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=-6.6 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,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 089EAC433E0 for ; Mon, 25 May 2020 23:27:45 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id D3E962071A for ; Mon, 25 May 2020 23:27:44 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="YnNW/doW" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729016AbgEYX1o (ORCPT ); Mon, 25 May 2020 19:27:44 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:46950 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726408AbgEYX1n (ORCPT ); Mon, 25 May 2020 19:27:43 -0400 Received: from mail-pl1-x641.google.com (mail-pl1-x641.google.com [IPv6:2607:f8b0:4864:20::641]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 6398DC061A0E for ; Mon, 25 May 2020 16:27:43 -0700 (PDT) Received: by mail-pl1-x641.google.com with SMTP id k22so7916316pls.10 for ; Mon, 25 May 2020 16:27:43 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=date:from:to:cc:subject:message-id:mime-version:content-disposition; bh=YztR7HplbxQ7LgSZiF2gBF8J+ZDPdJj2iwdzAUHkXHE=; b=YnNW/doWLujhEydk8v0KvCVsf+LdytAaMcEaXtBFuaPRvTWr+gCrtNWWJstF3lP5Fr lh9K4N/kbzcjTLu/qgyaIODEKy9zFEVeqVew7ApNTYFB3eHrvRE6SJHg1PrLz6oYDTt9 rlo4g3qAd/PJUs3IsoSHvtep5Mx6LJBnpio39kUxSA5C9u/CrsjtJYBURuYSwRqslrIi 9nPraIqOhLiGGohW4Y+VUztPDGcvWQoZnn2CvWCzYnHo0xGZxl3/pSx2UEnuUqgwJgoh rkbgyH4AABJNnYApGIbmi3d11El4HNAdrepYyWVAN4lwEBlTOvRiyyN4/elwrCNm9hb7 lB3Q== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:mime-version :content-disposition; bh=YztR7HplbxQ7LgSZiF2gBF8J+ZDPdJj2iwdzAUHkXHE=; b=lpmiUAXOQGnkNchQc749wadEI5nrMbvre5AuNnaJYDNXgVXa2ZRvixEXMx3Si9xfmj vkPgu/1pj73LsAtUsFbYhrccbU5IbEEmaSXxlN4fGiROIRoHGPGaSlPQ+VpsL2czyUvj WhUFm9ZnwZYOfsL4obgLQhvD5pd4INCkGXiBFLOKhb/yj28s1Uuwgu1FcnKkinc4MoO8 DEM6np0Rn5uyw/9mR9f7cJ7BKiygJi4LzLksVUr7K28awR+sVlPqWXwu7mMWu3+mOBCN q9LEzEhe7HoAALX8KLqI7gFSlhN0hn+TqPLuW/5/PUvZQFXVN5tUorrbE2/AeAtC97Sw WHGQ== X-Gm-Message-State: AOAM531vrdlEM3zqQRdPP74jwbuacyq/gTjaHtwPpPx0RZDUxL+5X3am q6q0Qt/yzf9iy2QnDY0qE0U= X-Google-Smtp-Source: ABdhPJzdk4UHRfMeaRg1LafDe/aiawXLaGPJQKCHj17G5Am/PSgTZbJ9/URNacXc6L2BhSWT02fd4A== X-Received: by 2002:a17:902:fe04:: with SMTP id g4mr30225518plj.327.1590449262731; Mon, 25 May 2020 16:27:42 -0700 (PDT) Received: from dtor-ws ([2620:15c:202:201:3c2a:73a9:c2cf:7f45]) by smtp.gmail.com with ESMTPSA id l10sm13815985pfd.70.2020.05.25.16.27.42 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 25 May 2020 16:27:42 -0700 (PDT) Date: Mon, 25 May 2020 16:27:40 -0700 From: Dmitry Torokhov To: Greg Kroah-Hartman Cc: Jiri Slaby , linux-kernel@vger.kernel.org Subject: [PATCH v3] vt: keyboard: avoid signed integer overflow in k_ascii Message-ID: <20200525232740.GA262061@dtor-ws> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org When k_ascii is invoked several times in a row there is a potential for signed integer overflow: UBSAN: Undefined behaviour in drivers/tty/vt/keyboard.c:888:19 signed integer overflow: 10 * 1111111111 cannot be represented in type 'int' CPU: 0 PID: 0 Comm: swapper/0 Not tainted 5.6.11 #1 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:77 [inline] dump_stack+0xce/0x128 lib/dump_stack.c:118 ubsan_epilogue+0xe/0x30 lib/ubsan.c:154 handle_overflow+0xdc/0xf0 lib/ubsan.c:184 __ubsan_handle_mul_overflow+0x2a/0x40 lib/ubsan.c:205 k_ascii+0xbf/0xd0 drivers/tty/vt/keyboard.c:888 kbd_keycode drivers/tty/vt/keyboard.c:1477 [inline] kbd_event+0x888/0x3be0 drivers/tty/vt/keyboard.c:1495 While it can be worked around by using check_mul_overflow()/ check_add_overflow(), it is better to introduce a separate flag to signal that number pad is being used to compose a symbol, and change type of the accumulator from signed to unsigned, thus avoiding undefined behavior when it overflows. Reported-by: Kyungtae Kim Signed-off-by: Dmitry Torokhov --- - marking the patch as v3 as it is a successor of Kyungtae's patches. drivers/tty/vt/keyboard.c | 26 ++++++++++++++++---------- 1 file changed, 16 insertions(+), 10 deletions(-) diff --git a/drivers/tty/vt/keyboard.c b/drivers/tty/vt/keyboard.c index 15d33fa0c925..568b2171f335 100644 --- a/drivers/tty/vt/keyboard.c +++ b/drivers/tty/vt/keyboard.c @@ -127,7 +127,11 @@ static DEFINE_SPINLOCK(func_buf_lock); /* guard 'func_buf' and friends */ static unsigned long key_down[BITS_TO_LONGS(KEY_CNT)]; /* keyboard key bitmap */ static unsigned char shift_down[NR_SHIFT]; /* shift state counters.. */ static bool dead_key_next; -static int npadch = -1; /* -1 or number assembled on pad */ + +/* Handles a number being assembled on the number pad */ +static bool npadch_active; +static unsigned int npadch_value; + static unsigned int diacr; static char rep; /* flag telling character repeat */ @@ -845,12 +849,12 @@ static void k_shift(struct vc_data *vc, unsigned char value, char up_flag) shift_state &= ~(1 << value); /* kludge */ - if (up_flag && shift_state != old_state && npadch != -1) { + if (up_flag && shift_state != old_state && npadch_active) { if (kbd->kbdmode == VC_UNICODE) - to_utf8(vc, npadch); + to_utf8(vc, npadch_value); else - put_queue(vc, npadch & 0xff); - npadch = -1; + put_queue(vc, npadch_value & 0xff); + npadch_active = false; } } @@ -868,7 +872,7 @@ static void k_meta(struct vc_data *vc, unsigned char value, char up_flag) static void k_ascii(struct vc_data *vc, unsigned char value, char up_flag) { - int base; + unsigned int base; if (up_flag) return; @@ -882,10 +886,12 @@ static void k_ascii(struct vc_data *vc, unsigned char value, char up_flag) base = 16; } - if (npadch == -1) - npadch = value; - else - npadch = npadch * base + value; + if (!npadch_active) { + npadch_value = 0; + npadch_active = true; + } + + npadch_value = npadch_value * base + value; } static void k_lock(struct vc_data *vc, unsigned char value, char up_flag) -- 2.27.0.rc0.183.gde8f92d652-goog -- Dmitry