[PATCH net v5 1/2] nfc: nfcmrvl: publish UART state before registration

[Shubham Antil <shubham@octane.security>]

nfcmrvl_nci_uart_open() does not publish nu->drv_data and nu->ndev until
nfcmrvl_nci_register_dev() returns.  The registration call exposes the NCI
device first, so an early transmit can reach the UART callbacks while those
back-pointers are not initialized.

Add callbacks which publish the UART back-pointers before
nci_register_device() and withdraw them if registration fails.  Halt the
controller before exposing the device as well.

The ordering issue was found during an LLM-assisted source audit and
reproduced using a pty-backed NCI UART under KASAN.

Fixes: e097dc624f78 ("NFC: nfcmrvl: add UART driver")
Cc: stable@vger.kernel.org
Assisted-by: LLM (OpenAI Codex, gpt-5.6-sol)
Signed-off-by: Shubham Antil <shubham@octane.security>
---
 drivers/nfc/nfcmrvl/main.c    | 11 ++++++++---
 drivers/nfc/nfcmrvl/nfcmrvl.h |  2 ++
 drivers/nfc/nfcmrvl/uart.c    | 24 +++++++++++++++++++-----
 3 files changed, 29 insertions(+), 8 deletions(-)

diff --git a/drivers/nfc/nfcmrvl/main.c b/drivers/nfc/nfcmrvl/main.c
index 6efa83219117..3d26a54ef51b 100644
--- a/drivers/nfc/nfcmrvl/main.c
+++ b/drivers/nfc/nfcmrvl/main.c
@@ -154,20 +154,25 @@ struct nfcmrvl_private *nfcmrvl_nci_register_dev(enum nfcmrvl_phy phy,
 
 	nci_set_drvdata(priv->ndev, priv);
 
+	/* Ensure that controller is powered off before exposing the device. */
+	nfcmrvl_chip_halt(priv);
+
+	if (priv->if_ops->nci_ready)
+		priv->if_ops->nci_ready(priv);
+
 	rc = nci_register_device(priv->ndev);
 	if (rc) {
 		nfc_err(dev, "nci_register_device failed %d\n", rc);
 		goto error_fw_dnld_deinit;
 	}
 
-	/* Ensure that controller is powered off */
-	nfcmrvl_chip_halt(priv);
-
 	nfc_info(dev, "registered with nci successfully\n");
 	return priv;
 
 error_fw_dnld_deinit:
 	nfcmrvl_fw_dnld_deinit(priv);
+	if (priv->if_ops->nci_unready)
+		priv->if_ops->nci_unready(priv);
 error_free_dev:
 	nci_free_device(priv->ndev);
 error_free:
diff --git a/drivers/nfc/nfcmrvl/nfcmrvl.h b/drivers/nfc/nfcmrvl/nfcmrvl.h
index 62fa77d587b2..66f8cc06e2d5 100644
--- a/drivers/nfc/nfcmrvl/nfcmrvl.h
+++ b/drivers/nfc/nfcmrvl/nfcmrvl.h
@@ -112,6 +112,8 @@ struct nfcmrvl_if_ops {
 	int (*nci_open) (struct nfcmrvl_private *priv);
 	int (*nci_close) (struct nfcmrvl_private *priv);
 	int (*nci_send) (struct nfcmrvl_private *priv, struct sk_buff *skb);
+	void (*nci_ready)(struct nfcmrvl_private *priv);
+	void (*nci_unready)(struct nfcmrvl_private *priv);
 	void (*nci_update_config)(struct nfcmrvl_private *priv,
 				  const void *param);
 };
diff --git a/drivers/nfc/nfcmrvl/uart.c b/drivers/nfc/nfcmrvl/uart.c
index 9aedd168759c..d688071f4b26 100644
--- a/drivers/nfc/nfcmrvl/uart.c
+++ b/drivers/nfc/nfcmrvl/uart.c
@@ -44,6 +44,23 @@ static int nfcmrvl_uart_nci_send(struct nfcmrvl_private *priv,
 	return nu->ops.send(nu, skb);
 }
 
+static void nfcmrvl_uart_nci_ready(struct nfcmrvl_private *priv)
+{
+	struct nci_uart *nu = priv->drv_data;
+
+	priv->support_fw_dnld = true;
+	nu->drv_data = priv;
+	nu->ndev = priv->ndev;
+}
+
+static void nfcmrvl_uart_nci_unready(struct nfcmrvl_private *priv)
+{
+	struct nci_uart *nu = priv->drv_data;
+
+	nu->drv_data = NULL;
+	nu->ndev = NULL;
+}
+
 static void nfcmrvl_uart_nci_update_config(struct nfcmrvl_private *priv,
 					   const void *param)
 {
@@ -58,6 +75,8 @@ static const struct nfcmrvl_if_ops uart_ops = {
 	.nci_open = nfcmrvl_uart_nci_open,
 	.nci_close = nfcmrvl_uart_nci_close,
 	.nci_send = nfcmrvl_uart_nci_send,
+	.nci_ready = nfcmrvl_uart_nci_ready,
+	.nci_unready = nfcmrvl_uart_nci_unready,
 	.nci_update_config = nfcmrvl_uart_nci_update_config
 };
 
@@ -136,11 +155,6 @@ static int nfcmrvl_nci_uart_open(struct nci_uart *nu)
 	if (IS_ERR(priv))
 		return PTR_ERR(priv);
 
-	priv->support_fw_dnld = true;
-
-	nu->drv_data = priv;
-	nu->ndev = priv->ndev;
-
 	return 0;
 }
 
-- 
2.43.0