From: Sasha Levin <sashal@kernel.org>
To: linux-kernel@vger.kernel.org, stable@vger.kernel.org
Cc: Bastien Nocera <hadess@hadess.net>,
Jonathan Cameron <Jonathan.Cameron@huawei.com>,
Sasha Levin <sashal@kernel.org>,
linux-iio@vger.kernel.org
Subject: [PATCH AUTOSEL 5.2 090/171] iio: iio-utils: Fix possible incorrect mask calculation
Date: Thu, 18 Jul 2019 23:55:21 -0400 [thread overview]
Message-ID: <20190719035643.14300-90-sashal@kernel.org> (raw)
In-Reply-To: <20190719035643.14300-1-sashal@kernel.org>
From: Bastien Nocera <hadess@hadess.net>
[ Upstream commit 208a68c8393d6041a90862992222f3d7943d44d6 ]
On some machines, iio-sensor-proxy was returning all 0's for IIO sensor
values. It turns out that the bits_used for this sensor is 32, which makes
the mask calculation:
*mask = (1 << 32) - 1;
If the compiler interprets the 1 literals as 32-bit ints, it generates
undefined behavior depending on compiler version and optimization level.
On my system, it optimizes out the shift, so the mask value becomes
*mask = (1) - 1;
With a mask value of 0, iio-sensor-proxy will always return 0 for every axis.
Avoid incorrect 0 values caused by compiler optimization.
See original fix by Brett Dutro <brett.dutro@gmail.com> in
iio-sensor-proxy:
https://github.com/hadess/iio-sensor-proxy/commit/9615ceac7c134d838660e209726cd86aa2064fd3
Signed-off-by: Bastien Nocera <hadess@hadess.net>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
tools/iio/iio_utils.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/tools/iio/iio_utils.c b/tools/iio/iio_utils.c
index a22b6e8fad46..7399eb7f1378 100644
--- a/tools/iio/iio_utils.c
+++ b/tools/iio/iio_utils.c
@@ -156,9 +156,9 @@ int iioutils_get_type(unsigned *is_signed, unsigned *bytes, unsigned *bits_used,
*be = (endianchar == 'b');
*bytes = padint / 8;
if (*bits_used == 64)
- *mask = ~0;
+ *mask = ~(0ULL);
else
- *mask = (1ULL << *bits_used) - 1;
+ *mask = (1ULL << *bits_used) - 1ULL;
*is_signed = (signchar == 's');
if (fclose(sysfsfp)) {
--
2.20.1
prev parent reply other threads:[~2019-07-19 4:37 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20190719035643.14300-1-sashal@kernel.org>
2019-07-19 3:53 ` [PATCH AUTOSEL 5.2 003/171] iio: adc: stm32-dfsdm: manage the get_irq error case Sasha Levin
2019-07-19 3:53 ` [PATCH AUTOSEL 5.2 004/171] iio: adc: stm32-dfsdm: missing error case during probe Sasha Levin
2019-07-19 3:54 ` [PATCH AUTOSEL 5.2 064/171] iio:core: Fix bug in length of event info_mask and catch unhandled bits set in masks Sasha Levin
2019-07-19 3:54 ` [PATCH AUTOSEL 5.2 065/171] iio: adxl372: fix iio_triggered_buffer_{pre,post}enable positions Sasha Levin
2019-07-19 3:55 ` [PATCH AUTOSEL 5.2 084/171] iio: st_accel: " Sasha Levin
2019-07-19 3:55 ` Sasha Levin [this message]
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