FAILED: patch "[PATCH] iio: core: check return value when calling dev_set_name()" failed to apply to 4.9-stable tree

[<gregkh@linuxfoundation.org>]

The patch below does not apply to the 4.9-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 fe6f45f6ba22d625a8500cbad0237c60dd3117ee Mon Sep 17 00:00:00 2001
From: Yang Yingliang <yangyingliang@huawei.com>
Date: Tue, 12 Oct 2021 14:36:24 +0800
Subject: [PATCH] iio: core: check return value when calling dev_set_name()

I got a null-ptr-deref report when doing fault injection test:

BUG: kernel NULL pointer dereference, address: 0000000000000000
RIP: 0010:strlen+0x0/0x20
Call Trace:
 start_creating+0x199/0x2f0
 debugfs_create_dir+0x25/0x430
 __iio_device_register+0x4da/0x1b40 [industrialio]
 __devm_iio_device_register+0x22/0x80 [industrialio]
 max1027_probe+0x639/0x860 [max1027]
 spi_probe+0x183/0x210
 really_probe+0x285/0xc30

If dev_set_name() fails, the dev_name() is null, check the return
value of dev_set_name() to avoid the null-ptr-deref.

Reported-by: Hulk Robot <hulkci@huawei.com>
Fixes: e553f182d55b ("staging: iio: core: Introduce debugfs support...")
Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>
Cc: <Stable@vger.kernel.org>
Link: https://lore.kernel.org/r/20211012063624.3167460-1-yangyingliang@huawei.com
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

diff --git a/drivers/iio/industrialio-core.c b/drivers/iio/industrialio-core.c
index 2dbb37e09b8c..48fda6a79076 100644
--- a/drivers/iio/industrialio-core.c
+++ b/drivers/iio/industrialio-core.c
@@ -1664,7 +1664,13 @@ struct iio_dev *iio_device_alloc(struct device *parent, int sizeof_priv)
 		kfree(iio_dev_opaque);
 		return NULL;
 	}
-	dev_set_name(&indio_dev->dev, "iio:device%d", iio_dev_opaque->id);
+
+	if (dev_set_name(&indio_dev->dev, "iio:device%d", iio_dev_opaque->id)) {
+		ida_simple_remove(&iio_ida, iio_dev_opaque->id);
+		kfree(iio_dev_opaque);
+		return NULL;
+	}
+
 	INIT_LIST_HEAD(&iio_dev_opaque->buffer_list);
 	INIT_LIST_HEAD(&iio_dev_opaque->ioctl_handlers);