From e95571170159f0dcfc227a4c0875b30a7e38f097 Mon Sep 17 00:00:00 2001 From: Geert Uytterhoeven Date: Mon, 10 May 2021 14:07:55 +0200 Subject: [PATCH] serial: sh-sci: Fix off-by-one error in FIFO threshold register setting commit 2ea2e019c190ee3973ef7bcaf829d8762e56e635 upstream. The Receive FIFO Data Count Trigger field (RTRG[6:0]) in the Receive FIFO Data Count Trigger Register (HSRTRGR) of HSCIF can only hold values ranging from 0-127. As the FIFO size is equal to 128 on HSCIF, the user can write an out-of-range value, touching reserved bits. Fix this by limiting the trigger value to the FIFO size minus one. Reverse the order of the checks, to avoid rx_trig becoming zero if the FIFO size is one. Note that this change has no impact on other SCIF variants, as their maximum supported trigger value is lower than the FIFO size anyway, and the code below takes care of enforcing these limits. Fixes: a380ed461f66d1b8 ("serial: sh-sci: implement FIFO threshold register setting") Reported-by: Linh Phung Reviewed-by: Wolfram Sang Reviewed-by: Ulrich Hecht Signed-off-by: Geert Uytterhoeven Cc: stable Link: https://lore.kernel.org/r/5eff320aef92ffb33d00e57979fd3603bbb4a70f.1620648218.git.geert+renesas@glider.be Signed-off-by: Greg Kroah-Hartman --- drivers/tty/serial/sh-sci.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/drivers/tty/serial/sh-sci.c b/drivers/tty/serial/sh-sci.c index e1179e7..3b1aaa9 100644 --- a/drivers/tty/serial/sh-sci.c +++ b/drivers/tty/serial/sh-sci.c @@ -1023,10 +1023,10 @@ static int scif_set_rtrg(struct uart_port *port, int rx_trig) { unsigned int bits; + if (rx_trig >= port->fifosize) + rx_trig = port->fifosize - 1; if (rx_trig < 1) rx_trig = 1; - if (rx_trig >= port->fifosize) - rx_trig = port->fifosize; /* HSCIF can be set to an arbitrary level. */ if (sci_getreg(port, HSRTRGR)->size) { -- 2.7.4