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 CF4B53B0ADE; Thu, 16 Jul 2026 14:23:04 +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=1784211786; cv=none; b=WoWJ8uKloOO4nt1v891ARni8yXslzPOHk6ZuVCh1i4O1Q3/n2/dxOz6sJ6BX/UcdalVaBX3rbxU38E+GFywmxZHR6ssrCn8886RHdPxMkwBV9WNnGPjmIXd4ULl8jo1aqIILd4hj8ZTX3Q/clzyEEMDzCiZSyT7qBXglLml8zJY= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784211786; c=relaxed/simple; bh=rofNE/oUlscFFzmIGQWIVeWOn5OiyjEz7ZKrwb61pPE=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=AgDS4SVx0OwfdXo7orVuPLivz4cxIjpqEnj585n/We3t+0ul0Ycq9nQHurPOeVNx5h82ztUF4rAD8qtzCd8z/L2kGL3Pnq069DQ9tgL87y3T7KLIXxnffPZf44OH6TiWqc/hgaKbjjZ9AZMsNh8UEhbXCei1hvlBJipMrS8E3Oc= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=XdI+11Fv; 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="XdI+11Fv" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 406261F000E9; Thu, 16 Jul 2026 14:23:04 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1784211784; bh=vg1aNoYga5b4JCuf/Ync6CcYkec+0HyomkIlNDy+7Ig=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=XdI+11FvvVmbAtUJwETgoHNP5qpgl7n83hDpF+zXd3SVuVw+/c3TbyVbUUahB97gO JRpSqcvEHmdBEafv6rC78fMH2KSyvD2vGE1PeMiWgqP+spiWwyQRqTra+45hJ6WSEn oVY9bbZ+GKfxMUnlnUD+Yofv6YU5LQHUueH8JXAo= 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 6.12 052/349] iio: common: st_sensors: honour channel endianness in read_axis_data Date: Thu, 16 Jul 2026 15:29:46 +0200 Message-ID: <20260716133034.488002420@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260716133033.287196923@linuxfoundation.org> References: <20260716133033.287196923@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 6.12-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);