This is a note to let you know that I've just added the patch titled
serial: 8250_dma: Fix DMA Rx completion race
to the 4.14-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:
serial-8250_dma-fix-dma-rx-completion-race.patch
and it can be found in the queue-4.14 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 31352811e13dc2313f101b890fd4b1ce760b5fe7 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Ilpo=20J=C3=A4rvinen?= <ilpo.jarvinen@xxxxxxxxxxxxxxx>
Date: Mon, 30 Jan 2023 13:48:40 +0200
Subject: serial: 8250_dma: Fix DMA Rx completion race
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From: Ilpo Järvinen <ilpo.jarvinen@xxxxxxxxxxxxxxx>
commit 31352811e13dc2313f101b890fd4b1ce760b5fe7 upstream.
__dma_rx_complete() is called from two places:
- Through the DMA completion callback dma_rx_complete()
- From serial8250_rx_dma_flush() after IIR_RLSI or IIR_RX_TIMEOUT
The former does not hold port's lock during __dma_rx_complete() which
allows these two to race and potentially insert the same data twice.
Extend port's lock coverage in dma_rx_complete() to prevent the race
and check if the DMA Rx is still pending completion before calling
into __dma_rx_complete().
Reported-by: Gilles BULOZ <gilles.buloz@xxxxxxxxxxx>
Tested-by: Gilles BULOZ <gilles.buloz@xxxxxxxxxxx>
Fixes: 9ee4b83e51f7 ("serial: 8250: Add support for dmaengine")
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@xxxxxxxxxxxxxxx>
Link: https://lore.kernel.org/r/20230130114841.25749-2-ilpo.jarvinen@xxxxxxxxxxxxxxx
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/tty/serial/8250/8250_dma.c | 14 +++++++++++++-
1 file changed, 13 insertions(+), 1 deletion(-)
--- a/drivers/tty/serial/8250/8250_dma.c
+++ b/drivers/tty/serial/8250/8250_dma.c
@@ -65,6 +65,18 @@ static void __dma_rx_complete(void *para
tty_flip_buffer_push(tty_port);
}
+static void dma_rx_complete(void *param)
+{
+ struct uart_8250_port *p = param;
+ struct uart_8250_dma *dma = p->dma;
+ unsigned long flags;
+
+ spin_lock_irqsave(&p->port.lock, flags);
+ if (dma->rx_running)
+ __dma_rx_complete(p);
+ spin_unlock_irqrestore(&p->port.lock, flags);
+}
+
int serial8250_tx_dma(struct uart_8250_port *p)
{
struct uart_8250_dma *dma = p->dma;
@@ -130,7 +142,7 @@ int serial8250_rx_dma(struct uart_8250_p
return -EBUSY;
dma->rx_running = 1;
- desc->callback = __dma_rx_complete;
+ desc->callback = dma_rx_complete;
desc->callback_param = p;
dma->rx_cookie = dmaengine_submit(desc);
Patches currently in stable-queue which might be from ilpo.jarvinen@xxxxxxxxxxxxxxx are
queue-4.14/serial-8250_dma-fix-dma-rx-rearm-race.patch
queue-4.14/serial-8250_dma-fix-dma-rx-completion-race.patch
