From: Johan Hovold <johan@kernel.org>
To: Johan Hovold <johan@kernel.org>
Cc: linux-usb@vger.kernel.org, linux-kernel@vger.kernel.org,
stable@vger.kernel.org, Maksim Salau <maksim.salau@gmail.com>
Subject: [PATCH] USB: serial: upd78f0730: fix NULL-deref on hangup
Date: Mon, 19 Oct 2026 14:34:12 +0200 [thread overview]
Message-ID: <20261019123412.2007715-1-johan@kernel.org> (raw)
The port tty pointer is cleared on hangup before deasserting the modem
control signals and should not be used in the dtr_rts() callback.
Factor out a new upd78f0730_port_tiocmset() helper that can be used in
upd78f0730_dtr_rts() to avoid dereferencing a NULL-pointer on hangup
(e.g. on disconnect).
This issue was flagged by an LLM.
Fixes: ea534e0b4047 ("USB: serial: add uPD78F0730 USB to Serial Adaptor Driver")
Cc: stable@vger.kernel.org # 4.11
Cc: Maksim Salau <maksim.salau@gmail.com>
Assisted-by: LLM
Signed-off-by: Johan Hovold <johan@kernel.org>
---
drivers/usb/serial/upd78f0730.c | 13 +++++++++----
1 file changed, 9 insertions(+), 4 deletions(-)
diff --git a/drivers/usb/serial/upd78f0730.c b/drivers/usb/serial/upd78f0730.c
index 78c4d3c19a8e..f2189b994ed7 100644
--- a/drivers/usb/serial/upd78f0730.c
+++ b/drivers/usb/serial/upd78f0730.c
@@ -201,10 +201,9 @@ static int upd78f0730_tiocmget(struct tty_struct *tty)
return res;
}
-static int upd78f0730_tiocmset(struct tty_struct *tty,
+static int upd78f0730_port_tiocmset(struct usb_serial_port *port,
unsigned int set, unsigned int clear)
{
- struct usb_serial_port *port = tty->driver_data;
struct upd78f0730_port_private *private;
struct upd78f0730_set_dtr_rts request;
struct device *dev = &port->dev;
@@ -238,6 +237,13 @@ static int upd78f0730_tiocmset(struct tty_struct *tty,
return res;
}
+static int upd78f0730_tiocmset(struct tty_struct *tty, unsigned int set, unsigned int clear)
+{
+ struct usb_serial_port *port = tty->driver_data;
+
+ return upd78f0730_port_tiocmset(port, set, clear);
+}
+
static int upd78f0730_break_ctl(struct tty_struct *tty, int break_state)
{
struct upd78f0730_port_private *private;
@@ -267,7 +273,6 @@ static int upd78f0730_break_ctl(struct tty_struct *tty, int break_state)
static void upd78f0730_dtr_rts(struct usb_serial_port *port, int on)
{
- struct tty_struct *tty = port->port.tty;
unsigned int set = 0;
unsigned int clear = 0;
@@ -276,7 +281,7 @@ static void upd78f0730_dtr_rts(struct usb_serial_port *port, int on)
else
clear = TIOCM_DTR | TIOCM_RTS;
- upd78f0730_tiocmset(tty, set, clear);
+ upd78f0730_port_tiocmset(port, set, clear);
}
static speed_t upd78f0730_get_baud_rate(struct tty_struct *tty)
--
2.55.0
reply other threads:[~2026-10-19 12:34 UTC|newest]
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