serial: 8250_dma: Fix DMA Rx completion race
authorIlpo Järvinen <ilpo.jarvinen@linux.intel.com>
Mon, 30 Jan 2023 11:48:40 +0000 (13:48 +0200)
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Tue, 31 Jan 2023 10:15:16 +0000 (11:15 +0100)
commit31352811e13dc2313f101b890fd4b1ce760b5fe7
treec1ce607a9228b0e54e1c9b7c64e648b0a4ee90f6
parent3f6c02fa712bd453871877fe1d1969625617471e
serial: 8250_dma: Fix DMA Rx completion race

__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