From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from out-189.mta0.migadu.com (out-189.mta0.migadu.com [91.218.175.189]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id A0CEF262FFC for ; Thu, 28 Aug 2025 13:01:39 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=91.218.175.189 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1756386101; cv=none; b=EsnKftAg4yDq/uOZlYsivJB1jClDWNtZCMQWwWt1/LWNJt8mEuVCh65K0ddpe7MvGrjNVLiaMie3LfMLQMi3WFQnQBumWe4GIcrDun3Cs7rXdZbikEx/47tKvSWFQ7HghmZFrUU3hayltVaDxl997AZyBYSTbG1S6tTHFTkaGAc= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1756386101; c=relaxed/simple; bh=YR/qZ84vLiQKuz+/Sxg5SyMSGAAAoTDdsnFm77awHyE=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=CUsz16MqZS+dd6TLtrUf0ud6MBKHVwynvmyD27yAKW2kdr4Fi0N8MfH8/LE+XTY3Y0FCfBg6bqcTYaDYeU8Cmgk9zt7QIDcBezZlJCuq1Lz3Gi93PjX0/d+bCkBppuZHgl35CTRNdA2PaLj+eigMnHa2z41tLManV/Ig7uV2N8U= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev; spf=pass smtp.mailfrom=linux.dev; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b=ra8FPJf0; arc=none smtp.client-ip=91.218.175.189 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.dev Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b="ra8FPJf0" Message-ID: DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1756386087; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=P7v68eUbMhdBb1FN26U9K+vJv5tGLAeNVJMhgqgmwlM=; b=ra8FPJf02ezT/Z6Od+0hGN4l4CJBp5cRRQwc7kivX348XlYc76qHJiTCY2Zbr6BzuhziWV vtp6ovLknz+EW3nWC8g/Y5koIGMS61GWL+j18xx61d5DIBaIiGVrOdIF2zednYc5wZw2gS Hu5qlNzC2MneYgUfwtN/+OFL0BuZwcQ= Date: Thu, 28 Aug 2025 14:01:23 +0100 Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Subject: Re: [PATCH] net: ethernet: ti: Prevent divide-by-zero in cpts_calc_mult_shift() To: =?UTF-8?B?5p6X5aaZ5YCp?= Cc: Andrew Lunn , "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Matthias Brugger , AngeloGioacchino Del Regno , Thomas Gleixner , Grygorii Strashko , netdev@vger.kernel.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-mediatek@lists.infradead.org References: <20250828092224.46761-1-linmq006@gmail.com> <11d46e56-b8d9-4776-9969-d3767d8cda41@linux.dev> Content-Language: en-US X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. From: Vadim Fedorenko In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-Migadu-Flow: FLOW_OUT On 28/08/2025 13:38, æå¦å© wrote: > Hi, Vadim > > Vadim Fedorenko 于2025年8月28日周四 20:06写道： >> >> On 28/08/2025 10:22, Miaoqian Lin wrote: >>> cpts_calc_mult_shift() has a potential divide-by-zero in this line: >>> >>> do_div(maxsec, freq); >>> >>> due to the fact that clk_get_rate() can return zero in certain error >>> conditions. >> >> Have you seen this happening in the real environment, or is it just >> analysis of the code? I don't see a reason for these "certain error >> conditions" to happen... > > This is from code analysis, not from real environment. > The !CONFIG_HAVE_CLK version of clk_get_rate() returns zero. > With CONFIG_COMPILE_TEST && !CONFIG_HAVE_CLK could have the problem. > This may be theoretical. !CONFIG_HAVE_CLK will have cpts_create() doing nothing as defined in cpts.h and it means the patch fixes impossible scenario. NAck