[PATCH 4.19 122/321] serial: sh-sci: Fix crash in rx_timer_fn() on PIO fallback

[Greg Kroah-Hartman]

From: Geert Uytterhoeven <geert+renesas@xxxxxxxxx>

[ Upstream commit 2e948218b7c1262a3830823d6620eb227e3d4e3a ]

When falling back to PIO, active_rx must be set to a different value
than cookie_rx[i], else sci_dma_rx_find_active() will incorrectly find a
match, leading to a NULL pointer dereference in rx_timer_fn() later.

Use zero instead, which is the same value as after driver
initialization.

Signed-off-by: Geert Uytterhoeven <geert+renesas@xxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
 drivers/tty/serial/sh-sci.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/tty/serial/sh-sci.c b/drivers/tty/serial/sh-sci.c
index 5550289e6678b..9e1a6af23ca2b 100644
--- a/drivers/tty/serial/sh-sci.c
+++ b/drivers/tty/serial/sh-sci.c
@@ -1359,7 +1359,7 @@ fail:
 		dmaengine_terminate_async(chan);
 	for (i = 0; i < 2; i++)
 		s->cookie_rx[i] = -EINVAL;
-	s->active_rx = -EINVAL;
+	s->active_rx = 0;
 	s->chan_rx = NULL;
 	sci_start_rx(port);
 	if (!port_lock_held)
-- 
2.20.1