spi/xilinx: Fix access invalid memory on xilinx_spi_tx

On 1 and 2 bytes per word, the transfer of the 3 last bytes will access
memory outside tx_ptr.

Although this has not trigger any error on real hardware, we should
better fix this.

Fixes: 24ba5e593f391507 (Remove rx_fn and tx_fn pointer)
Signed-off-by: Ricardo Ribalda Delgado <ricardo.ribalda@gmail.com>
Signed-off-by: Mark Brown <broonie@kernel.org>

1 files changed, 16 insertions, 1 deletions

diff --git a/drivers/spi/spi-xilinx.c b/drivers/spi/spi-xilinx.c
index d1901d578823..133f53a9c1d4 100644
--- a/drivers/spi/spi-xilinx.c
+++ b/drivers/spi/spi-xilinx.c
@@ -117,11 +117,26 @@ static unsigned int xspi_read32_be(void __iomem *addr)
 
 static void xilinx_spi_tx(struct xilinx_spi *xspi)
 {
+        u32 data = 0;
+
         if (!xspi->tx_ptr) {
                 xspi->write_fn(0, xspi->regs + XSPI_TXD_OFFSET);
                 return;
         }
-        xspi->write_fn(*(u32 *)(xspi->tx_ptr), xspi->regs + XSPI_TXD_OFFSET);
+
+        switch (xspi->bytes_per_word) {
+        case 1:
+                data = *(u8 *)(xspi->tx_ptr);
+                break;
+        case 2:
+                data = *(u16 *)(xspi->tx_ptr);
+                break;
+        case 4:
+                data = *(u32 *)(xspi->tx_ptr);
+                break;
+        }
+
+        xspi->write_fn(data, xspi->regs + XSPI_TXD_OFFSET);
         xspi->tx_ptr += xspi->bytes_per_word;
 }