serial: sh-sci: Fix crash in rx_timer_fn() on PIO fallback

[ 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@glider.be>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/drivers/tty/serial/sh-sci.c b/drivers/tty/serial/sh-sci.c
index 5550289e6678b87e71cdb8bca2930c719c27f94e..9e1a6af23ca2b1257ebcaab83cb80a2c7935ded3 100644 (file)
--- 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)