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 4385D1D63E8; Tue, 26 Nov 2024 18:52:19 +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=1732647140; cv=none; b=mQ2SK4FdAR8HMgNXlfrftxdXj5z4zAiKmZV9HrX4HXkVnJlKpXwaCPLBX5+ys+CZ6FTBkGwIW0N0rMqHr8jRGKQ8Km8dnlmMmRJWv+az6Pp+sY8h2GDmyJQ0KxLbgoDbKljqA3qOee3hn2s3SxkiBchTaR0IAol4o1Yf4rmSyFI= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1732647140; c=relaxed/simple; bh=5vy3ETKoRBehBMtsbIQQeHicXBlDE6OcnPhy+O5N65U=; h=Date:From:To:Cc:Subject:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=YZ4Is65zYf5boTqQlzyOSdRxuythDGZw+aSRkpMoBW0iLCqMlPuRPc4dPxEDLARZSGdL3cviDmwZ7bijj5ltb8yUthYbpgCK71zaNOvkeIbmyMXtvZVc8nd2CWlKeyKgdBbIQx0i+rzYS7w7rom/z02y6Gzj/ypgKae+nK21FzE= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=OjXl7Fiq; 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="OjXl7Fiq" Received: by smtp.kernel.org (Postfix) with ESMTPSA id C1E70C4CECF; Tue, 26 Nov 2024 18:52:16 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1732647139; bh=5vy3ETKoRBehBMtsbIQQeHicXBlDE6OcnPhy+O5N65U=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=OjXl7FiqYgkanSgMqRUgFZWhsrDscNA+htu1e6t6nN5DLEX8UEG9SzSZLtvQ8AlBY qhQOSCdfKQopnT/bOHU3QEVGQAypBhpBlm0e6H8tzl5thIJ+OmWlElQosPKHmwVtMs 3rHnbVnliHXut4vSM647M9wItEwWOr/4WBUiXjI1Ac7CDFR705nrICK5+Za3SwxOwf nhobSZ8YJ89mAmp1eBobO+6noWEmR5zYir8ec++WW3aYCkRnBs59rypJNxwI3u84iI taute58duUWn4j/cb7N48EqILhLC+sBnjXuGjN7X5/1RP5dIb3Udxa6Uni8XDDziHo UV4r33tyZjpWA== Date: Tue, 26 Nov 2024 18:52:11 +0000 From: Jonathan Cameron To: Javier Carrasco Cc: Francesco Dolcini , Lars-Peter Clausen , Antoni Pokusinski , =?UTF-8?B?Sm/Do28=?= Paulo =?UTF-8?B?R29uw6dhbHZlcw==?= , Gregor Boirie , Jonathan Cameron , linux-iio@vger.kernel.org, linux-kernel@vger.kernel.org, =?UTF-8?B?Sm8=?= =?UTF-8?B?w6Nv?= Paulo =?UTF-8?B?R29uw6dhbHZlcw==?= , Francesco Dolcini , stable@vger.kernel.org Subject: Re: [PATCH 02/11] iio: adc: ti-ads1119: fix information leak in triggered buffer Message-ID: <20241126185211.385f82c4@jic23-huawei> In-Reply-To: <59a4b096-101b-419d-8a19-1063d759b4e2@gmail.com> References: <20241125-iio_memset_scan_holes-v1-0-0cb6e98d895c@gmail.com> <20241125-iio_memset_scan_holes-v1-2-0cb6e98d895c@gmail.com> <20241126085958.GA13577@francesco-nb> <59a4b096-101b-419d-8a19-1063d759b4e2@gmail.com> X-Mailer: Claws Mail 4.3.0 (GTK 3.24.43; x86_64-pc-linux-gnu) Precedence: bulk X-Mailing-List: linux-iio@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit On Tue, 26 Nov 2024 10:46:37 +0100 Javier Carrasco wrote: > On 26/11/2024 09:59, Francesco Dolcini wrote: > > On Mon, Nov 25, 2024 at 10:16:10PM +0100, Javier Carrasco wrote: > >> The 'scan' local struct is used to push data to user space from a > >> triggered buffer, but it has a hole between the sample (unsigned int) > >> and the timestamp. This hole is never initialized. > >> > >> Initialize the struct to zero before using it to avoid pushing > >> uninitialized information to userspace. > >> > >> Cc: stable@vger.kernel.org > >> Fixes: a9306887eba4 ("iio: adc: ti-ads1119: Add driver") > >> Signed-off-by: Javier Carrasco > >> --- > >> drivers/iio/adc/ti-ads1119.c | 2 ++ > >> 1 file changed, 2 insertions(+) > >> > >> diff --git a/drivers/iio/adc/ti-ads1119.c b/drivers/iio/adc/ti-ads1119.c > >> index e9d9d4d46d38..2615a275acb3 100644 > >> --- a/drivers/iio/adc/ti-ads1119.c > >> +++ b/drivers/iio/adc/ti-ads1119.c > >> @@ -506,6 +506,8 @@ static irqreturn_t ads1119_trigger_handler(int irq, void *private) > >> unsigned int index; > >> int ret; > >> > >> + memset(&scan, 0, sizeof(scan)); > > > > Did you consider adding a reserved field after sample and just > > initializing that one to zero? > > > > It seems a trivial optimization not adding much value, but I thought about > > it, so I'd like to be sure you considered it. > > > > In any case, the change is fine. > > > > Reviewed-by: Francesco Dolcini > > > > Thanks, > > Francesco > > > > Hi Francesco, thanks for your review. > > In this particular case where unsigned int is used for the sample, the > padding would _in theory_ depend on the architecture. The size of the > unsigned int is usually 4 bytes, but the standard only specifies that it > must be able to contain values in the [0, 65535] range i.e. 2 bytes. > That is indeed theory, and I don't know if there is a real case where a > new version of Linux is able to run on an architecture that uses 2 bytes > for an int. I guess there is not, but better safe than sorry. Using an unsigned int here is a bug as well as we should present consistent formatted data whatever the architecture. > > We could be more specific with u32 for the sample and then add the > reserved field, but I would still prefer a memset() for this small > struct. Adding and initializing a reserved field looks a bit artificial > to me, especially for such marginal gains. Issue with reserved fields is we would have to be very very careful to spot them all. A memset avoids that care being needed. Jonathan > > Moreover, the common practice (at least in IIO)is a plain memset() to > initialize struct holes, and such common patterns are easier to maintain :) > > Best regards, > Javier Carrasco