This is a note to let you know that I've just added the patch titled
tty: serial: fsl_lpuart: fix the potential risk of division or modulo by zero
to the 5.13-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
tty-serial-fsl_lpuart-fix-the-potential-risk-of-divi.patch
and it can be found in the queue-5.13 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 2c0d223fcd59e5b30a91b01d10886fc657a6a56b
Author: Sherry Sun <sherry.sun@xxxxxxx>
Date: Tue Apr 27 10:12:26 2021 +0800
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 <sherry.sun@xxxxxxx>
Link: https://lore.kernel.org/r/20210427021226.27468-1-sherry.sun@xxxxxxx
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/drivers/tty/serial/fsl_lpuart.c b/drivers/tty/serial/fsl_lpuart.c
index 9c78e43e669d..4cad2ac00e9f 100644
--- a/drivers/tty/serial/fsl_lpuart.c
+++ b/drivers/tty/serial/fsl_lpuart.c
@@ -2404,6 +2404,9 @@ lpuart32_console_get_options(struct lpuart_port *sport, int *baud,
bd = lpuart32_read(&sport->port, UARTBAUD);
bd &= UARTBAUD_SBR_MASK;
+ if (!bd)
+ return;
+
sbr = bd;
uartclk = lpuart_get_baud_clk_rate(sport);
/*
