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=-6.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS, UNWANTED_LANGUAGE_BODY,URIBL_BLOCKED,USER_AGENT_GIT 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 3E661C04AB1 for ; Tue, 14 May 2019 03:23:30 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 12EC1208CA for ; Tue, 14 May 2019 03:23:30 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726718AbfENDX1 (ORCPT ); Mon, 13 May 2019 23:23:27 -0400 Received: from szxga07-in.huawei.com ([45.249.212.35]:52652 "EHLO huawei.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726379AbfENDX1 (ORCPT ); Mon, 13 May 2019 23:23:27 -0400 Received: from DGGEMS405-HUB.china.huawei.com (unknown [172.30.72.58]) by Forcepoint Email with ESMTP id 8EBABDA7448C347C207E; Tue, 14 May 2019 11:23:24 +0800 (CST) Received: from localhost.localdomain.localdomain (10.175.113.25) by DGGEMS405-HUB.china.huawei.com (10.3.19.205) with Microsoft SMTP Server id 14.3.439.0; Tue, 14 May 2019 11:23:14 +0800 From: Kefeng Wang To: , CC: Kefeng Wang , Peter Korsgaard , Shubhrajyoti Datta , "Greg Kroah-Hartman" , Hulk Robot Subject: [PATCH] tty: serial: uartlite: avoid null pointer dereference during rmmod Date: Tue, 14 May 2019 11:32:19 +0800 Message-ID: <20190514033219.169947-1-wangkefeng.wang@huawei.com> X-Mailer: git-send-email 2.20.1 MIME-Version: 1.0 Content-Transfer-Encoding: 7BIT Content-Type: text/plain; charset=US-ASCII X-Originating-IP: [10.175.113.25] X-CFilter-Loop: Reflected Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org After commit 415b43bdb008 "tty: serial: uartlite: Move uart register to probe", calling uart_unregister_driver unconditionally will trigger a null pointer dereference due to ulite_uart_driver may not registed. CPU: 1 PID: 3755 Comm: syz-executor.0 Not tainted 5.1.0+ #28 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.10.2-1ubuntu1 04/01/2014 Call Trace: __dump_stack lib/dump_stack.c:77 [inline] dump_stack+0xa9/0x10e lib/dump_stack.c:113 __kasan_report+0x171/0x18d mm/kasan/report.c:321 kasan_report+0xe/0x20 mm/kasan/common.c:614 tty_unregister_driver+0x19/0x100 drivers/tty/tty_io.c:3383 uart_unregister_driver+0x30/0xc0 drivers/tty/serial/serial_core.c:2579 __do_sys_delete_module kernel/module.c:1027 [inline] __se_sys_delete_module kernel/module.c:970 [inline] __x64_sys_delete_module+0x244/0x330 kernel/module.c:970 do_syscall_64+0x72/0x2a0 arch/x86/entry/common.c:298 entry_SYSCALL_64_after_hwframe+0x49/0xbe Call uart_unregister_driver only if ulite_uart_driver.state not null to fix it. Cc: Peter Korsgaard Cc: Shubhrajyoti Datta Cc: Greg Kroah-Hartman Reported-by: Hulk Robot Fixes: 415b43bdb008 ("tty: serial: uartlite: Move uart register to probe") Signed-off-by: Kefeng Wang --- drivers/tty/serial/uartlite.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/drivers/tty/serial/uartlite.c b/drivers/tty/serial/uartlite.c index b8b912b5a8b9..06e79c11141d 100644 --- a/drivers/tty/serial/uartlite.c +++ b/drivers/tty/serial/uartlite.c @@ -897,7 +897,8 @@ static int __init ulite_init(void) static void __exit ulite_exit(void) { platform_driver_unregister(&ulite_platform_driver); - uart_unregister_driver(&ulite_uart_driver); + if (ulite_uart_driver.state) + uart_unregister_driver(&ulite_uart_driver); } module_init(ulite_init); -- 2.20.1