spi: restore rx/tx_buf in case of unset CONFIG_HAS_DMA
The case where spi_master sets the flags SPI_MASTER_MUST_RX/TX while
CONFIG_HAS_DMA is unset (which is unlikley) together with a driver
that reuses spi_messages with rx/tx_buff set to NULL, can result in:
* data disclosure over the SPI (for tx_buf == NULL)
* memory corruption (for rx_buf == NULL)
This happenes when dummy_rx/dummy_tx are changing address due to krealloc
or free and an allocation of the memory by a different part of the kernel.
Signed-off-by: Martin Sperl <kernel@martin.sperl.org>
Signed-off-by: Mark Brown <broonie@kernel.org>
diff --git a/drivers/spi/spi.c b/drivers/spi/spi.c
index d35c1a1..cf8b91b 100644
--- a/drivers/spi/spi.c
+++ b/drivers/spi/spi.c
@@ -571,7 +571,7 @@
return 0;
}
-static int spi_unmap_msg(struct spi_master *master, struct spi_message *msg)
+static int __spi_unmap_msg(struct spi_master *master, struct spi_message *msg)
{
struct spi_transfer *xfer;
struct device *tx_dev, *rx_dev;
@@ -583,15 +583,6 @@
rx_dev = master->dma_rx->device->dev;
list_for_each_entry(xfer, &msg->transfers, transfer_list) {
- /*
- * Restore the original value of tx_buf or rx_buf if they are
- * NULL.
- */
- if (xfer->tx_buf == master->dummy_tx)
- xfer->tx_buf = NULL;
- if (xfer->rx_buf == master->dummy_rx)
- xfer->rx_buf = NULL;
-
if (!master->can_dma(master, msg->spi, xfer))
continue;
@@ -608,13 +599,32 @@
return 0;
}
-static inline int spi_unmap_msg(struct spi_master *master,
- struct spi_message *msg)
+static inline int __spi_unmap_msg(struct spi_master *master,
+ struct spi_message *msg)
{
return 0;
}
#endif /* !CONFIG_HAS_DMA */
+static inline int spi_unmap_msg(struct spi_master *master,
+ struct spi_message *msg)
+{
+ struct spi_transfer *xfer;
+
+ list_for_each_entry(xfer, &msg->transfers, transfer_list) {
+ /*
+ * Restore the original value of tx_buf or rx_buf if they are
+ * NULL.
+ */
+ if (xfer->tx_buf == master->dummy_tx)
+ xfer->tx_buf = NULL;
+ if (xfer->rx_buf == master->dummy_rx)
+ xfer->rx_buf = NULL;
+ }
+
+ return __spi_unmap_msg(master, msg);
+}
+
static int spi_map_msg(struct spi_master *master, struct spi_message *msg)
{
struct spi_transfer *xfer;