x180 flush_to_ldisc+0x35d/0x5c0 ... 0 in rbx means tty->driver_data is NULL in uart_write_room. 0x178 is tried to be dereferenced (0x178 >> 3 is 0x2f in rdx) at uart_write_room+0xc4. 0x178 is exactly (struct uart_state *)NULL->refcount used in uart_port_lock from uart_write_room. So revert the upstream commit here as my local patch should fix the whole family. Signed-off-by: Jiri Slaby Cc: Li RongQing Cc: Wang Li Cc: Zhang Yu Cc: Greg Kroah-Hartman Cc: stable Signed-off-by: Greg Kroah-Hartman --- drivers/tty/serial/serial_core.c | 24 +++++++++++++----------- 1 file changed, 13 insertions(+), 11 deletions(-) diff --git a/drivers/tty/serial/serial_core.c b/drivers/tty/serial/serial_core.c index 69f48717546b..0decb0bf991d 100644 --- a/drivers/tty/serial/serial_core.c +++ b/drivers/tty/serial/serial_core.c @@ -130,9 +130,6 @@ static void uart_start(struct tty_struct *tty) struct uart_port *port; unsigned long flags; - if (!state) - return; - port = uart_port_lock(state, flags); __uart_start(tty); uart_port_unlock(port, flags); @@ -730,9 +727,6 @@ static void uart_unthrottle(struct tty_struct *tty) upstat_t mask = UPSTAT_SYNC_FIFO; struct uart_port *port; - if (!state) - return; - port = uart_port_ref(state); if (!port) return; @@ -1747,6 +1741,16 @@ static void uart_dtr_rts(struct tty_port *port, int raise) uart_port_deref(uport); } +static int uart_install(struct tty_driver *driver, struct tty_struct *tty) +{ + struct uart_driver *drv = driver->driver_state; + struct uart_state *state = drv->state + tty->index; + + tty->driver_data = state; + + return tty_standard_install(driver, tty); +} + /* * Calls to uart_open are serialised by the tty_lock in * drivers/tty/tty_io.c:tty_open() @@ -1759,11 +1763,8 @@ static void uart_dtr_rts(struct tty_port *port, int raise) */ static int uart_open(struct tty_struct *tty, struct file *filp) { - struct uart_driver *drv = tty->driver->driver_state; - int retval, line = tty->index; - struct uart_state *state = drv->state + line; - - tty->driver_data = state; + struct uart_state *state = tty->driver_data; + int retval; retval = tty_port_open(&state->port, tty, filp); if (retval > 0) @@ -2448,6 +2449,7 @@ static void uart_poll_put_char(struct tty_driver *driver, int line, char ch) #endif static const struct tty_operations uart_ops = { + .install = uart_install, .open = uart_open, .close = uart_close, .write = uart_write, -- 2.21.0