From: "Andrew F. Davis" <afd@ti.com>
To: Jonathan Cameron <jic23@jic23.retrosnub.co.uk>,
<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 09:11:10 -0400 [thread overview]
Message-ID: <c0e4e79e-2a1a-07cd-dd4b-91a87333bc4f@ti.com> (raw)
In-Reply-To: <83B13776-904F-4FCF-93A6-D430281E4B55@jic23.retrosnub.co.uk>
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.
> 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.
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 13:12 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 [this message]
2020-05-21 14:44 ` Jonathan Cameron
2020-05-21 18:45 ` Jonathan Cameron
2020-05-21 19:05 ` Andrew F. Davis
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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