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=-9.6 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_PASS,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 3025AECDE44 for ; Sun, 4 Nov 2018 13:54:08 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id E54142085B for ; Sun, 4 Nov 2018 13:54:07 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=kernel.org header.i=@kernel.org header.b="wbsCFri1" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org E54142085B Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731534AbeKDXJJ (ORCPT ); Sun, 4 Nov 2018 18:09:09 -0500 Received: from mail.kernel.org ([198.145.29.99]:48548 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729578AbeKDXJH (ORCPT ); Sun, 4 Nov 2018 18:09:07 -0500 Received: from sasha-vm.mshome.net (c-73-47-72-35.hsd1.nh.comcast.net [73.47.72.35]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id B70902086D; Sun, 4 Nov 2018 13:54:01 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1541339642; bh=mFpQBVEXwrVfO/FnSbCHSTTF0qKNKI+iuy5ITP0vT5c=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=wbsCFri1FsC0qWHcxEBBHJpmy4vkQUryVpdBZSM51TBEL+TCV/dEuGn9TpEbSEbkx YTiUOl+K8IXb61aw++mQztFvkDINMmBv7q1nE9FE4VEI1o5+yAs+n+YdpMp36JjRDQ yQpt33IyXkHJ5w5FIVIyYp8PxXB/a9WN9KCzpDMo= From: Sasha Levin To: stable@vger.kernel.org, linux-kernel@vger.kernel.org Cc: Miles Chen , Greg Kroah-Hartman , Sasha Levin Subject: [PATCH AUTOSEL 4.9 05/21] tty: check name length in tty_find_polling_driver() Date: Sun, 4 Nov 2018 08:53:39 -0500 Message-Id: <20181104135355.88602-5-sashal@kernel.org> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20181104135355.88602-1-sashal@kernel.org> References: <20181104135355.88602-1-sashal@kernel.org> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Miles Chen [ Upstream commit 33a1a7be198657c8ca26ad406c4d2a89b7162bcc ] The issue is found by a fuzzing test. If tty_find_polling_driver() recevies an incorrect input such as ',,' or '0b', the len becomes 0 and strncmp() always return 0. In this case, a null p->ops->poll_init() is called and it causes a kernel panic. Fix this by checking name length against zero in tty_find_polling_driver(). $echo ,, > /sys/module/kgdboc/parameters/kgdboc [ 20.804451] WARNING: CPU: 1 PID: 104 at drivers/tty/serial/serial_core.c:457 uart_get_baud_rate+0xe8/0x190 [ 20.804917] Modules linked in: [ 20.805317] CPU: 1 PID: 104 Comm: sh Not tainted 4.19.0-rc7ajb #8 [ 20.805469] Hardware name: linux,dummy-virt (DT) [ 20.805732] pstate: 20000005 (nzCv daif -PAN -UAO) [ 20.805895] pc : uart_get_baud_rate+0xe8/0x190 [ 20.806042] lr : uart_get_baud_rate+0xc0/0x190 [ 20.806476] sp : ffffffc06acff940 [ 20.806676] x29: ffffffc06acff940 x28: 0000000000002580 [ 20.806977] x27: 0000000000009600 x26: 0000000000009600 [ 20.807231] x25: ffffffc06acffad0 x24: 00000000ffffeff0 [ 20.807576] x23: 0000000000000001 x22: 0000000000000000 [ 20.807807] x21: 0000000000000001 x20: 0000000000000000 [ 20.808049] x19: ffffffc06acffac8 x18: 0000000000000000 [ 20.808277] x17: 0000000000000000 x16: 0000000000000000 [ 20.808520] x15: ffffffffffffffff x14: ffffffff00000000 [ 20.808757] x13: ffffffffffffffff x12: 0000000000000001 [ 20.809011] x11: 0101010101010101 x10: ffffff880d59ff5f [ 20.809292] x9 : ffffff880d59ff5e x8 : ffffffc06acffaf3 [ 20.809549] x7 : 0000000000000000 x6 : ffffff880d59ff5f [ 20.809803] x5 : 0000000080008001 x4 : 0000000000000003 [ 20.810056] x3 : ffffff900853e6b4 x2 : dfffff9000000000 [ 20.810693] x1 : ffffffc06acffad0 x0 : 0000000000000cb0 [ 20.811005] Call trace: [ 20.811214] uart_get_baud_rate+0xe8/0x190 [ 20.811479] serial8250_do_set_termios+0xe0/0x6f4 [ 20.811719] serial8250_set_termios+0x48/0x54 [ 20.811928] uart_set_options+0x138/0x1bc [ 20.812129] uart_poll_init+0x114/0x16c [ 20.812330] tty_find_polling_driver+0x158/0x200 [ 20.812545] configure_kgdboc+0xbc/0x1bc [ 20.812745] param_set_kgdboc_var+0xb8/0x150 [ 20.812960] param_attr_store+0xbc/0x150 [ 20.813160] module_attr_store+0x40/0x58 [ 20.813364] sysfs_kf_write+0x8c/0xa8 [ 20.813563] kernfs_fop_write+0x154/0x290 [ 20.813764] vfs_write+0xf0/0x278 [ 20.813951] __arm64_sys_write+0x84/0xf4 [ 20.814400] el0_svc_common+0xf4/0x1dc [ 20.814616] el0_svc_handler+0x98/0xbc [ 20.814804] el0_svc+0x8/0xc [ 20.822005] Unable to handle kernel NULL pointer dereference at virtual address 0000000000000000 [ 20.826913] Mem abort info: [ 20.827103] ESR = 0x84000006 [ 20.827352] Exception class = IABT (current EL), IL = 16 bits [ 20.827655] SET = 0, FnV = 0 [ 20.827855] EA = 0, S1PTW = 0 [ 20.828135] user pgtable: 4k pages, 39-bit VAs, pgdp = (____ptrval____) [ 20.828484] [0000000000000000] pgd=00000000aadee003, pud=00000000aadee003, pmd=0000000000000000 [ 20.829195] Internal error: Oops: 84000006 [#1] SMP [ 20.829564] Modules linked in: [ 20.829890] CPU: 1 PID: 104 Comm: sh Tainted: G W 4.19.0-rc7ajb #8 [ 20.830545] Hardware name: linux,dummy-virt (DT) [ 20.830829] pstate: 60000085 (nZCv daIf -PAN -UAO) [ 20.831174] pc : (null) [ 20.831457] lr : serial8250_do_set_termios+0x358/0x6f4 [ 20.831727] sp : ffffffc06acff9b0 [ 20.831936] x29: ffffffc06acff9b0 x28: ffffff9008d7c000 [ 20.832267] x27: ffffff900969e16f x26: 0000000000000000 [ 20.832589] x25: ffffff900969dfb0 x24: 0000000000000000 [ 20.832906] x23: ffffffc06acffad0 x22: ffffff900969e160 [ 20.833232] x21: 0000000000000000 x20: ffffffc06acffac8 [ 20.833559] x19: ffffff900969df90 x18: 0000000000000000 [ 20.833878] x17: 0000000000000000 x16: 0000000000000000 [ 20.834491] x15: ffffffffffffffff x14: ffffffff00000000 [ 20.834821] x13: ffffffffffffffff x12: 0000000000000001 [ 20.835143] x11: 0101010101010101 x10: ffffff880d59ff5f [ 20.835467] x9 : ffffff880d59ff5e x8 : ffffffc06acffaf3 [ 20.835790] x7 : 0000000000000000 x6 : ffffff880d59ff5f [ 20.836111] x5 : c06419717c314100 x4 : 0000000000000007 [ 20.836419] x3 : 0000000000000000 x2 : 0000000000000000 [ 20.836732] x1 : 0000000000000001 x0 : ffffff900969df90 [ 20.837100] Process sh (pid: 104, stack limit = 0x(____ptrval____)) [ 20.837396] Call trace: [ 20.837566] (null) [ 20.837816] serial8250_set_termios+0x48/0x54 [ 20.838089] uart_set_options+0x138/0x1bc [ 20.838570] uart_poll_init+0x114/0x16c [ 20.838834] tty_find_polling_driver+0x158/0x200 [ 20.839119] configure_kgdboc+0xbc/0x1bc [ 20.839380] param_set_kgdboc_var+0xb8/0x150 [ 20.839658] param_attr_store+0xbc/0x150 [ 20.839920] module_attr_store+0x40/0x58 [ 20.840183] sysfs_kf_write+0x8c/0xa8 [ 20.840183] sysfs_kf_write+0x8c/0xa8 [ 20.840440] kernfs_fop_write+0x154/0x290 [ 20.840702] vfs_write+0xf0/0x278 [ 20.840942] __arm64_sys_write+0x84/0xf4 [ 20.841209] el0_svc_common+0xf4/0x1dc [ 20.841471] el0_svc_handler+0x98/0xbc [ 20.841713] el0_svc+0x8/0xc [ 20.842057] Code: bad PC value [ 20.842764] ---[ end trace a8835d7de79aaadf ]--- [ 20.843134] Kernel panic - not syncing: Fatal exception [ 20.843515] SMP: stopping secondary CPUs [ 20.844289] Kernel Offset: disabled [ 20.844634] CPU features: 0x0,21806002 [ 20.844857] Memory Limit: none [ 20.845172] ---[ end Kernel panic - not syncing: Fatal exception ]--- Signed-off-by: Miles Chen Signed-off-by: Greg Kroah-Hartman Signed-off-by: Sasha Levin --- drivers/tty/tty_io.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/tty/tty_io.c b/drivers/tty/tty_io.c index e6429d419b80..e6c4321d695c 100644 --- a/drivers/tty/tty_io.c +++ b/drivers/tty/tty_io.c @@ -354,7 +354,7 @@ struct tty_driver *tty_find_polling_driver(char *name, int *line) mutex_lock(&tty_mutex); /* Search through the tty devices to look for a match */ list_for_each_entry(p, &tty_drivers, tty_drivers) { - if (strncmp(name, p->name, len) != 0) + if (!len || strncmp(name, p->name, len) != 0) continue; stp = str; if (*stp == ',') -- 2.17.1