[PATCH 4.8 005/138] spi: fsl-espi: avoid processing uninitalized data on error

[Greg Kroah-Hartman]

4.8-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Arnd Bergmann <arnd@xxxxxxxx>

commit 5c0ba57744b1422d528f19430dd66d6803cea86f upstream.

When we get a spurious interrupt in fsl_espi_irq, we end up
processing four uninitalized bytes of data, as shown in this
warning message:

   drivers/spi/spi-fsl-espi.c: In function 'fsl_espi_irq':
   drivers/spi/spi-fsl-espi.c:462:4: warning: 'rx_data' may be used uninitialized in this function [-Wmaybe-uninitialized]

This adds another check so we skip the data in this case.

Fixes: 6319a68011b8 ("spi/fsl-espi: avoid infinite loops on fsl_espi_cpu_irq()")
Signed-off-by: Arnd Bergmann <arnd@xxxxxxxx>
Signed-off-by: Mark Brown <broonie@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 drivers/spi/spi-fsl-espi.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/drivers/spi/spi-fsl-espi.c
+++ b/drivers/spi/spi-fsl-espi.c
@@ -581,7 +581,7 @@ void fsl_espi_cpu_irq(struct mpc8xxx_spi
 
 		mspi->len -= rx_nr_bytes;
 
-		if (mspi->rx)
+		if (rx_nr_bytes && mspi->rx)
 			mspi->get_rx(rx_data, mspi);
 	}