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From: Andy Shevchenko <andy.shevchenko@gmail.com>
To: Jonathan Cameron <jic23@kernel.org>
Cc: linux-iio <linux-iio@vger.kernel.org>,
	Lars-Peter Clausen <lars@metafoo.de>,
	Peter Meerwald <pmeerw@pmeerw.net>,
	Jonathan Cameron <Jonathan.Cameron@huawei.com>
Subject: Re: [PATCH v3 08/27] iio:light:si1145: Fix timestamp alignment and prevent data leak.
Date: Wed, 22 Jul 2020 22:45:59 +0300	[thread overview]
Message-ID: <CAHp75VcL+-jxYiNVkXi=s8WDRvDuSVJ9w9AtKsKVp2eN_TEtXA@mail.gmail.com> (raw)
In-Reply-To: <CAHp75VdFQYtkA-g2S=Vcvk3Sxp7duTihr3XGfzbUEB5xM4UbTg@mail.gmail.com>

On Wed, Jul 22, 2020 at 10:43 PM Andy Shevchenko
<andy.shevchenko@gmail.com> wrote:
>
> On Wed, Jul 22, 2020 at 6:53 PM Jonathan Cameron <jic23@kernel.org> wrote:
> >
> > From: Jonathan Cameron <Jonathan.Cameron@huawei.com>
> >
> > One of a class of bugs pointed out by Lars in a recent review.
> > iio_push_to_buffers_with_timestamp assumes the buffer used is aligned
> > to the size of the timestamp (8 bytes).  This is not guaranteed in
> > this driver which uses a 24 byte array of smaller elements on the stack.
> > As Lars also noted this anti pattern can involve a leak of data to
> > userspace and that indeed can happen here.  We close both issues by
> > moving to a suitable array in the iio_priv() data with alignment
> > explicitly requested.  This data is allocated with kzalloc so no
> > data can leak appart from previous readings.
> >
> > Depending on the enabled channels, the  location of the timestamp
> > can be at various aligned offsets through the buffer.  As such we
> > any use of a structure to enforce this alignment would incorrectly
> > suggest a single location for the timestamp.
>
> ...
>
> > +       /* Ensure timestamp will be naturally aligned if present */
> > +       u8 buffer[24] __aligned(8);
>
> Why can't we use proper structure here?
>
> > @@ -445,7 +447,6 @@ static irqreturn_t si1145_trigger_handler(int irq, void *private)
> >          *   6*2 bytes channels data + 4 bytes alignment +
> >          *   8 bytes timestamp
> >          */
> > -       u8 buffer[24];
>
> Seems even the old comment shows how it should look like...

I think I understand now. Basically it's a dynamic amount of channels
(up to 6) before you get a timestamp.

-- 
With Best Regards,
Andy Shevchenko

  reply	other threads:[~2020-07-22 19:46 UTC|newest]

Thread overview: 72+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-07-22 15:50 [PATCH v3 00/27] IIO: Fused set 1 and 2 of timestamp alignment fixes Jonathan Cameron
2020-07-22 15:50 ` [PATCH v3 01/27] iio: accel: kxsd9: Fix alignment of local buffer Jonathan Cameron
2020-08-09 17:07   ` Jonathan Cameron
2020-07-22 15:50 ` [PATCH v3 02/27] iio:accel:mma8452: Fix timestamp alignment and prevent data leak Jonathan Cameron
2020-08-09 17:14   ` Jonathan Cameron
2020-07-22 15:50 ` [PATCH v3 03/27] iio:accel:bmc150-accel: " Jonathan Cameron
2020-07-29 17:12   ` Srinivas Pandruvada
2020-08-09 17:18     ` Jonathan Cameron
2020-07-22 15:50 ` [PATCH v3 04/27] iio:accel:mma7455: " Jonathan Cameron
2020-08-09 17:19   ` Jonathan Cameron
2020-07-22 15:50 ` [PATCH v3 05/27] iio:gyro:itg3200: " Jonathan Cameron
2020-09-19 15:41   ` Jonathan Cameron
2020-07-22 15:50 ` [PATCH v3 06/27] iio:proximity:mb1232: " Jonathan Cameron
2020-08-09 17:20   ` Jonathan Cameron
2020-07-22 15:50 ` [PATCH v3 07/27] iio:chemical:ccs811: " Jonathan Cameron
2020-08-09 17:23   ` Jonathan Cameron
2020-07-22 15:50 ` [PATCH v3 08/27] iio:light:si1145: " Jonathan Cameron
2020-07-22 19:43   ` Andy Shevchenko
2020-07-22 19:45     ` Andy Shevchenko [this message]
2020-07-23 11:25       ` Jonathan Cameron
2020-09-19 15:46         ` Jonathan Cameron
2020-07-22 15:50 ` [PATCH v3 09/27] iio:light:max44000 " Jonathan Cameron
2020-08-09 17:24   ` Jonathan Cameron
2020-07-22 15:50 ` [PATCH v3 10/27] iio:light:rpr0521 " Jonathan Cameron
2020-07-22 19:47   ` Andy Shevchenko
2020-07-23 11:29     ` Jonathan Cameron
2020-09-19 16:31       ` Jonathan Cameron
2020-07-22 15:50 ` [PATCH v3 11/27] iio:light:st_uvis25 " Jonathan Cameron
2020-07-22 19:48   ` Andy Shevchenko
2020-07-22 15:50 ` [PATCH v3 12/27] iio:light:ltr501 Fix timestamp alignment issue Jonathan Cameron
2020-08-09 17:27   ` Jonathan Cameron
2020-07-22 15:50 ` [PATCH v3 13/27] iio:magnetometer:ak8975 Fix alignment and data leak issues Jonathan Cameron
2020-08-09 17:30   ` Jonathan Cameron
2020-07-22 15:50 ` [PATCH v3 14/27] iio:magnetometer:mag3110 " Jonathan Cameron
2020-07-23 12:13   ` Andy Shevchenko
2020-07-22 15:50 ` [PATCH v3 15/27] iio:imu:bmi160 " Jonathan Cameron
2020-09-19 15:58   ` Jonathan Cameron
2020-07-22 15:50 ` [PATCH v3 16/27] iio:imu:st_lsm6dsx " Jonathan Cameron
2020-09-19 16:09   ` Jonathan Cameron
2020-07-22 15:50 ` [PATCH v3 17/27] iio:imu:inv_mpu6050 Fix dma and ts " Jonathan Cameron
2020-07-24  8:27   ` Jean-Baptiste Maneyrol
2020-09-19 16:51     ` Jonathan Cameron
2020-07-22 15:50 ` [PATCH v3 18/27] iio:imu:inv_mpu6050: Use regmap_noinc_read for fifo reads Jonathan Cameron
2020-07-23 12:15   ` Andy Shevchenko
2020-07-23 12:28     ` Jonathan Cameron
2020-07-24  8:29   ` Jean-Baptiste Maneyrol
2020-09-19 16:55     ` Jonathan Cameron
2020-07-22 15:50 ` [PATCH v3 19/27] iio:pressure:mpl3115 Force alignment of buffer Jonathan Cameron
2020-07-23 12:17   ` Andy Shevchenko
2020-07-23 12:31     ` Jonathan Cameron
2020-09-19 17:02       ` Jonathan Cameron
2020-07-22 15:50 ` [PATCH v3 20/27] iio:adc:ti-adc081c Fix alignment and data leak issues Jonathan Cameron
2020-08-09 17:34   ` Jonathan Cameron
2020-07-22 15:50 ` [PATCH v3 21/27] iio:adc:ti-adc084s021 " Jonathan Cameron
2020-08-09 17:36   ` Jonathan Cameron
2020-07-22 15:50 ` [PATCH v3 22/27] iio:adc:ti-adc084s021 Tidy up endian types Jonathan Cameron
2020-08-09 17:47   ` Jonathan Cameron
2020-09-13 12:01     ` Jonathan Cameron
2020-09-13 12:06       ` Jonathan Cameron
2020-11-29 13:28         ` Jonathan Cameron
2020-07-22 15:50 ` [PATCH v3 23/27] iio:adc:ti-ads124s08 Fix alignment and data leak issues Jonathan Cameron
2020-07-22 20:54   ` Andy Shevchenko
2020-07-23 11:23     ` Jonathan Cameron
2020-07-22 15:51 ` [PATCH v3 24/27] iio:adc:ti-adc0832 Fix alignment issue with timestamp Jonathan Cameron
2020-09-19 16:18   ` Jonathan Cameron
2020-07-22 15:51 ` [PATCH v3 25/27] iio:adc:ti-adc12138 " Jonathan Cameron
2020-09-19 16:21   ` Jonathan Cameron
2020-07-22 15:51 ` [PATCH v3 26/27] iio:adc:ina2xx Fix timestamp alignment issue Jonathan Cameron
2020-08-09 17:38   ` Jonathan Cameron
2020-07-22 15:51 ` [PATCH v3 27/27] iio:adc:max1118 Fix alignment of timestamp and data leak issues Jonathan Cameron
2020-08-09 17:39   ` Jonathan Cameron
2020-07-23 12:23 ` [PATCH v3 00/27] IIO: Fused set 1 and 2 of timestamp alignment fixes Andy Shevchenko

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