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=-13.1 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,URIBL_BLOCKED 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 30555C43387 for ; Fri, 18 Jan 2019 12:09:37 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 010C72087E for ; Fri, 18 Jan 2019 12:09:37 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1547813377; bh=7oNqIhhNXtr4TsQFYI9iOMv0q0dejJ7CC9pt0778xWY=; h=Subject:To:From:Date:List-ID:From; b=dgQN3ODPW144nBzoao9mgLyG0I2F7Wy7A7sqLRCkX04KpIox8PK7pvTgUxM5WaxzX s9z6Fd5Teokofiq+xX9a9aHn2txJSeoTw9jkhBOcF0xdByO8sq8AKT9VZQ3OPITN7o 4kdzP0Bwye+V230/9oMACNJeeRUrfl7ktxSVZdCg= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727458AbfARMJg (ORCPT ); Fri, 18 Jan 2019 07:09:36 -0500 Received: from mail.kernel.org ([198.145.29.99]:42310 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727334AbfARMJg (ORCPT ); Fri, 18 Jan 2019 07:09:36 -0500 Received: from localhost (5356596B.cm-6-7b.dynamic.ziggo.nl [83.86.89.107]) (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 B163E2087E; Fri, 18 Jan 2019 12:09:34 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1547813375; bh=7oNqIhhNXtr4TsQFYI9iOMv0q0dejJ7CC9pt0778xWY=; h=Subject:To:From:Date:From; b=MvrHgFHocOw016rsukstn2J9u+NBk+DYOTt45/RXyafDvkanfYdI4MQL3YCTMaiuj 7L6zLPUzZ+Bobt3Y6DR8QpYrNL0svR7mAbB3M5hU2vmh+WsRJcmVZNLVLDhjKSY7PO qvuKTEsLxj88/OK7jNVKx8iW0L+aF1bGxe3z9zo0= Subject: patch "uart: Fix crash in uart_write and uart_put_char" added to tty-linus To: samir@embedur.com, gregkh@linuxfoundation.org, stable@vger.kernel.org, tycho@tycho.ws From: Date: Fri, 18 Jan 2019 13:09:32 +0100 Message-ID: <154781337222451@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 uart: Fix crash in uart_write and uart_put_char 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-linus 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 hopefully also be merged in Linus's tree for the next -rc kernel release. If you have any questions about this process, please let me know. >From aff9cf5955185d1f183227e46c5f8673fa483813 Mon Sep 17 00:00:00 2001 From: Samir Virmani Date: Wed, 16 Jan 2019 10:28:07 -0800 Subject: uart: Fix crash in uart_write and uart_put_char We were experiencing a crash similar to the one reported as part of commit:a5ba1d95e46e ("uart: fix race between uart_put_char() and uart_shutdown()") in our testbed as well. We continue to observe the same crash after integrating the commit a5ba1d95e46e ("uart: fix race between uart_put_char() and uart_shutdown()") On reviewing the change, the port lock should be taken prior to checking for if (!circ->buf) in fn. __uart_put_char and other fns. that update the buffer uart_state->xmit. Traceback: [11/27/2018 06:24:32.4870] Unable to handle kernel NULL pointer dereference at virtual address 0000003b [11/27/2018 06:24:32.4950] PC is at memcpy+0x48/0x180 [11/27/2018 06:24:32.4950] LR is at uart_write+0x74/0x120 [11/27/2018 06:24:32.4950] pc : [] lr : [] pstate: 000001c5 [11/27/2018 06:24:32.4950] sp : ffffffc076433d30 [11/27/2018 06:24:32.4950] x29: ffffffc076433d30 x28: 0000000000000140 [11/27/2018 06:24:32.4950] x27: ffffffc0009b9d5e x26: ffffffc07ce36580 [11/27/2018 06:24:32.4950] x25: 0000000000000000 x24: 0000000000000140 [11/27/2018 06:24:32.4950] x23: ffffffc000891200 x22: ffffffc01fc34000 [11/27/2018 06:24:32.4950] x21: 0000000000000fff x20: 0000000000000076 [11/27/2018 06:24:32.4950] x19: 0000000000000076 x18: 0000000000000000 [11/27/2018 06:24:32.4950] x17: 000000000047cf08 x16: ffffffc000099e68 [11/27/2018 06:24:32.4950] x15: 0000000000000018 x14: 776d726966205948 [11/27/2018 06:24:32.4950] x13: 50203a6c6974755f x12: 74647075205d3333 [11/27/2018 06:24:32.4950] x11: 3a35323a36203831 x10: 30322f37322f3131 [11/27/2018 06:24:32.4950] x9 : 5b205d303638342e x8 : 746164206f742070 [11/27/2018 06:24:32.4950] x7 : 7520736920657261 x6 : 000000000000003b [11/27/2018 06:24:32.4950] x5 : 000000000000817a x4 : 0000000000000008 [11/27/2018 06:24:32.4950] x3 : 2f37322f31312a5b x2 : 000000000000006e [11/27/2018 06:24:32.4950] x1 : ffffffc0009b9cf0 x0 : 000000000000003b [11/27/2018 06:24:32.4950] CPU2: stopping [11/27/2018 06:24:32.4950] CPU: 2 PID: 0 Comm: swapper/2 Tainted: P D O 4.1.51 #3 [11/27/2018 06:24:32.4950] Hardware name: Broadcom-v8A (DT) [11/27/2018 06:24:32.4950] Call trace: [11/27/2018 06:24:32.4950] [] dump_backtrace+0x0/0x150 [11/27/2018 06:24:32.4950] [] show_stack+0x14/0x20 [11/27/2018 06:24:32.4950] [] dump_stack+0x90/0xb0 [11/27/2018 06:24:32.4950] [] handle_IPI+0x18c/0x1a0 [11/27/2018 06:24:32.4950] [] gic_handle_irq+0x88/0x90 Fixes: a5ba1d95e46e ("uart: fix race between uart_put_char() and uart_shutdown()") Cc: stable Signed-off-by: Samir Virmani Acked-by: Tycho Andersen Signed-off-by: Greg Kroah-Hartman --- drivers/tty/serial/serial_core.c | 12 ++++++++---- 1 file changed, 8 insertions(+), 4 deletions(-) diff --git a/drivers/tty/serial/serial_core.c b/drivers/tty/serial/serial_core.c index d4cca5bdaf1c..5c01bb6d1c24 100644 --- a/drivers/tty/serial/serial_core.c +++ b/drivers/tty/serial/serial_core.c @@ -550,10 +550,12 @@ static int uart_put_char(struct tty_struct *tty, unsigned char c) int ret = 0; circ = &state->xmit; - if (!circ->buf) + port = uart_port_lock(state, flags); + if (!circ->buf) { + uart_port_unlock(port, flags); return 0; + } - port = uart_port_lock(state, flags); if (port && uart_circ_chars_free(circ) != 0) { circ->buf[circ->head] = c; circ->head = (circ->head + 1) & (UART_XMIT_SIZE - 1); @@ -586,11 +588,13 @@ static int uart_write(struct tty_struct *tty, return -EL3HLT; } + port = uart_port_lock(state, flags); circ = &state->xmit; - if (!circ->buf) + if (!circ->buf) { + uart_port_unlock(port, flags); return 0; + } - port = uart_port_lock(state, flags); while (port) { c = CIRC_SPACE_TO_END(circ->head, circ->tail, UART_XMIT_SIZE); if (count < c) -- 2.20.1