NFC: nfcmrvl: fix gpio-handling regression

Fix two reset-gpio sanity checks which were never converted to use
gpio_is_valid(), and make sure to use -EINVAL to indicate a missing
reset line also for the UART-driver module parameter and for the USB
driver.

This specifically prevents the UART and USB drivers from incidentally
trying to request and use gpio 0, and also avoids triggering a WARN() in
gpio_to_desc() during probe when no valid reset line has been specified.

Fixes: e33a3f84f88f ("NFC: nfcmrvl: allow gpio 0 for reset signalling")
Reported-by: syzbot+cf35b76f35e068a1107f@syzkaller.appspotmail.com
Tested-by: syzbot+cf35b76f35e068a1107f@syzkaller.appspotmail.com
Signed-off-by: Johan Hovold <johan@kernel.org>

3 files changed, 5 insertions, 4 deletions

diff --git a/drivers/nfc/nfcmrvl/main.c b/drivers/nfc/nfcmrvl/main.c
index e65d027b91fa..529be35ac178 100644
--- a/drivers/nfc/nfcmrvl/main.c
+++ b/drivers/nfc/nfcmrvl/main.c
@@ -244,7 +244,7 @@ void nfcmrvl_chip_reset(struct nfcmrvl_private *priv)
         /* Reset possible fault of previous session */
         clear_bit(NFCMRVL_PHY_ERROR, &priv->flags);
 
-        if (priv->config.reset_n_io) {
+        if (gpio_is_valid(priv->config.reset_n_io)) {
                 nfc_info(priv->dev, "reset the chip\n");
                 gpio_set_value(priv->config.reset_n_io, 0);
                 usleep_range(5000, 10000);
@@ -255,7 +255,7 @@ void nfcmrvl_chip_reset(struct nfcmrvl_private *priv)
 
 void nfcmrvl_chip_halt(struct nfcmrvl_private *priv)
 {
-        if (priv->config.reset_n_io)
+        if (gpio_is_valid(priv->config.reset_n_io))
                 gpio_set_value(priv->config.reset_n_io, 0);
 }
 
diff --git a/drivers/nfc/nfcmrvl/uart.c b/drivers/nfc/nfcmrvl/uart.c
index 9a22056e8d9e..e5a622ce4b95 100644
--- a/drivers/nfc/nfcmrvl/uart.c
+++ b/drivers/nfc/nfcmrvl/uart.c
@@ -26,7 +26,7 @@
 static unsigned int hci_muxed;
 static unsigned int flow_control;
 static unsigned int break_control;
-static unsigned int reset_n_io;
+static int reset_n_io = -EINVAL;
 
 /*
 ** NFCMRVL NCI OPS
@@ -231,5 +231,5 @@ MODULE_PARM_DESC(break_control, "Tell if UART driver must drive break signal.");
 module_param(hci_muxed, uint, 0);
 MODULE_PARM_DESC(hci_muxed, "Tell if transport is muxed in HCI one.");
 
-module_param(reset_n_io, uint, 0);
+module_param(reset_n_io, int, 0);
 MODULE_PARM_DESC(reset_n_io, "GPIO that is wired to RESET_N signal.");
diff --git a/drivers/nfc/nfcmrvl/usb.c b/drivers/nfc/nfcmrvl/usb.c
index 945cc903d8f1..888e298f610b 100644
--- a/drivers/nfc/nfcmrvl/usb.c
+++ b/drivers/nfc/nfcmrvl/usb.c
@@ -305,6 +305,7 @@ static int nfcmrvl_probe(struct usb_interface *intf,
 
         /* No configuration for USB */
         memset(&config, 0, sizeof(config));
+        config.reset_n_io = -EINVAL;
 
         nfc_info(&udev->dev, "intf %p id %p\n", intf, id);