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=-4.2 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_SANE_1 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 83B6CC4338F for ; Thu, 12 Aug 2021 04:21:42 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 6145B60EFE for ; Thu, 12 Aug 2021 04:21:42 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233333AbhHLEWD (ORCPT ); Thu, 12 Aug 2021 00:22:03 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:49854 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229531AbhHLEWC (ORCPT ); Thu, 12 Aug 2021 00:22:02 -0400 Received: from mail-pl1-x62a.google.com (mail-pl1-x62a.google.com [IPv6:2607:f8b0:4864:20::62a]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 7076DC061765; Wed, 11 Aug 2021 21:21:38 -0700 (PDT) Received: by mail-pl1-x62a.google.com with SMTP id c17so282290plz.2; Wed, 11 Aug 2021 21:21:38 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=to:cc:from:subject:message-id:date:user-agent:mime-version :content-transfer-encoding:content-language; bh=rzIfPgU+iHWBSpnuOzwI+tb+zgZVbNg5XJGowiab0uM=; b=hE+kDUUwVW0gsA5brzQZUsFwxGyhKekgHRx+YYEq4sQ2FJC7S3M3vYmI8hc7RcHdK9 xGoBfdHwLJEII6vW6leXG3Y7/L59mnLol4Q2bXJysBvda6ULoV513c91reejQ4Qn0urF QxFTm9QW2nZTR+3TQGbzx9ZG4RPEBocGPpE1Z/InOfUn6Axa/GUG/QNX+1vMs3cJn3OB Ouwr8aJttioX87ktD0hj25eQAzaRTx8V3hpKBEbX17Q03aAcnC4i8J9BCnCQMe/vyFXc 6uti4gnxEqc/fIRcv7/dYdYhPgfCCe+wkXgElOj4MshqaT4D6F1AXFgoVjgcwzF1qN1J yDYA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:to:cc:from:subject:message-id:date:user-agent :mime-version:content-transfer-encoding:content-language; bh=rzIfPgU+iHWBSpnuOzwI+tb+zgZVbNg5XJGowiab0uM=; b=rPAnCnWxE/iFsrFOu9ag0xV1fQLA6LQsgwEuFtL4OEbFBqvG4ACH21uoYO3H/B9sBf jSXZrjbP2uPY8mdIHIjH57RlIK8psrOhtNrscJ77XeGPq33fll71bSt7oa6iNCZy3d4X 4thaR5pwEaHka89Efvn8E3jtZFfaOMHrS6t85tEMTfO0GKbFcIQjJOQXtYCVhzCiyj1J FwY8vPmh400GfX54D8enB4RHQiCtb0KYugPF88rmLPvOTobkpjN/6kpKYEya/x69cXki bFv5Mgh3NNMCFqi21x0AGabit8inratxeMQZXoCvHcMz/Nq9WOICENDvYoTsX5FwCgyK TRaQ== X-Gm-Message-State: AOAM530fDCfN+heyICtZl73yfBmh7xcVvG7uPI8v+Tie4JwdPoNI2j3v chjHsTIWLR9e1bU7HR5aheY= X-Google-Smtp-Source: ABdhPJxRBqxoMId4E22yz1C+ubk21gLJ7FJsKhaOWBIvDxbrkcCmcET5eghsTtM+F5ffIVyfP23y/g== X-Received: by 2002:a65:6454:: with SMTP id s20mr2082856pgv.18.1628742098033; Wed, 11 Aug 2021 21:21:38 -0700 (PDT) Received: from [10.157.0.26] ([85.203.23.10]) by smtp.gmail.com with ESMTPSA id g19sm8440629pjl.25.2021.08.11.21.21.35 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 11 Aug 2021 21:21:37 -0700 (PDT) To: mchehab@kernel.org, hverkuil-cisco@xs4all.nl, christophe.jaillet@wanadoo.fr, tglx@linutronix.de Cc: linux-media@vger.kernel.org, Linux Kernel , "baijiaju1990@gmail.com" From: Tuo Li Subject: [media] cx25821: Is there a potential buffer-underflow in cx25821-core.c? Message-ID: <22f3bdcb-dc29-b6a7-941e-6218f0a8791d@gmail.com> Date: Thu, 12 Aug 2021 12:21:35 +0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:78.0) Gecko/20100101 Thunderbird/78.13.0 MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 8bit Content-Language: en-US Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hello, Our static analysis tool reports a possible buffer-underflow in cx25821-core.c in Linux 5.14.0-rc3: The variable channel_select is checked in: 761:    if (channel_select <= 7 && channel_select >= 0) This indicates that channel_select can be negative. If so, a buffer-underflow will occur: 765:    dev->channels[channel_select].pixel_formats = format; However, we checked this report manually, and found that the only call site is in cx25821-video.c: 394:    cx25821_set_pixel_format(dev, SRAM_CH00, pix_format); And SRAM_CH00 is not negative. I am not sure whether this negatvie-check is redundant or there is a potential buffer-underflow. Any feedback would be appreciated, thanks! Reported-by: TOTE Robot Best wishes, Tuo Li