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=-7.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS autolearn=no 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 53B5BC433DB for ; Wed, 13 Jan 2021 05:06:10 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id BDEC32310F for ; Wed, 13 Jan 2021 05:06:09 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1725977AbhAMFFx (ORCPT ); Wed, 13 Jan 2021 00:05:53 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:57082 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725818AbhAMFFw (ORCPT ); Wed, 13 Jan 2021 00:05:52 -0500 Received: from mail-yb1-xb29.google.com (mail-yb1-xb29.google.com [IPv6:2607:f8b0:4864:20::b29]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 2F542C061794; Tue, 12 Jan 2021 21:05:12 -0800 (PST) Received: by mail-yb1-xb29.google.com with SMTP id g4so985947ybo.11; Tue, 12 Jan 2021 21:05:12 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:from:date:message-id:subject:to; bh=H2fJ/axecH/6J+gsobPUGUVGWusfX311kFU3BlwJyaw=; b=WdUKppHh5qE2nA/G2cqUSZgTE18MWaSdNoakRvX046FhmCZ7Ouqhy11j5jqFhEsx7+ ZrJk5+BKCXJuiT0CjYMC7Clj/gilwyFxQUF5WR2k2YiShWhoHSF4i2q0s7JZ568PojuG PgpVcLcPz9GuBSwWEZecqTVUrWWJpW7fx+pw9DJ0pbhQ1Glj9XEiztH/3Iq66SUQjT4X /shzjl/k74NjNNj/SmsXNmQo0yKfdlbeGsIBXm1S7ypGtWq5lLiojgwkF/ImqvfwWHpL IchiUjjal3JJ3/GF5ArYvNdyu+7Wb3MzPs3/Y+uQ5l+/lZT67nnyBwWTB0Wv/jigNqqv A3iw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:from:date:message-id:subject:to; bh=H2fJ/axecH/6J+gsobPUGUVGWusfX311kFU3BlwJyaw=; b=OBVFB2KPBb5BOvfG08lVC/eIlYOZHKuSlVgVOio9OKYwV222sARp+JkC09RZU5cb2G WqB9C/BBPG8nPA8LJRzdGbth9iQtTFTGxvL/y4bvdgMtOWpqWmfilgABiourov58f4uK HzQXeu9ACjFbfgTswIM0QGm37/KAJKchXVQVi2W8Bto/N/+SgQlnSYx3bMsnV9+7ndlQ YpDVghmOJxG47iM+U+hAxlxtJtHRroXhN8uvvhUnGRqTVfX6T03FRCg93cfaZlWUphiA YDO43PEk47wH03moS9cPwqlTKJjwnoUf2gtKkPt+dFn4wVlUBt3FY35Pr6k3xOTuaP8A SrSg== X-Gm-Message-State: AOAM5307ZAjKLsfmCxV2AirKkuqfZvpukwhI68ovj0fZZAl4egcC0UBU RiOmrCC3HK0ZLDraocQt57Y/3g/Ehmxvi+IU3/FqUU9JpCfvhrnr X-Google-Smtp-Source: ABdhPJwWR5KSECnDvOvXv6NvLQlRekb3+GXlW2S+NzrNMmuR5ehuW0T0YGRFcXu/k0xODwLSL3lxja4jF5Sj55pjyfU= X-Received: by 2002:a25:3457:: with SMTP id b84mr796341yba.167.1610514311118; Tue, 12 Jan 2021 21:05:11 -0800 (PST) MIME-Version: 1.0 From: =?UTF-8?B?5oWV5Yas5Lqu?= Date: Wed, 13 Jan 2021 13:04:44 +0800 Message-ID: Subject: "UBSAN: shift-out-of-bounds in mceusb_dev_recv" should share the same root cause with "UBSAN: shift-out-of-bounds in mceusb_dev_printdata" To: linux-kernel , linux-media@vger.kernel.org, mchehab@kernel.org, sean@mess.org, anant.thazhemadam@gmail.com, syzkaller-bugs , Greg KH , Dmitry Vyukov Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi developers, I found that "UBSAN: shift-out-of-bounds in mceusb_dev_recv" and "UBSAN: shift-out-of-bounds in mceusb_dev_printdata" should share the same root cause. The reason is that the PoCs after minimization has a high similarity with the other. And their stack trace only diverges at the last function call. The following is some analysis for this bug. The following code in the mceusb_process_ir_data is the vulnerable -------------------------------------------------------------------------------------------------------------------------- for (; i < buf_len; i++) { switch (ir->parser_state) { case SUBCMD: ir->rem = mceusb_cmd_datasize(ir->cmd, ir->buf_in[i]); mceusb_dev_printdata(ir, ir->buf_in, buf_len, i - 1, ir->rem + 2, false); if (i + ir->rem < buf_len) mceusb_handle_command(ir, &ir->buf_in[i - 1]); -------------------------------------------------------------------------------------------------------------------------- The first report crashes at a shift operation(1<<*hi) in mceusb_handle_command. -------------------------------------------------------------------------------------------------------------------------- static void mceusb_handle_command(struct mceusb_dev *ir, u8 *buf_in) { u8 *hi = &buf_in[2]; /* read only when required */ if (cmd == MCE_CMD_PORT_SYS) { switch (subcmd) { case MCE_RSP_GETPORTSTATUS: if (buf_in[5] == 0) ir->txports_cabled |= 1 << *hi; -------------------------------------------------------------------------------------------------------------------------- The second report crashes at another shift operation (1U << data[0]) in mceusb_dev_printdata. -------------------------------------------------------------------------------------------------------------------------- static void mceusb_dev_printdata(struct mceusb_dev *ir, u8 *buf, int buf_len, int offset, int len, bool out) { data = &buf[offset] + 2; period = DIV_ROUND_CLOSEST((1U << data[0] * 2) * (data[1] + 1), 10); -------------------------------------------------------------------------------------------------------------------------- >From the analysis, we can know the data[0] and *hi access the same memory cell - ``ir->buf_in[i+1]``. So the root cause should be that it misses the check of ir->buf_in[i+1]. For the patch of this bug, there is one from anant.thazhemadam@gmail.com: -------------------------------------------------------------------------------------------------------------------------- diff --git a/drivers/media/rc/mceusb.c b/drivers/media/rc/mceusb.c index f1dbd059ed08..79de721b1c4a 100644 --- a/drivers/media/rc/mceusb.c +++ b/drivers/media/rc/mceusb.c @@ -1169,7 +1169,7 @@ static void mceusb_handle_command(struct mceusb_dev *ir, u8 *buf_in) switch (subcmd) { /* the one and only 5-byte return value command */ case MCE_RSP_GETPORTSTATUS: - if (buf_in[5] == 0) + if ((buf_in[5] == 0) && (*hi <= 32)) ir->txports_cabled |= 1 << *hi; break; -------------------------------------------------------------------------------------------------------------------------- I tried this patch in the second crash report and found it does not work. I think we should add another filter for the value in ``ir->buf_in[i+1]``. With this grouping, I think developers can take into consideration the issue in mceusb_dev_printdata and generate a complete patch for this bug. If any of my understanding is incorrect or has issues, please let me know. Thanks very much. -- My best regards to you. No System Is Safe! Dongliang Mu