On Wed, Jun 18, 2025 at 09:36:50AM +0200, Krzysztof Kozlowski wrote:

Setting tty->disc_data before opening the NCI device means we need to clean it up on error paths. This also opens some short window if device starts sending data, even before NCIUARTSETDRIVER IOCTL succeeded (broken hardware?). Close the window by exposing tty->disc_data only on the success path, when opening of the NCI device and try_module_get() succeeds.

The code differs in error path in one aspect: tty->disc_data won't be ever assigned thus NULL-ified. This however should not be relevant difference, because of "tty->disc_data=NULL" in nci_uart_tty_open().

Cc: Greg KH gregkh@linuxfoundation.org Cc: Linus Torvalds torvalds@linuxfoundation.org Cc: Paolo Abeni pabeni@redhat.com Cc: Jakub Kicinski kuba@kernel.org Fixes: 9961127d4bce ("NFC: nci: add generic uart support") Cc: stable@vger.kernel.org Signed-off-by: Krzysztof Kozlowski krzysztof.kozlowski@linaro.org

---

net/nfc/nci/uart.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/net/nfc/nci/uart.c b/net/nfc/nci/uart.c index ed1508a9e093..aab107727f18 100644 --- a/net/nfc/nci/uart.c +++ b/net/nfc/nci/uart.c @@ -119,22 +119,22 @@ static int nci_uart_set_driver(struct tty_struct *tty, unsigned int driver) memcpy(nu, nci_uart_drivers[driver], sizeof(struct nci_uart)); nu->tty = tty;

• tty->disc_data = nu; skb_queue_head_init(&nu->tx_q); INIT_WORK(&nu->write_work, nci_uart_write_work); spin_lock_init(&nu->rx_lock);

ret = nu->ops.open(nu); if (ret) {

• tty->disc_data = NULL;
  

  kfree(nu);

• return ret;
  

  } else if (!try_module_get(nu->owner)) { nu->ops.close(nu);

• tty->disc_data = NULL;
  

  kfree(nu); return -ENOENT; }
• return ret;

• tty->disc_data = nu;
• return 0;

}

Looks good, thanks for cleaning this up:

Reviewed-by: Greg Kroah-Hartman gregkh@linuxfoundation.org