All of lore.kernel.org
 help / color / mirror / Atom feed
From: Sherry Sun <sherry.sun@nxp.com>
To: gregkh@linuxfoundation.org, jirislaby@kernel.org
Cc: linux-serial@vger.kernel.org, linux-kernel@vger.kernel.org,
	linux-imx@nxp.com
Subject: [PATCH V2] tty: serial: fsl_lpuart: fix the potential risk of division or modulo by zero
Date: Tue, 27 Apr 2021 10:12:26 +0800	[thread overview]
Message-ID: <20210427021226.27468-1-sherry.sun@nxp.com> (raw)

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@nxp.com>
---
V2: Amend commit message according to the review suggestions for better
understand the change. 
---
 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;
+
 	sbr = bd;
 	uartclk = lpuart_get_baud_clk_rate(sport);
 	/*
-- 
2.17.1


                 reply	other threads:[~2021-04-27  2:13 UTC|newest]

Thread overview: [no followups] expand[flat|nested]  mbox.gz  Atom feed

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20210427021226.27468-1-sherry.sun@nxp.com \
    --to=sherry.sun@nxp.com \
    --cc=gregkh@linuxfoundation.org \
    --cc=jirislaby@kernel.org \
    --cc=linux-imx@nxp.com \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-serial@vger.kernel.org \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body. 
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.