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 bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (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 3F870C0218C for ; Wed, 22 Jan 2025 22:59:41 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:Content-Transfer-Encoding: Content-Type:MIME-Version:References:In-Reply-To:Message-ID:Subject:Cc:To: From:Date:Reply-To:Content-ID:Content-Description:Resent-Date:Resent-From: Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=jqVF0cBTijRuq0m7GTGEM8FFP9eJBtgNqw9jRV9T5lo=; b=Hb7AIsvx6Q6GpQcl+KMrsDTFMZ J5vKSE3HW20PhJGfVskrcnWAL37VFB9u9AnZalhUXWqyqMIQ2ol6QYxQgURNm5GNYt58zQFjr9Vjv V7V0nyPyxe2U9W/jKWTLamkLFxeC6DQ7ztKleCjpAOVfPZm3s0aLsj7WkLYQDwXt8P/gWvjTuadMX ItY50VsOuZT6+CjpmAs56J2+4y7kHCOxQcu1U7a0cZDGeTy0Qp1dBKtFEoQLoO+GNyerfcx95fD3Q KSbF3dBFWTS6dc7i86JTjFbpCjkHe/PiCT/odxUxD346zJDkXwRn3DbuMq3y6VqqE+qCmYQjr1VxW an9YBSgQ==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.98 #2 (Red Hat Linux)) id 1tajh3-0000000BN7j-17ol; Wed, 22 Jan 2025 22:59:29 +0000 Received: from mail-wm1-x336.google.com ([2a00:1450:4864:20::336]) by bombadil.infradead.org with esmtps (Exim 4.98 #2 (Red Hat Linux)) id 1tajfl-0000000BMzF-2YEW for linux-arm-kernel@lists.infradead.org; Wed, 22 Jan 2025 22:58:10 +0000 Received: by mail-wm1-x336.google.com with SMTP id 5b1f17b1804b1-4361f796586so2780085e9.3 for ; Wed, 22 Jan 2025 14:58:08 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20230601; t=1737586687; x=1738191487; darn=lists.infradead.org; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:subject:cc:to:from:date:from:to:cc:subject:date :message-id:reply-to; bh=jqVF0cBTijRuq0m7GTGEM8FFP9eJBtgNqw9jRV9T5lo=; b=DCGWKUnXPX6Z2XgdL+7T/Aux3+cfwYIXdHQwrqqSW8zaX2n7tGta70nU4rv+onzqS8 NI3ax6szDNZiqCVtu2SMw8BwNTdRz5iC+Pcg3rH8vTZZ/B0iYFTOPsBSMajLrGQY45E/ AkxJGSmhZtL2QcxK5Y9AoleSQdx8AvmCVwj2SYorq0xLyPFjEtlliHh8K3yt37jtH0j9 xEogZGAypLMYFqN8QYkmSsc061G2rEM8XT0boAQXhFFRr+wztGUDA/NXhsKgx4SMDQ1/ OINiaddSnseGvs3TYFNvpKN7UqrKAjeNiQ1vXVvYd362+fVWwOlUjFois9fi1HZ2e4Pd 3gPQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1737586687; x=1738191487; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:subject:cc:to:from:date:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=jqVF0cBTijRuq0m7GTGEM8FFP9eJBtgNqw9jRV9T5lo=; b=JkGdAq9b+zTYXFyjsUFlm2kvdWP/PPHSuMTh5DQY5Rm+GfrcfhoOUwOm/5JZaZQeWn voOBfzaZcb+MqwHWLydoj07j8dDtklb/V3AiyAGlxWmQhMZNqoQgLDGs0qZWUsuI6RVo WUeeFsVeX5V7NSZXGwLLvI6r+w2ceSZLFJG4JV8rsV5bhug3r3+qSUWlCvdgcVHN5WrH JQDci9f7u2NT4sZgWoHMwJgHlZCnGDhyuJRu4C581dapfozHBvWfBW/HVdSDd5iECCUk LPr1nU6jOIddHKRyq/jSJ8TvXPQu6L8rC1mpigAJLFtHurNqwl+T5NBlqJAj0CasHEDB Ga/Q== X-Forwarded-Encrypted: i=1; AJvYcCXLDXjLVr2rEcPzkc5Y+hp3zjWQ5I6lwB5HHyIkI/gJInKlT24SqcyTqQ1EtnhOyyyK/d0lmIUxWJhU+Y+1khxt@lists.infradead.org X-Gm-Message-State: AOJu0YyVqdWmp7b1/dNJ4d3pAJqZAAZUv+7sSInmb7ZuOz4E0/vcJqkn Q5HWy2mHSltDEULAGLiEUztqmvjMh5J0X9elhpyPYnPMk/PSItFf X-Gm-Gg: ASbGncuU9PkTlhZtumY/f+dWL32UwNUc9RbWfqwOcJHm7Ktb1djZXps/kWxCZkZakU9 eGuGZAqt2XSr59k2FVwCXaXspweuCPCCam78aEttwqWaJwCEtozBx0FaSTYUtVYc5yjcS21WP/r bmWDPHuZPjlNTsc/k5AtIevBJfwZBuE5hEhM4I1eQZPBnFLEeEpRc/AZS4Qm/17OFwLApbzMCDu JXhsoRzTrV4ftT3KXL0uYWD5MKCEq9Lv86ynbsl7gt8bcmLqlTODPNDlZhw5FQeh5Ec+5dOyE99 ZNntDdDnknwEX37Qlwfkv3PcJZ7VJC83 X-Google-Smtp-Source: AGHT+IEQnQhWcYcYLwtPUsp3QOoc70eLrq7vJCaIVuPYRH/ywGliFi/4zTlOAPB9XOacsMLy93f4rg== X-Received: by 2002:a05:6000:1f88:b0:385:fd31:ca23 with SMTP id ffacd0b85a97d-38bf57a7797mr24374385f8f.40.1737586687462; Wed, 22 Jan 2025 14:58:07 -0800 (PST) Received: from pumpkin (82-69-66-36.dsl.in-addr.zen.co.uk. [82.69.66.36]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-438b31df412sm40115765e9.36.2025.01.22.14.58.06 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 22 Jan 2025 14:58:06 -0800 (PST) Date: Wed, 22 Jan 2025 22:58:05 +0000 From: David Laight To: Anastasia Belova Cc: Emilio =?UTF-8?B?TMOzcGV6?= , Michael Turquette , Stephen Boyd , Chen-Yu Tsai , Jernej Skrabec , Samuel Holland , Hans de Goede , Maxime Ripard , linux-clk@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-sunxi@lists.linux.dev, linux-kernel@vger.kernel.org, lvc-project@linuxtesting.org Subject: Re: [PATCH] clk: sunxi: add explicit casting to prevent overflow Message-ID: <20250122225805.2ba6a062@pumpkin> In-Reply-To: <20250120084719.63116-1-abelova@astralinux.ru> References: <20250120084719.63116-1-abelova@astralinux.ru> X-Mailer: Claws Mail 4.1.1 (GTK 3.24.38; arm-unknown-linux-gnueabihf) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20250122_145809_652355_D27395A4 X-CRM114-Status: GOOD ( 19.09 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Mon, 20 Jan 2025 11:47:16 +0300 Anastasia Belova wrote: > If n = 255, the result of multiplication of n and 24000000 > may not fit int type. Add explicit casting to prevent overflow. > > Found by Linux Verification Center (linuxtesting.org) with SVACE. You need to read and understand the code before writing any patches. The '>> p' and '/ (m + 1)' are both just conditional 'divide by 2'. So can be done before the multiply. Since req->rate is 'signed long' and the value is a frequency it is only just possible that it exceeds 31 bits (and will be wrong on 32bit builds - but sun-9 might be 64bit only?) In any case it would be sensible to force an unsigned divide. So perhaps: unsigned int n = DIV_ROUND_UP(req->rate, 6000000ul); ... req->rate = ((24000000ul >> p) / (m + 1)) * n; David > > Fixes: 6424e0aeebc4 ("clk: sunxi: rewrite sun9i_a80_get_pll4_factors()") > Signed-off-by: Anastasia Belova > --- > drivers/clk/sunxi/clk-sun9i-core.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/drivers/clk/sunxi/clk-sun9i-core.c b/drivers/clk/sunxi/clk-sun9i-core.c > index d93c7a53c6c0..70fbd7390d96 100644 > --- a/drivers/clk/sunxi/clk-sun9i-core.c > +++ b/drivers/clk/sunxi/clk-sun9i-core.c > @@ -50,7 +50,7 @@ static void sun9i_a80_get_pll4_factors(struct factors_request *req) > else if (n < 12) > n = 12; > > - req->rate = ((24000000 * n) >> p) / (m + 1); > + req->rate = ((24000000ULL * n) >> p) / (m + 1); > req->n = n; > req->m = m; > req->p = p;