Re: [PATCH backport to 6.1 1/2] serial: 8250_dma: Fix DMA Rx completion race

[Greg Kroah-Hartman <gregkh@linuxfoundation.org>]

On Tue, Feb 07, 2023 at 11:47:16AM +0200, Ilpo Järvinen wrote:
> [ Upstream commit 31352811e13dc2313f101b890fd4b1ce760b5fe7 ]
> 
> __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: 9ee4b83e51f7 ("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>
> ---
>  drivers/tty/serial/8250/8250_dma.c | 14 +++++++++++++-
>  1 file changed, 13 insertions(+), 1 deletion(-)

Thanks, both queued up now.

greg k-h