From: Sherry Sun Date: Tue, 27 Apr 2021 02:12:26 +0000 (+0800) Subject: tty: serial: fsl_lpuart: fix the potential risk of division or modulo by zero X-Git-Tag: v4.4.276~47 X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=80ba909abe14f0fa64716509f4f83537bb06f21e;p=thirdparty%2Fkernel%2Fstable.git tty: serial: fsl_lpuart: fix the potential risk of division or modulo by zero [ Upstream commit fcb10ee27fb91b25b68d7745db9817ecea9f1038 ] We should be very careful about the register values that will be used for division or modulo operations, althrough the possibility that the UARTBAUD register value is zero is very low, but we had better to deal with the "bad data" of hardware in advance to avoid division or modulo by zero leading to undefined kernel behavior. Signed-off-by: Sherry Sun Link: https://lore.kernel.org/r/20210427021226.27468-1-sherry.sun@nxp.com Signed-off-by: Greg Kroah-Hartman Signed-off-by: Sasha Levin --- diff --git a/drivers/tty/serial/fsl_lpuart.c b/drivers/tty/serial/fsl_lpuart.c index 1544a7cc76ff8..1319f3dd5b704 100644 --- a/drivers/tty/serial/fsl_lpuart.c +++ b/drivers/tty/serial/fsl_lpuart.c @@ -1681,6 +1681,9 @@ lpuart32_console_get_options(struct lpuart_port *sport, int *baud, bd = lpuart32_read(sport->port.membase + UARTBAUD); bd &= UARTBAUD_SBR_MASK; + if (!bd) + return; + sbr = bd; uartclk = clk_get_rate(sport->clk); /*