Patch "NFC: nfcmrvl: do not use device-managed resources" has been added to the 4.9-stable tree

This is a note to let you know that I've just added the patch titled

NFC: nfcmrvl: do not use device-managed resources

to the 4.9-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
nfc-nfcmrvl-do-not-use-device-managed-resources.patch
and it can be found in the queue-4.9 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Johan Hovold <[email protected]>
Date: Thu, 30 Mar 2017 12:15:37 +0200
Subject: NFC: nfcmrvl: do not use device-managed resources

From: Johan Hovold <[email protected]>

commit 0cbe40112f42cf5e008f9127f6cd5952ba3946c7 upstream.

This specifically fixes resource leaks in the registration error paths.

Device-managed resources is a bad fit for this driver as devices can be registered from the n_nci line discipline. Firstly, a tty may not even have a corresponding device (should it be part of a Unix98 pty) something which would lead to a NULL-pointer dereference when registering resources.

Secondly, if the tty has a class device, its lifetime exceeds that of the line discipline, which means that resources would leak every time the line discipline is closed (or if registration fails).

Currently, the devres interface was only being used to request a reset gpio despite the fact that it was already explicitly freed in nfcmrvl_nci_unregister_dev() (along with the private data), something which also prevented the resource leak at close.

Note that the driver treats gpio number 0 as invalid despite it being perfectly valid. This will be addressed in a follow-up patch.

---
 drivers/nfc/nfcmrvl/main.c |   19 +++++++++++--------
 1 file changed, 11 insertions(+), 8 deletions(-)

@@ -124,12 +124,13 @@ struct nfcmrvl_private *nfcmrvl_nci_regi
 	memcpy(&priv->config, pdata, sizeof(*pdata));
 
 	if (priv->config.reset_n_io) {
-		rc = devm_gpio_request_one(dev,
-					   priv->config.reset_n_io,
-					   GPIOF_OUT_INIT_LOW,
-					   "nfcmrvl_reset_n");
-		if (rc < 0)
+		rc = gpio_request_one(priv->config.reset_n_io,
+				      GPIOF_OUT_INIT_LOW,
+				      "nfcmrvl_reset_n");
+		if (rc < 0) {
+			priv->config.reset_n_io = 0;
 			nfc_err(dev, "failed to request reset_n io\n");
+		}
 	}
 
 	if (phy == NFCMRVL_PHY_SPI) {

@@ -154,7 +155,7 @@ struct nfcmrvl_private *nfcmrvl_nci_regi
 	if (!priv->ndev) {
 		nfc_err(dev, "nci_allocate_device failed\n");
 		rc = -ENOMEM;
-		goto error;
+		goto error_free_gpio;
 	}
 
 	nci_set_drvdata(priv->ndev, priv);

@@ -179,7 +180,9 @@ struct nfcmrvl_private *nfcmrvl_nci_regi
 
 error_free_dev:
 	nci_free_device(priv->ndev);
-error:
+error_free_gpio:
+	if (priv->config.reset_n_io)
+		gpio_free(priv->config.reset_n_io);
 	kfree(priv);
 	return ERR_PTR(rc);
 }

@@ -195,7 +198,7 @@ void nfcmrvl_nci_unregister_dev(struct n
 	nfcmrvl_fw_dnld_deinit(priv);
 
 	if (priv->config.reset_n_io)
-		devm_gpio_free(priv->dev, priv->config.reset_n_io);
+		gpio_free(priv->config.reset_n_io);
 
 	nci_unregister_device(ndev);
 	nci_free_device(ndev);

Patches currently in stable-queue which might be from [email protected] are

queue-4.9/nfc-nfcmrvl-use-nfc-device-for-firmware-download.patch queue-4.9/nfc-nfcmrvl-fix-firmware-management-initialisation.patch queue-4.9/nfc-nfcmrvl-do-not-use-device-managed-resources.patch queue-4.9/thermal-max77620-fix-device-node-reference-imbalance.patch queue-4.9/nfc-nfcmrvl_uart-add-missing-tty-device-sanity-check.patch queue-4.9/nfc-fix-broken-device-allocation.patch