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Subject[PATCH 4.12 010/196] NFC: fix broken device allocation
Date
4.12-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Johan Hovold <johan@kernel.org>

commit 20777bc57c346b6994f465e0d8261a7fbf213a09 upstream.

Commit 7eda8b8e9677 ("NFC: Use IDR library to assing NFC devices IDs")
moved device-id allocation and struct-device initialisation from
nfc_allocate_device() to nfc_register_device().

This broke just about every nfc-device-registration error path, which
continue to call nfc_free_device() that tries to put the device
reference of the now uninitialised (but zeroed) struct device:

kobject: '(null)' (ce316420): is not initialized, yet kobject_put() is being called.

The late struct-device initialisation also meant that various work
queues whose names are derived from the nfc device name were also
misnamed:

421 root 0 SW< [(null)_nci_cmd_]
422 root 0 SW< [(null)_nci_rx_w]
423 root 0 SW< [(null)_nci_tx_w]

Move the id-allocation and struct-device initialisation back to
nfc_allocate_device() and fix up the single call site which did not use
nfc_free_device() in its error path.

Fixes: 7eda8b8e9677 ("NFC: Use IDR library to assing NFC devices IDs")
Cc: Samuel Ortiz <sameo@linux.intel.com>
Signed-off-by: Johan Hovold <johan@kernel.org>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
net/nfc/core.c | 31 ++++++++++++++++++-------------
net/nfc/nci/core.c | 3 +--
2 files changed, 19 insertions(+), 15 deletions(-)

--- a/net/nfc/core.c
+++ b/net/nfc/core.c
@@ -982,6 +982,8 @@ static void nfc_release(struct device *d
kfree(se);
}

+ ida_simple_remove(&nfc_index_ida, dev->idx);
+
kfree(dev);
}

@@ -1056,6 +1058,7 @@ struct nfc_dev *nfc_allocate_device(stru
int tx_headroom, int tx_tailroom)
{
struct nfc_dev *dev;
+ int rc;

if (!ops->start_poll || !ops->stop_poll || !ops->activate_target ||
!ops->deactivate_target || !ops->im_transceive)
@@ -1068,6 +1071,15 @@ struct nfc_dev *nfc_allocate_device(stru
if (!dev)
return NULL;

+ rc = ida_simple_get(&nfc_index_ida, 0, 0, GFP_KERNEL);
+ if (rc < 0)
+ goto err_free_dev;
+ dev->idx = rc;
+
+ dev->dev.class = &nfc_class;
+ dev_set_name(&dev->dev, "nfc%d", dev->idx);
+ device_initialize(&dev->dev);
+
dev->ops = ops;
dev->supported_protocols = supported_protocols;
dev->tx_headroom = tx_headroom;
@@ -1090,6 +1102,11 @@ struct nfc_dev *nfc_allocate_device(stru
}

return dev;
+
+err_free_dev:
+ kfree(dev);
+
+ return ERR_PTR(rc);
}
EXPORT_SYMBOL(nfc_allocate_device);

@@ -1104,14 +1121,6 @@ int nfc_register_device(struct nfc_dev *

pr_debug("dev_name=%s\n", dev_name(&dev->dev));

- dev->idx = ida_simple_get(&nfc_index_ida, 0, 0, GFP_KERNEL);
- if (dev->idx < 0)
- return dev->idx;
-
- dev->dev.class = &nfc_class;
- dev_set_name(&dev->dev, "nfc%d", dev->idx);
- device_initialize(&dev->dev);
-
mutex_lock(&nfc_devlist_mutex);
nfc_devlist_generation++;
rc = device_add(&dev->dev);
@@ -1149,12 +1158,10 @@ EXPORT_SYMBOL(nfc_register_device);
*/
void nfc_unregister_device(struct nfc_dev *dev)
{
- int rc, id;
+ int rc;

pr_debug("dev_name=%s\n", dev_name(&dev->dev));

- id = dev->idx;
-
if (dev->rfkill) {
rfkill_unregister(dev->rfkill);
rfkill_destroy(dev->rfkill);
@@ -1179,8 +1186,6 @@ void nfc_unregister_device(struct nfc_de
nfc_devlist_generation++;
device_del(&dev->dev);
mutex_unlock(&nfc_devlist_mutex);
-
- ida_simple_remove(&nfc_index_ida, id);
}
EXPORT_SYMBOL(nfc_unregister_device);

--- a/net/nfc/nci/core.c
+++ b/net/nfc/nci/core.c
@@ -1173,8 +1173,7 @@ struct nci_dev *nci_allocate_device(stru
return ndev;

free_nfc:
- kfree(ndev->nfc_dev);
-
+ nfc_free_device(ndev->nfc_dev);
free_nci:
kfree(ndev);
return NULL;

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