From afc235a217360c6859068d2e37a4df305c4d1be2 Mon Sep 17 00:00:00 2001 From: Johan Hovold Date: Tue, 15 Sep 2026 14:40:11 +0200 Subject: [PATCH] USB: serial: ssu100: fix baud rate overflow The requested baud rate is incorrectly truncated to 16 bits so that line speeds above 65535 bps cannot be set. Use 32 bits for the rate and remainder while rejecting rates outside of [50,460800] to avoid having the divisor or remainder overflow. This issue was flagged by an LLM. Fixes: 52af95459939 ("USB: add USB serial ssu100 driver") Cc: stable@vger.kernel.org # 2.6.36 Cc: Bill Pemberton Assisted-by: LLM Signed-off-by: Johan Hovold --- drivers/usb/serial/ssu100.c | 18 ++++++++++++++++-- 1 file changed, 16 insertions(+), 2 deletions(-) diff --git a/drivers/usb/serial/ssu100.c b/drivers/usb/serial/ssu100.c index b0d51558b73c..8c5b9ef708b3 100644 --- a/drivers/usb/serial/ssu100.c +++ b/drivers/usb/serial/ssu100.c @@ -32,6 +32,7 @@ #define SERIAL_EVEN_PARITY (UART_LCR_PARITY | UART_LCR_EPAR) +#define MIN_BAUD_RATE 50 #define MAX_BAUD_RATE 460800 #define ATC_DISABLED 0x00 @@ -217,9 +218,10 @@ static void ssu100_set_termios(struct tty_struct *tty, { struct usb_device *dev = port->serial->dev; struct ktermios *termios = &tty->termios; - u16 baud, divisor, remainder; + speed_t baud, remainder; unsigned int cflag = termios->c_cflag; u16 urb_value = 0; /* will hold the new flags */ + u16 divisor; int result; if (cflag & PARENB) { @@ -235,6 +237,18 @@ static void ssu100_set_termios(struct tty_struct *tty, if (!baud) baud = 9600; + if (baud < MIN_BAUD_RATE || baud > MAX_BAUD_RATE) { + if (old_termios) + baud = tty_termios_baud_rate(old_termios); + else + baud = clamp(baud, MIN_BAUD_RATE, MAX_BAUD_RATE); + + tty_encode_baud_rate(tty, baud, baud); + + if (!baud) + baud = 9600; + } + dev_dbg(&port->dev, "%s - got baud = %d\n", __func__, baud); @@ -310,7 +324,7 @@ static int ssu100_open(struct tty_struct *tty, struct usb_serial_port *port) dev_dbg(&port->dev, "%s - set uart failed\n", __func__); if (tty) - ssu100_set_termios(tty, port, &tty->termios); + ssu100_set_termios(tty, port, NULL); return usb_serial_generic_open(tty, port); }