linux-kernel - [PATCH v2 3/8] NFC: nfcmrvl: do not use device-managed resources

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Date:   Thu, 30 Mar 2017 12:15:37 +0200
From:   Johan Hovold <johan@...nel.org>
To:     Lauro Ramos Venancio <lauro.venancio@...nbossa.org>,
        Aloisio Almeida Jr <aloisio.almeida@...nbossa.org>,
        Samuel Ortiz <sameo@...ux.intel.com>
Cc:     linux-wireless@...r.kernel.org, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org, Johan Hovold <johan@...nel.org>,
        stable <stable@...r.kernel.org>,
        Vincent Cuissard <cuissard@...vell.com>
Subject: [PATCH v2 3/8] NFC: nfcmrvl: do not use device-managed resources

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.

Fixes: b2fe288eac72 ("NFC: nfcmrvl: free reset gpio")
Fixes: 4a2b947f56b3 ("NFC: nfcmrvl: add chip reset management")
Cc: stable <stable@...r.kernel.org>     # 4.2: b2fe288eac72
Cc: Vincent Cuissard <cuissard@...vell.com>
Signed-off-by: Johan Hovold <johan@...nel.org>
---
 drivers/nfc/nfcmrvl/main.c | 19 +++++++++++--------
 1 file changed, 11 insertions(+), 8 deletions(-)

diff --git a/drivers/nfc/nfcmrvl/main.c b/drivers/nfc/nfcmrvl/main.c
index 51c8240a1672..3e3fc9588f10 100644
--- a/drivers/nfc/nfcmrvl/main.c
+++ b/drivers/nfc/nfcmrvl/main.c
@@ -124,12 +124,13 @@ struct nfcmrvl_private *nfcmrvl_nci_register_dev(enum nfcmrvl_phy phy,
 	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_register_dev(enum nfcmrvl_phy phy,
 	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_register_dev(enum nfcmrvl_phy phy,
 
 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 nfcmrvl_private *priv)
 	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);
-- 
2.12.2