From: "Andrew F. Davis" <afd@ti.com>
To: Jonathan Cameron <jic23@kernel.org>, <linux-iio@vger.kernel.org>
Cc: Jonathan Cameron <Jonathan.Cameron@huawei.com>,
Lars-Peter Clausen <lars@metafoo.de>
Subject: Re: [PATCH 07/11] iio:health:afe4403 Fix timestamp alignment and prevent data leak.
Date: Thu, 21 May 2020 15:05:37 -0400 [thread overview]
Message-ID: <e28e67c9-a234-64da-2839-9434fc62c6ec@ti.com> (raw)
In-Reply-To: <20200521194530.08706fee@archlinux>
On 5/21/20 2:45 PM, Jonathan Cameron wrote:
> On Thu, 21 May 2020 15:44:43 +0100
> Jonathan Cameron <jic23@jic23.retrosnub.co.uk> wrote:
>
>> On 21 May 2020 14:11:10 BST, "Andrew F. Davis" <afd@ti.com> wrote:
>>>
>>>
>>> On 5/18/20 12:06 PM, Jonathan Cameron wrote:
>>>>
>>>>
>>>> On 18 May 2020 01:09:47 BST, "Andrew F. Davis" <afd@ti.com> wrote:
>>>>> On 5/17/20 1:29 PM, 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 32 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 structure in the iio_priv() data with
>>> alignment
>>>>>> explicitly requested. This data is allocated with kzalloc so no
>>>>>> data can leak appart from previous readings.
>>>>>>
>>>>>> Fixes: eec96d1e2d31 ("iio: health: Add driver for the TI AFE4403
>>>>> heart monitor")
>>>>>> Reported-by: Lars-Peter Clausen <lars@metafoo.de>
>>>>>> Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
>>>>>> Cc: Andrew F. Davis <afd@ti.com>
>>>>>> ---
>>>>>> drivers/iio/health/afe4403.c | 9 ++++++---
>>>>>> 1 file changed, 6 insertions(+), 3 deletions(-)
>>>>>>
>>>>>> diff --git a/drivers/iio/health/afe4403.c
>>>>> b/drivers/iio/health/afe4403.c
>>>>>> index e9f87e42ff4f..a3507624b30f 100644
>>>>>> --- a/drivers/iio/health/afe4403.c
>>>>>> +++ b/drivers/iio/health/afe4403.c
>>>>>> @@ -65,6 +65,7 @@ static const struct reg_field
>>> afe4403_reg_fields[]
>>>>> = {
>>>>>> * @regulator: Pointer to the regulator for the IC
>>>>>> * @trig: IIO trigger for this device
>>>>>> * @irq: ADC_RDY line interrupt number
>>>>>> + * @buffer: Used to construct data layout to push into IIO buffer.
>>>>>> */
>>>>>> struct afe4403_data {
>>>>>> struct device *dev;
>>>>>> @@ -74,6 +75,8 @@ struct afe4403_data {
>>>>>> struct regulator *regulator;
>>>>>> struct iio_trigger *trig;
>>>>>> int irq;
>>>>>> + /* Ensure suitable alignment for timestamp */
>>>>>> + s32 buffer[8] __aligned(8);
>>>>>
>>>>>
>>>>> One of those fancy structs with the timestamp specified would be
>>> nice
>>>>> here like the other patches. IIRC we have 6 s32 channels, plus a s64
>>>>> ts.
>>>>
>>>> I think we may only have some of those channels enabled. So ts may
>>> be it several
>>>> locations in the buffer.
>>>>
>>>
>>> Might have been better to have the ts at the beginning, could have also
>>> helped with alignment for when an odd number of channels are enabled.
>>
>> Perhaps but for many use cases we don't turn timestamps on and we would need to pad
>> anyway for alignment of the fifo.
>>
>>>
>>>> Hence we could use the structure approach but it might give a false
>>> sense
>>>> of what is going on.
>>>>
>>>
>>> That's true, it can always be cleaned later then.
>>
>> Agreed. This is definitely something we can revisit sometime in the future.
>
> Formal Ack on applying the two afe patches?
>
Acked-by: Andrew F. Davis <afd@ti.com>
> Thanks,
>
> Jonathan
>>
>> J
>>>
>>> Andrew
>>>
>>>> J
>>>>>
>>>>> Other than that everything looks good.
>>>>>
>>>>> Andrew
>>>>>
>>>>>
>>>>>> };
>>>>>>
>>>>>> enum afe4403_chan_id {
>>>>>> @@ -309,7 +312,6 @@ static irqreturn_t afe4403_trigger_handler(int
>>>>> irq, void *private)
>>>>>> struct iio_dev *indio_dev = pf->indio_dev;
>>>>>> struct afe4403_data *afe = iio_priv(indio_dev);
>>>>>> int ret, bit, i = 0;
>>>>>> - s32 buffer[8];
>>>>>> u8 tx[4] = {AFE440X_CONTROL0, 0x0, 0x0, AFE440X_CONTROL0_READ};
>>>>>> u8 rx[3];
>>>>>>
>>>>>> @@ -326,7 +328,7 @@ static irqreturn_t afe4403_trigger_handler(int
>>>>> irq, void *private)
>>>>>> if (ret)
>>>>>> goto err;
>>>>>>
>>>>>> - buffer[i++] = get_unaligned_be24(&rx[0]);
>>>>>> + afe->buffer[i++] = get_unaligned_be24(&rx[0]);
>>>>>> }
>>>>>>
>>>>>> /* Disable reading from the device */
>>>>>> @@ -335,7 +337,8 @@ static irqreturn_t afe4403_trigger_handler(int
>>>>> irq, void *private)
>>>>>> if (ret)
>>>>>> goto err;
>>>>>>
>>>>>> - iio_push_to_buffers_with_timestamp(indio_dev, buffer,
>>>>> pf->timestamp);
>>>>>> + iio_push_to_buffers_with_timestamp(indio_dev, afe->buffer,
>>>>>> + pf->timestamp);
>>>>>> err:
>>>>>> iio_trigger_notify_done(indio_dev->trig);
>>>>>>
>>>>>>
>>>>
>>
>
next prev parent reply other threads:[~2020-05-21 19:06 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-05-17 17:29 [PATCH 00/11] IIO: 1st set of timestamp alignment fixes jic23
2020-05-17 17:29 ` [PATCH 01/11] iio: accel: kxsd9: Fix alignment of local buffer jic23
2020-05-17 17:29 ` [PATCH 02/11] iio:accel:mma8452: Fix timestamp alignment and prevent data leak jic23
2020-05-17 18:57 ` Lars-Peter Clausen
2020-05-18 16:37 ` Jonathan Cameron
2020-05-17 17:29 ` [PATCH 03/11] iio:accel:bmc150-accel: " jic23
2020-05-17 17:29 ` [PATCH 04/11] iio:accel:mma7455: " jic23
2020-05-17 17:29 ` [PATCH 05/11] iio:gyro:itg3200: " jic23
2020-05-17 17:29 ` [PATCH 06/11] iio:proximity:mb1232: " jic23
2020-05-17 17:29 ` [PATCH 07/11] iio:health:afe4403 " jic23
2020-05-18 0:09 ` Andrew F. Davis
2020-05-18 16:06 ` Jonathan Cameron
2020-05-21 13:11 ` Andrew F. Davis
2020-05-21 14:44 ` Jonathan Cameron
2020-05-21 18:45 ` Jonathan Cameron
2020-05-21 19:05 ` Andrew F. Davis [this message]
2020-05-24 15:33 ` Jonathan Cameron
2020-05-17 17:29 ` [PATCH 08/11] iio:health:afe4404 " jic23
2020-05-24 15:34 ` Jonathan Cameron
2020-05-17 17:29 ` [PATCH 09/11] iio:chemical:ccs811: " jic23
2020-05-17 17:29 ` [PATCH 10/11] iio:chemical:sps30: Fix timestamp alignment jic23
2020-05-17 19:07 ` Tomasz Duszynski
2020-05-21 18:43 ` Jonathan Cameron
2020-05-17 17:30 ` [PATCH 11/11] iio:chemical:pms7003: Fix timestamp alignment and prevent data leak jic23
2020-05-17 19:06 ` Tomasz Duszynski
2020-05-21 18:44 ` Jonathan Cameron
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