From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 1139E4594D; Tue, 17 Sep 2024 07:24:32 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1726557873; cv=none; b=DVWGbDZg9GQ+gTUlFQUJqKChTb1CW4p9GjlOXkX/WcWYgEksEW/7vpa28bhFGZngbcO9Dz6K1tGcDtYZwzVsSmyBxlDtX06j2KKhEr63d91XXX6oaIemc1fJP0zFZ0qMDpiLEEjXPIO758PWj/QvdN0eXxO/CqbVYydnM8qn1go= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1726557873; c=relaxed/simple; bh=X8vjfoYlPbAxQw8Py+2hLWq0kqxUupoSphWKecqxkmM=; h=Message-ID:Date:MIME-Version:Subject:From:To:Cc:References: In-Reply-To:Content-Type; b=GxNQLPQftzmTM1swEY0lfjJrR+1ZwvmkPH6xHuRT7t+FYstaFNMw3xEGmp04RCNO50WAOkhDMb/k9/TGeHncb39HmVrX9p1mym7jvCyEu0g5zEEVHi5EHr8508Q/baJnVd/LXLSQx6wOhZXBdoG35/1HdMutKzdBasBpQeUmQ0U= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=B3qEzGn5; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="B3qEzGn5" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 8CEB2C4CEC6; Tue, 17 Sep 2024 07:24:29 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1726557872; bh=X8vjfoYlPbAxQw8Py+2hLWq0kqxUupoSphWKecqxkmM=; h=Date:Subject:From:To:Cc:References:In-Reply-To:From; b=B3qEzGn51fC5JCwWjeiT/tro8LjflbyM4r2j0dtAHC9keNFjiI+LrQbgpnVTyg2xI NdXn3572pA6aYydBt3x2/SCHV+bG9NvnH/rQwlg0O2AxcuVyV15toWrBYRda9dSq9b g55H3km5oaHKZ4Q4Zkm2jgSmx60ZQnK495LRc/AP25nltC1MZ10KuQDYGGBn77k1di N+XNTSBUM8DzOgnT3fGQTAspxa+83mjFVRwCXLjhIPGgfXVN1SOUIINlq8zaLr/8zn A/MWS6fMAjyT4Bs/2h2B4XH0bNbamTKkCHZMzwLdiGEuzrIOCNIgTptiPm2vZbHjHK P+AlN23lWI5Qw== Message-ID: Date: Tue, 17 Sep 2024 09:24:27 +0200 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] nullb: Adjust device size calculation in null_alloc_dev() From: Damien Le Moal To: Aleksandr Mishin , Shaohua Li Cc: Jens Axboe , Hannes Reinecke , Johannes Thumshirn , Chaitanya Kulkarni , Zhu Yanjun , Chengming Zhou , John Garry , Yu Kuai , Shin'ichiro Kawasaki , linux-block@vger.kernel.org, linux-kernel@vger.kernel.org, lvc-project@linuxtesting.org References: <20240917070729.15752-1-amishin@t-argos.ru> Content-Language: en-US Organization: Western Digital Research In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 2024/09/17 16:21, Damien Le Moal wrote: > On 2024/09/17 16:07, Aleksandr Mishin wrote: >> In null_alloc_dev() device size is a subject to overflow because 'g_gb' >> (which is module parameter, may have any value and is not validated >> anywhere) is not cast to a larger data type before performing arithmetic. >> >> Cast 'g_gb' to unsigned long to prevent overflow. >> >> Found by Linux Verification Center (linuxtesting.org) with SVACE. >> >> Fixes: 2984c8684f96 ("nullb: factor disk parameters") >> Signed-off-by: Aleksandr Mishin >> --- >> drivers/block/null_blk/main.c | 2 +- >> 1 file changed, 1 insertion(+), 1 deletion(-) >> >> diff --git a/drivers/block/null_blk/main.c b/drivers/block/null_blk/main.c >> index 2f0431e42c49..5edbf9c0aceb 100644 >> --- a/drivers/block/null_blk/main.c >> +++ b/drivers/block/null_blk/main.c >> @@ -762,7 +762,7 @@ static struct nullb_device *null_alloc_dev(void) >> return NULL; >> } >> >> - dev->size = g_gb * 1024; >> + dev->size = (unsigned long)g_gb * 1024; > > This still does not prevent overflows... So what about doing a proper check ? This still does not prevent overflows on 32-bits architectures. > >> dev->completion_nsec = g_completion_nsec; >> dev->submit_queues = g_submit_queues; >> dev->prev_submit_queues = g_submit_queues; > -- Damien Le Moal Western Digital Research