Hi Greg, > -----Original Message----- > From: Greg KH <gregkh@xxxxxxxxxxxxxxxxxxx> > Sent: 2021年4月26日 16:09 > To: Sherry Sun <sherry.sun@xxxxxxx> > Cc: jirislaby@xxxxxxxxxx; linux-serial@xxxxxxxxxxxxxxx; linux- > kernel@xxxxxxxxxxxxxxx; dl-linux-imx <linux-imx@xxxxxxx> > Subject: Re: [PATCH 1/2] tty: serial: fsl_lpuart: fix the potential bug of division > or modulo by zero > > On Mon, Apr 26, 2021 at 03:49:34PM +0800, Sherry Sun wrote: > > This issue is reported by Coverity Check. > > In lpuart32_console_get_options, division or modulo by zero may > > results in undefined behavior. > > > > Signed-off-by: Sherry Sun <sherry.sun@xxxxxxx> > > --- > > drivers/tty/serial/fsl_lpuart.c | 3 +++ > > 1 file changed, 3 insertions(+) > > > > diff --git a/drivers/tty/serial/fsl_lpuart.c > > b/drivers/tty/serial/fsl_lpuart.c index 794035041744..777d54b593f8 > > 100644 > > --- a/drivers/tty/serial/fsl_lpuart.c > > +++ b/drivers/tty/serial/fsl_lpuart.c > > @@ -2414,6 +2414,9 @@ lpuart32_console_get_options(struct lpuart_port > > *sport, int *baud, > > > > bd = lpuart32_read(&sport->port, UARTBAUD); > > bd &= UARTBAUD_SBR_MASK; > > + if (!bd) > > + return; > > How can this ever happen? > > Not to say this is a bad check, but it feels like this can't really happen in real > life, what code patch could create this result? > > And have you tested this on real hardware? > Thanks for the reviewing, yes, I have tested the patchset on the real hardware. Seems the coverity check is static scan, so cannot judge if UARTBAUD Register will be zero. I just found below statement in the uart reference manual: "When SBR is 1 - 8191, the baud rate equals "baud clock / ((OSR+1) × SBR)"." Since I am not familiar with uart, do you mean that the value of UARTBAUD Register will never be zero, so this case will not happen in real word? If yes, I will drop this patch. Best regards Sherry > thanks, > > greg k-h
