When target_rate is big enough and not permitted in hardware, then i is looped to UART_DIV_MAX (0xFFFF), and i * max_rate will overflow (32b signed).
A fix is to quit the loop early enough, as soon as rate < i * min_rate as it means the rate is not permitted. This avoids arbitraty rates to be applied. Still in my hardware the max allowed rate (1500000) is aplied when a higher is requested. This seems a artifact of clk_round_rate which is not understood by me and independent of this fix. Might or might not be another bug. Signed-off-by: Nuno Goncalves <[email protected]> --- drivers/tty/serial/8250/8250_dw.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-) diff --git a/drivers/tty/serial/8250/8250_dw.c b/drivers/tty/serial/8250/8250_dw.c index 5bb0c42c88dd..a27ea916abbf 100644 --- a/drivers/tty/serial/8250/8250_dw.c +++ b/drivers/tty/serial/8250/8250_dw.c @@ -267,7 +267,13 @@ static void dw8250_set_termios(struct uart_port *p, struct ktermios *termios, for (i = 1; i <= UART_DIV_MAX; i++) { rate = clk_round_rate(d->clk, i * target_rate); - if (rate >= i * min_rate && rate <= i * max_rate) + + if (rate < i * min_rate) { + i = UART_DIV_MAX + 1; + break; + } + + if (rate <= i * max_rate) break; } if (i <= UART_DIV_MAX) { -- 2.11.0
