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serial: 8250_dma: Fix DMA Rx completion race

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commit 31352811e1 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@kontron.com>
Tested-by: Gilles BULOZ <gilles.buloz@kontron.com>
Fixes: 9ee4b83e51 ("serial: 8250: Add support for dmaengine")
Cc: stable@vger.kernel.org
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Link: https://lore.kernel.org/r/20230130114841.25749-2-ilpo.jarvinen@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Ilpo Järvinen 2023-01-30 13:48:40 +02:00 committed by Greg Kroah-Hartman
parent a5a171f61a
commit e30328f599
1 changed files with 13 additions and 1 deletions
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14
drivers/tty/serial/8250/8250_dma.c
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@ -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;
@ -134,7 +146,7 @@ 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);