From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-lf1-f54.google.com (mail-lf1-f54.google.com [209.85.167.54]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 20279156875; Mon, 7 Oct 2024 10:00:50 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.167.54 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1728295253; cv=none; b=CxGf5SqNtO4DWsHg38USDihz3Ds9KAGeG0P2GuRnE0vlb8UL8G6xK9kJeYcobFcBZzBShUwUKual0oD+uzgflDepJV/4zhYexcj0oKrMlx57t1jDKf0iZIw3yn/VijzVLGMJX22n77OwZsMgBBML3gd+uYlI4wnOlaMQ0vHFn3E= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1728295253; c=relaxed/simple; bh=8jLkDLa1KjvLII9dGVbKrzkDwrGVZgRVLaCZdg+1BGI=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=oN6YHK+9MrPTfQQB8H+k2qMCtBFFOId9SIgNaVEITqUGyqd8pajKFf9aGbXL2TQ8SF+dC3rM3JpCjX4hUVLTRX8Awfakph+a1OWWWWtQu5s4k26KD4nAzQvXf5ovyBSxn7LyFNBfGTXSzVmOuC/pbINRceoE9Jrn+eKSVEvGjnM= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com; spf=pass smtp.mailfrom=gmail.com; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b=WYiQ1XET; arc=none smtp.client-ip=209.85.167.54 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=gmail.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="WYiQ1XET" Received: by mail-lf1-f54.google.com with SMTP id 2adb3069b0e04-53992157528so4401664e87.2; Mon, 07 Oct 2024 03:00:50 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20230601; t=1728295249; x=1728900049; darn=vger.kernel.org; h=content-transfer-encoding:in-reply-to:from:content-language :references:cc:to:subject:user-agent:mime-version:date:message-id :from:to:cc:subject:date:message-id:reply-to; bh=+6HLACYIYStp6InlFY/UrXlQ9BZcSDR4bw3DCXtnczc=; b=WYiQ1XET1GlM64YwKbZpRd+Hw9J8M8CedHOvQl3E7Q1A+3WfKJDmCX3L5n1Ea1vSCY KVmEPcbUA1p9pcKwkom4/rG4Qmx4UcoMzmsKKhfzfFHRmeZDUjgRmJ/vN/C5NR//zonY P1PjkYxI0fFM1+fVcHDBlbgbJAVzRoNXCiOolwCIYUzjROFnrzkjeKp4sYnf0gprKeCC tWKHhDFA8Vm2Y30rC6fS5fauEnnilkHAQGL1S5kt0KGQGx/ZBL+XV8Q9nm5/t7QEm+rX gcyWnu/rVtdMChAP7VPQu40BGWi3453owggUeBhXakDspQ7YzrZfbHh027JxtIF8wS6G oIZQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1728295249; x=1728900049; h=content-transfer-encoding:in-reply-to:from:content-language :references:cc:to:subject:user-agent:mime-version:date:message-id :x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=+6HLACYIYStp6InlFY/UrXlQ9BZcSDR4bw3DCXtnczc=; b=UahCVPPXaHEq4bpWEqRssliRmWI+fGFuWpHU6OlQ2FgGtsNkZaYMXsSW3gqBtMC7fa efsMHW0yRbJBX45kAV4IwWQgFYyXR3IYcvi2z9o+Ok805M195JQSx8HNeIbGBD2FSjz6 UrJsp1VITHqWKps11fr8YUq+ja0l9ygF09ePIhAtWFx9P4VIzbMEKR948/ZTbn3AND++ 7Irk+41xGgIjDRL0iSt1a1uWKnLsKohhOlJEfaQCRqUy1kp/yMdcp+7xU3BGgRwZjEu3 JjvQc+UndaFzXVSjeG0QBDms9xKEQnKzLlvkP0eHfQaqqYURKs80NgvDgW4x7qX4mDtC nJyQ== X-Forwarded-Encrypted: i=1; AJvYcCVWeOTwKfJrWVf9ZAlRbVLUGRkgQh3tbyxOfgCdK8pk5gHhFEjvcNmczSoomQDrwscTgKQ5Hu1U7W17j+EI@vger.kernel.org, AJvYcCWJ1S8051DWYPlLAh+7NhsCQoDSiF9k6PyMAdvmN1NJRz57e/rt3e0Gubmw1TrWg5iHR8bLZ6b46k26@vger.kernel.org, AJvYcCXP1GPZ1C7uKaqEQ48BS3UiMlp3OFt318roQPe0bevHhz9BFNEo/3maPHJbaZRUtH3Y5hurhS62KQKeOnhpxcw=@vger.kernel.org X-Gm-Message-State: AOJu0YzGbNZnp7eEdJV9AIOExDo//78iyEHhwRDyHFPRPUM5w16nTLdC rEZqZSCb5SuHg6gYZaq0HkQJqHsN7dxXdmcM94FRz1GZvjhN1gyD X-Google-Smtp-Source: AGHT+IE7fzKBCyOHsn6sB/8KjqsNw34RTIfeHeJEYQWXt64wGo1SEdrFPzcHNdDA5aHtq/+F5n0h3g== X-Received: by 2002:a05:6512:12ca:b0:538:9b5d:9885 with SMTP id 2adb3069b0e04-539ab6d851emr5214374e87.0.1728295248943; Mon, 07 Oct 2024 03:00:48 -0700 (PDT) Received: from [192.168.0.101] (craw-09-b2-v4wan-169726-cust2117.vm24.cable.virginm.net. [92.238.24.70]) by smtp.googlemail.com with ESMTPSA id a640c23a62f3a-a9957d955f8sm99206066b.74.2024.10.07.03.00.47 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 07 Oct 2024 03:00:48 -0700 (PDT) Message-ID: <6181060a-ae36-4d0f-bfe0-c1e5c8a8ab3c@gmail.com> Date: Mon, 7 Oct 2024 11:00:46 +0100 Precedence: bulk X-Mailing-List: linux-clk@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH][next] clk: imx: pll14xx: Fix potential integer overflow on multiplication To: Dan Carpenter Cc: Abel Vesa , Peng Fan , Michael Turquette , Stephen Boyd , Shawn Guo , Sascha Hauer , Pengutronix Kernel Team , Fabio Estevam , linux-clk@vger.kernel.org, imx@lists.linux.dev, linux-arm-kernel@lists.infradead.org, kernel-janitors@vger.kernel.org, linux-kernel@vger.kernel.org References: <20241007084840.1167527-1-colin.i.king@gmail.com> <3e0def9f-ebb6-4171-9395-1da118b0ea29@stanley.mountain> Content-Language: en-US From: "Colin King (gmail)" In-Reply-To: <3e0def9f-ebb6-4171-9395-1da118b0ea29@stanley.mountain> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 07/10/2024 10:54, Dan Carpenter wrote: > On Mon, Oct 07, 2024 at 09:48:40AM +0100, Colin Ian King wrote: >> The calculation of fout is using int multiplication and assigning >> the result to a u64, this can potentially overflow if the int variable >> mdiv is too large. Fix this by making the 65536 a u64 value to ensure a >> u64 multiplication is being performed to avoid the overflow. >> >> Fixes: 53990cf9d5b4 ("clk: imx: pll14xx: consolidate rate calculation") >> Signed-off-by: Colin Ian King > > mdiv is always clamped in then 0-1023 range by one of these: > > mdiv = FIELD_GET(MDIV_MASK, pll_div_ctl0); > mdiv = clamp(mdiv, 64, 1023); > > so it can't overflow and the Fixes tag is unnecessary. Good point. > > I think the reason why "fout" is declared as a u64 is because we were worried > that on 32 bit systems the "fout *=" operation could overflow. That looks > reasonable to me. Yes, that makes perfect sense. NAK my patch. Apologies for the noise. Colin > > regards, > dan carpenter >