FAILED: patch "[PATCH] iio:imu:st_lsm6dsx: check st_lsm6dsx_shub_read_output return" failed to apply to 5.4-stable tree

[<gregkh@linuxfoundation.org>]

The patch below does not apply to the 5.4-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable@vger.kernel.org>.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From f71e41e23e129640f620b65fc362a6da02580310 Mon Sep 17 00:00:00 2001
From: Tom Rix <trix@redhat.com>
Date: Sun, 9 Aug 2020 10:55:51 -0700
Subject: [PATCH] iio:imu:st_lsm6dsx: check st_lsm6dsx_shub_read_output return

Potential error return is not checked.  This can lead to use
of undefined data.

Detected by clang static analysis.

st_lsm6dsx_shub.c:540:8: warning: Assigned value is garbage or undefined
        *val = (s16)le16_to_cpu(*((__le16 *)data));
             ^ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Fixes: c91c1c844ebd ("iio: imu: st_lsm6dsx: add i2c embedded controller support")
Signed-off-by: Tom Rix <trix@redhat.com
Cc: <Stable@vger.kernel.org>
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Link: https://lore.kernel.org/r/20200809175551.6794-1-trix@redhat.com
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

diff --git a/drivers/iio/imu/st_lsm6dsx/st_lsm6dsx_shub.c b/drivers/iio/imu/st_lsm6dsx/st_lsm6dsx_shub.c
index ed83471dc7dd..8c8d8870ca07 100644
--- a/drivers/iio/imu/st_lsm6dsx/st_lsm6dsx_shub.c
+++ b/drivers/iio/imu/st_lsm6dsx/st_lsm6dsx_shub.c
@@ -313,6 +313,8 @@ st_lsm6dsx_shub_read(struct st_lsm6dsx_sensor *sensor, u8 addr,
 
 	err = st_lsm6dsx_shub_read_output(hw, data,
 					  len & ST_LS6DSX_READ_OP_MASK);
+	if (err < 0)
+		return err;
 
 	st_lsm6dsx_shub_master_enable(sensor, false);