From: Jonathan Cameron Date: Wed, 22 Jul 2020 15:50:45 +0000 (+0100) Subject: iio:light:max44000 Fix timestamp alignment and prevent data leak. X-Git-Url: https://git.stricted.de/?a=commitdiff_plain;h=866994848683d2d55ca57894ff47babebc6d58a0;p=GitHub%2FLineageOS%2Fandroid_kernel_motorola_exynos9610.git iio:light:max44000 Fix timestamp alignment and prevent data leak. commit 523628852a5f5f34a15252b2634d0498d3cfb347 upstream. 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 16 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(). This data is allocated with kzalloc so no data can leak appart from previous readings. It is necessary to force the alignment of ts to avoid the padding on x86_32 being different from 64 bit platorms (it alows for 4 bytes aligned 8 byte types. Fixes: 06ad7ea10e2b ("max44000: Initial triggered buffer support") Reported-by: Lars-Peter Clausen Signed-off-by: Jonathan Cameron Reviewed-by: Andy Shevchenko Cc: Signed-off-by: Greg Kroah-Hartman --- diff --git a/drivers/iio/light/max44000.c b/drivers/iio/light/max44000.c index 81bd8e8da4a6..255b932fc21d 100644 --- a/drivers/iio/light/max44000.c +++ b/drivers/iio/light/max44000.c @@ -78,6 +78,11 @@ struct max44000_data { struct mutex lock; struct regmap *regmap; + /* Ensure naturally aligned timestamp */ + struct { + u16 channels[2]; + s64 ts __aligned(8); + } scan; }; /* Default scale is set to the minimum of 0.03125 or 1 / (1 << 5) lux */ @@ -492,7 +497,6 @@ static irqreturn_t max44000_trigger_handler(int irq, void *p) struct iio_poll_func *pf = p; struct iio_dev *indio_dev = pf->indio_dev; struct max44000_data *data = iio_priv(indio_dev); - u16 buf[8]; /* 2x u16 + padding + 8 bytes timestamp */ int index = 0; unsigned int regval; int ret; @@ -502,17 +506,17 @@ static irqreturn_t max44000_trigger_handler(int irq, void *p) ret = max44000_read_alsval(data); if (ret < 0) goto out_unlock; - buf[index++] = ret; + data->scan.channels[index++] = ret; } if (test_bit(MAX44000_SCAN_INDEX_PRX, indio_dev->active_scan_mask)) { ret = regmap_read(data->regmap, MAX44000_REG_PRX_DATA, ®val); if (ret < 0) goto out_unlock; - buf[index] = regval; + data->scan.channels[index] = regval; } mutex_unlock(&data->lock); - iio_push_to_buffers_with_timestamp(indio_dev, buf, + iio_push_to_buffers_with_timestamp(indio_dev, &data->scan, iio_get_time_ns(indio_dev)); iio_trigger_notify_done(indio_dev->trig); return IRQ_HANDLED;