On off chance someone reads the cover letter. Note that there is a big problem with both this and the previous series, so there will be a v2. Sorry about that an thank to Andy for a quick review. Jonathan On Mon, 25 May 2020 18:06:03 +0100 Jonathan Cameron <jic23@xxxxxxxxxx> wrote: > From: Jonathan Cameron <Jonathan.Cameron@xxxxxxxxxx> > > Note there are still quite a few in the first set [2] that I have not > picked up yet due to lack of review. Any help with sanity checking > those (and these) would be much appreciated. These are not quite > mechanical enough for me to be sure I haven't done anything silly > so the more eyes the better. Also see that discussion for extra > details on why I went in various directions to fix this in the > different drivers. > > I've mostly avoided simply using __aligned(8) on the stack because > it is only relatively recently that that has been guaranteed to work. > Gcc 4.6 and kernel 4.19. I'd like it to be sensible to backport > most of these without significant rework. The mpl3115 is I think the > only exception. > > I also snuck in a warning fix for endian casting as it was in the code > that I was touching to do the main fix. > > So what's left from Lars list? 5 harder cases where I'm either fairly > sure there are other bugs in the code, or I simply couldn't face > figuring them out today. > > Anyhow, to recap - round 1 cover letter. > > Lars noted in a recent review [1] of the adis16475 that we had an issue around > the alignment requirements of iio_push_to_buffers_with_timestamp. > Whilst it's not documented, that function assumes that the overall buffer > is 8 byte aligned, to ensure the timestamp is itself naturally aligned. > We have drivers that use arrays (typically on the stack) that do > not guarantee this alignment. > > We could have fixed this by using a put_unaligned to write the timestamp > but I think that just pushes the problem down the line. If we were to > have a consumer buffer wanting all the channels in the current > active_scanmask then it will get the raw buffer from the driver passed > straight through. It seems odd to me if we allow passing a buffer > that is not naturally aligned through to a consumer. > Hence I'm proposing to fix up all existing drivers that might pass > a buffer with insufficient alignment guarantees. > Sometimes the timestamp is guaranteed to be in a particular location, > in which case we can use C structure alignment guarantees to fix this > in a nice readable fashion. In other cases, the timestamp location > depends on which channels are enabled, and in those case we can > use explicit alignment __aligned(8) to ensure the whole array is > appropriately aligned. > > Lars-Peter also noted that, in many of these cases, there are holes > in the stack array that we never write. Those provide a potential > leak of kernel data to userspace. For drivers where this applies > we either need to zero those holes each time, or allocate the buffer > on the heap (only once), ensuring it is zeroed at that time. > We may leak previous values from the sensor but currently that seems > unlikely to present any form of security risk. > > As such, this first set contains a mixture of fixes. Where there > are no possible holes, the buffer is kept on the stack but a > c structure is used to guarantee appropriate alignment. Where > there are holes, the buffer is moved into the iio_priv() accessed > data private structure. A c structure or __aligned(8) is used > as appropriate. > > I've stopped at this point rather than doing all the drivers Lars > found in order to both throttle the review burden and also to > see find any general problems with the fixes before doign futher > similar series. A few of the remaining ones will be rather more > complex to deal with. > > These have been there a long time, so whilst they are fixes we > will want in stable I'm not that bothered if it takes us a little > while to get them there! > > [1] https://www.spinics.net/lists/devicetree/msg350590.html > [2] https://patchwork.kernel.org/cover/11554215/ > > Jonathan Cameron (25): > iio:light:si1145: Fix timestamp alignment and prevent data leak. > iio:light:max44000 Fix timestamp alignment and prevent data leak. > iio:light:rpr0521 Fix timestamp alignment and prevent data leak. > iio:light:st_uvis25 Fix timestamp alignment and prevent data leak. > iio:light:ltr501 Fix timestamp alignment issue. > iio:magnetometer:ak8974: Fix alignment and data leak issues > iio:magnetometer:ak8975 Fix alignment and data leak issues. > iio:magnetometer:mag3110 Fix alignment and data leak issues. > iio:humidity:hdc100x Fix alignment and data leak issues > iio:humidity:hts221 Fix alignment and data leak issues > iio:imu:bmi160 Fix alignment and data leak issues > iio:imu:st_lsm6dsx Fix alignment and data leak issues > iio:imu:inv_mpu6050 Fix dma and ts alignment and data leak issues. > iio:pressure:ms5611 Fix buffer element alignment > iio:pressure:mpl3115 Force alignment of buffer > iio:adc:ti-adc081c Fix alignment and data leak issues > iio:adc:ti-adc084s021 Fix alignment and data leak issues. > iio:adc:ti-adc084s021 Tidy up endian types > iio:adc:ti-ads1015 Fix buffer element alignment > iio:adc:ti-ads124s08 Fix alignment and data leak issues. > iio:adc:ti-ads8688 Fix alignment and potential data leak issue > iio:adc:ti-adc0832 Fix alignment issue with timestamp > iio:adc:ti-adc12138 Fix alignment issue with timestamp > iio:adc:ina2xx Fix timestamp alignment issue. > iio:adc:max1118 Fix alignment of timestamp and data leak issues > > drivers/iio/adc/ina2xx-adc.c | 8 +++--- > drivers/iio/adc/max1118.c | 10 ++++--- > drivers/iio/adc/ti-adc081c.c | 11 +++++--- > drivers/iio/adc/ti-adc0832.c | 7 ++--- > drivers/iio/adc/ti-adc084s021.c | 20 ++++++++------ > drivers/iio/adc/ti-adc12138.c | 9 ++++--- > drivers/iio/adc/ti-ads1015.c | 12 ++++++--- > drivers/iio/adc/ti-ads124s08.c | 10 ++++--- > drivers/iio/adc/ti-ads8688.c | 12 ++++++--- > drivers/iio/humidity/hdc100x.c | 10 ++++--- > drivers/iio/humidity/hts221.h | 5 ++++ > drivers/iio/humidity/hts221_buffer.c | 9 ++++--- > drivers/iio/imu/bmi160/bmi160.h | 2 ++ > drivers/iio/imu/bmi160/bmi160_core.c | 5 ++-- > drivers/iio/imu/inv_mpu6050/inv_mpu_iio.h | 8 +++--- > drivers/iio/imu/inv_mpu6050/inv_mpu_ring.c | 12 ++++----- > drivers/iio/imu/st_lsm6dsx/st_lsm6dsx.h | 5 ++++ > .../iio/imu/st_lsm6dsx/st_lsm6dsx_buffer.c | 27 ++++++++++--------- > drivers/iio/light/ltr501.c | 15 ++++++----- > drivers/iio/light/max44000.c | 12 ++++++--- > drivers/iio/light/rpr0521.c | 17 +++++++++--- > drivers/iio/light/si1145.c | 7 ++--- > drivers/iio/light/st_uvis25.h | 5 ++++ > drivers/iio/light/st_uvis25_core.c | 6 ++--- > drivers/iio/magnetometer/ak8974.c | 10 ++++--- > drivers/iio/magnetometer/ak8975.c | 20 +++++++++----- > drivers/iio/magnetometer/mag3110.c | 13 ++++++--- > drivers/iio/pressure/mpl3115.c | 3 ++- > drivers/iio/pressure/ms5611_core.c | 11 +++++--- > 29 files changed, 198 insertions(+), 103 deletions(-) >
