Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit 71d6b277 authored by Ilpo Järvinen's avatar Ilpo Järvinen Committed by Greg Kroah-Hartman
Browse files

serial: 8250_dma: Fix DMA Rx completion race 



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: default avatarGilles BULOZ <gilles.buloz@kontron.com>
Tested-by: default avatarGilles BULOZ <gilles.buloz@kontron.com>
Fixes: 9ee4b83e ("serial: 8250: Add support for dmaengine")
Cc: stable@vger.kernel.org
Signed-off-by: default avatarIlpo Järvinen <ilpo.jarvinen@linux.intel.com>
Link: https://lore.kernel.org/r/20230130114841.25749-2-ilpo.jarvinen@linux.intel.com


Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent ec5b4ca3

drivers/tty/serial/8250/8250_dma.c

+13 −1
Original line number Diff line number Diff line
@@ -59,6 +59,18 @@ static void __dma_rx_complete(void *param) 
	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;
@@ -121,7 +133,7 @@ int serial8250_rx_dma(struct uart_8250_port *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);