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 Received: from gabe.freedesktop.org (gabe.freedesktop.org [131.252.210.177]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 6469DCD5BD1 for ; Thu, 28 May 2026 06:18:41 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 8223010EC7E; Thu, 28 May 2026 06:18:40 +0000 (UTC) Authentication-Results: gabe.freedesktop.org; dkim=pass (2048-bit key; unprotected) header.d=gmail.com header.i=@gmail.com header.b="STHUmUR4"; dkim-atps=neutral Received: from mail-wr1-f51.google.com (mail-wr1-f51.google.com [209.85.221.51]) by gabe.freedesktop.org (Postfix) with ESMTPS id 9764D10EC7E for ; Thu, 28 May 2026 06:18:39 +0000 (UTC) Received: by mail-wr1-f51.google.com with SMTP id ffacd0b85a97d-43d76dd4ee8so7627043f8f.2 for ; Wed, 27 May 2026 23:18:39 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20251104; t=1779949118; x=1780553918; darn=lists.freedesktop.org; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:from:to:cc:subject:date:message-id:reply-to; bh=eDowC+J9NkAkNKGl2xFdM++bofz3BCUgA7OJQhuHtSY=; b=STHUmUR4PX3Axl4WAbmu85E/NE00MOj5kcCqbBeihkcVTW4iCj0UmnphwSDtXI8lLF X7byE5GIswmvE1p7f7jCrVEyTGUKX2wMh9NA6DQICP/X5/rLh046KPOG2as+lKN+1Q6N Guk9aaeZe85McaVej9LEjw1U0ZSd2KG2DWhnyGZ0Q9ufIQCDqceaO9z7JaZTwyfnEJUr bHeMG07KgG9ogXJ9DCcab0mmFgRvnETIYL9JH3GGCIb922q9xLrEiE715BGceys0ybso SXTa2RJyPe5nCaPAl660en384vwpndxeWXYsIFB+5a8Q4+W5/FSwTD1yosBETfb4qxoL HBlw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1779949118; x=1780553918; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:x-gm-gg:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=eDowC+J9NkAkNKGl2xFdM++bofz3BCUgA7OJQhuHtSY=; b=QICbHeiOw0NWVnv0nVyVhYWv3Apvzh/DoH+dO8h4keLwc3UqBWpsP8ODDDqxrQGHuI To9Sw0ix3XrEMKnhN7MtnuOt9Dl2HiYMp/5C/lWeF/SpG9EXcXG25qo1tXviODFRtKCw sKKRIvREVMdssISDCqu6GZvWlpD0go+M61ab1cxLfRV8XUDZBk1LhgkamCrFcnKWAvLq ga+suQm2DmM4TjLqummW24tP8+3TunkpXfCPM8W9XBlJjT7/jH9LPvJm30s9LE3JrXrn avef/+TZm1OzX0jCrQHn5dzuBL6xQWBT9hOOzMnyuSYipE4tmIFYrmpGlF+YmJK5NSKH Vhmw== X-Forwarded-Encrypted: i=1; AFNElJ8PjWlfVMb0Tg4+DXUGbbkVHhaUcRkWASsfpxsKqsdLNv+PwsAXrkaFSKgqcoVv3vk9DKiBE04K648=@lists.freedesktop.org X-Gm-Message-State: AOJu0YyLMnpfFE7fM61y8ngLRifYbavdDAXNlB8l2CHI/z0GhnVYN/4D 0joOdddkCwWC03Oy5FSST4vW3NCCle9KcAarMDlsh0vJNzrFosWspjFF X-Gm-Gg: Acq92OEBspB9fykMWrCmg9pFIkr8tvAHZuO+7ti1yegAbee8kefJ0OWxa+zyPaGpA/X 5yLeiW44XZRJfUu7HNdlRNGHUVVPQhvZ56xew4WJtSvB2JGNOsv5E4pePtzXOuLIr+U5BrinnGu ohL3+pMh2/Vazkv5dnLi9m7NRLY8A7o6uGj8mtLFIDQuftkzrvkbHALBn5SjiaRBvklblpCpbpW l1EXVnuOcjz2T4MalHIlkQlmea6uQqUooILUCxci5RvYRgB1HJBjwUffTIDxrFAtuq1AMwRdrzb +e7chPAipr6hkE+vrBoSt+c6Lg+F8a92VvffH/QDE5Yquy9CW1egEt6SGvJWdqxgtT7PgaCDClL ikgUY6p+q4WSvkQ42qs9bEiqRdSKSsgmL1ExVn7KCF089jCzB0Reb1kFkZI47l5YIzg/jCPSv5u 9zDbth+B9a4KrzrhUg/vXmmW0SsLjwoLyUkA== X-Received: by 2002:a05:6000:480f:b0:43f:e43a:f4a6 with SMTP id ffacd0b85a97d-45eb3691f71mr43798818f8f.6.1779949118000; Wed, 27 May 2026 23:18:38 -0700 (PDT) Received: from localhost ([196.207.164.177]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-45edb5a281dsm10925489f8f.24.2026.05.27.23.18.36 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 27 May 2026 23:18:37 -0700 (PDT) Date: Thu, 28 May 2026 09:18:34 +0300 From: Dan Carpenter To: Sean Anderson Cc: Laurent Pinchart , Tomi Valkeinen , Maarten Lankhorst , Maxime Ripard , Thomas Zimmermann , David Airlie , Simona Vetter , Michal Simek , dri-devel@lists.freedesktop.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, kernel-janitors@vger.kernel.org Subject: Re: [PATCH] drm: zynqmp_dp: Fix uninitialized variable in debugfs() Message-ID: References: <935aaec5-5417-3cde-f944-3c04ffbd3458@linux.dev> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <935aaec5-5417-3cde-f944-3c04ffbd3458@linux.dev> X-BeenThere: dri-devel@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Direct Rendering Infrastructure - Development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" On Wed, May 27, 2026 at 08:31:59PM -0400, Sean Anderson wrote: > On 5/25/26 03:16, Dan Carpenter wrote: > > If the *ppos is non-zero then simple_write_to_buffer() will not > > initialize the start of the buf[] buffer. It doesn't really make sense > > to allow non-zero values for *ppos, so check for that at the start and > > return -EINVAL. > > non-zero ppos seems to be handled properly by simple_write_to_buffer. > It's not an overflow bug, it's an uninitialized variable bug. The simple_write_to_buffer() is designed to handle partial writes so it leaves the first "written" (scare quotes) part of the string as is. But in this case, we can't handle a partial write and the first part of buf[] is left uninitialized. https://staticthinking.wordpress.com/2026/05/23/simple_write_to_buffer-is-complicated/ Also this appears to be dead code since fops_zynqmp_dp_pattern is never used. regards, dan carpenter