From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 98311319601; Thu, 16 Jul 2026 14:01:11 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784210472; cv=none; b=k+y/RwxunTwiW5nmqJPjAkmEb3qNRD3f+xL6FvWCrs3c1TIj9MSHWtWIIn5h8/d6rDFpKnZ/0OfKibZ1QTNP7cDvlzJY95ouRWYV0z5u8rwE2HuEzkA2G8Nk9uzqUi98UkmTwM5XsCZiVPFRroYnO+9eH6OGUJU9//+9blQt5EY= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784210472; c=relaxed/simple; bh=DAnSGPCi/ArV6A/LB+/L6rr0qmRXWKH7zmq1qubp2bw=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=Nkkf7fPkr4gVVyHyxCPVJ/lte/ZwvM4KAW9roL1OOvUGR2KXH5Avap2nUkWvNWnFcD2XRfoykmja9Af17EUJqXDnUamw9qvVtOkofK7aLqJOrfwHDFcEVAV3yKeKkDzJGMTCd/tgW9vt6P1hzQsTjFQKnpvoQJkBkzZbyT9qarQ= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=aITbFDp4; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="aITbFDp4" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 051A01F000E9; Thu, 16 Jul 2026 14:01:10 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1784210471; bh=3nrxcanh2Rf4k8+dodCA5X0eIuqXXbybZhiZNKvgts8=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=aITbFDp4LXJeaWPIkMkCkEZq9MEirtwyh8KU2B85a6DZrHbnAQeN9XsE71rvWyFJE 3xBAzE4759aNcZDm0vNEVBoyTtg0ncEdFNsWpHXMYmuJxsa67XjVhka2zXz44qSsSz G5FvRhzjgFlIiKPsOSb8OCcU3AbV+bPXCyDuK9ok= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Herman van Hazendonk , Andy Shevchenko , Jonathan Cameron Subject: [PATCH 6.18 061/480] iio: common: st_sensors: honour channel endianness in read_axis_data Date: Thu, 16 Jul 2026 15:26:48 +0200 Message-ID: <20260716133046.030300973@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260716133044.672218725@linuxfoundation.org> References: <20260716133044.672218725@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 6.18-stable review patch. If anyone has any objections, please let me know. ------------------ From: Herman van Hazendonk commit 55052184ac9011db2ea983e54d6c21f0b1079a12 upstream. st_sensors_read_axis_data() unconditionally decoded multi-byte results with get_unaligned_le16() / get_unaligned_le24() regardless of the channel's declared scan_type.endianness. For every ST sensor that has used this helper since it was introduced this happened to be fine because the ST IMU/accel/gyro/pressure families publish their data registers as little-endian and the channel specs in those drivers declare IIO_LE accordingly. The LSM303DLH magnetometer however publishes its X/Y/Z output as a pair of big-endian bytes (the H register sits at the lower address, 0x03/0x05/0x07, and the L register immediately after), and its channel specs in st_magn_core.c correctly declare IIO_BE -- but read_axis_data() ignored that and decoded as little-endian, swapping the high and low bytes of every magnetometer sample. The LSM303DLHC and LSM303DLM share the same st_magn_16bit_channels (IIO_BE) and were therefore byte-swapped by the same bug; users of those parts will see different in_magn_*_raw values after this fix lands. The bug is most visible on a stationary chip: in earth's field the true X reading is small and the high byte sits at 0x00, so swapping the bytes pins sysfs X at exactly the low byte's pattern (e.g. 0x00F0 = 240). Y and Z still appear "to vary" because their magnitudes are larger and the noise in the low byte produces big swings in the swapped high byte: before (LSM303DLH flat, sysfs in_magn_*_raw): X=240 (stuck), Y= 12032..23296, Z=-16128..-9728 after (direct i2c-dev big-endian decode, same chip same orientation): X≈-4096, Y≈210, Z≈80 (sensible values reflecting earth's ambient field at low gauss range) Fix read_axis_data() to dispatch on ch->scan_type.endianness and call get_unaligned_be16() / get_unaligned_be24() when the channel declares IIO_BE. Existing IIO_LE consumers (st_accel, st_gyro, st_pressure, st_lsm6dsx and others) are unaffected because their channel specs already declare IIO_LE and the LE path is unchanged. While restructuring the branches, replace the previously implicit silent-success-with-uninitialised-*data fall-through for byte_for_channel outside 1..3 with an explicit return -EINVAL. No in-tree ST sensor publishes such a channel, but the new behaviour is strictly safer than handing userspace garbage. Fixes: 23491b513bcd ("iio:common: Add STMicroelectronics common library") Cc: stable@vger.kernel.org Assisted-by: Claude:claude-opus-4-7 sparse smatch clang-analyzer coccinelle checkpatch Assisted-by: Sashiko:claude-opus-4-7 Signed-off-by: Herman van Hazendonk Reviewed-by: Andy Shevchenko Signed-off-by: Jonathan Cameron Signed-off-by: Greg Kroah-Hartman --- drivers/iio/common/st_sensors/st_sensors_core.c | 23 +++++++++++++++++------ 1 file changed, 17 insertions(+), 6 deletions(-) --- a/drivers/iio/common/st_sensors/st_sensors_core.c +++ b/drivers/iio/common/st_sensors/st_sensors_core.c @@ -498,6 +498,7 @@ static int st_sensors_read_axis_data(str u8 *outdata; struct st_sensor_data *sdata = iio_priv(indio_dev); unsigned int byte_for_channel; + u32 tmp; byte_for_channel = DIV_ROUND_UP(ch->scan_type.realbits + ch->scan_type.shift, 8); @@ -510,12 +511,22 @@ static int st_sensors_read_axis_data(str if (err < 0) goto st_sensors_free_memory; - if (byte_for_channel == 1) - *data = (s8)*outdata; - else if (byte_for_channel == 2) - *data = (s16)get_unaligned_le16(outdata); - else if (byte_for_channel == 3) - *data = (s32)sign_extend32(get_unaligned_le24(outdata), 23); + if (byte_for_channel == 1) { + tmp = *outdata; + } else if (byte_for_channel == 2) { + if (ch->scan_type.endianness == IIO_BE) + tmp = get_unaligned_be16(outdata); + else + tmp = get_unaligned_le16(outdata); + } else if (byte_for_channel == 3) { + if (ch->scan_type.endianness == IIO_BE) + tmp = get_unaligned_be24(outdata); + else + tmp = get_unaligned_le24(outdata); + } else { + return -EINVAL; + } + *data = sign_extend32(tmp, BYTES_TO_BITS(byte_for_channel) - 1); st_sensors_free_memory: kfree(outdata);