From: Martin Sperl <[email protected]> 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 <[email protected]> --- drivers/spi/spi.c | 34 ++++++++++++++++++++++------------ 1 file changed, 22 insertions(+), 12 deletions(-) diff --git a/drivers/spi/spi.c b/drivers/spi/spi.c index 647a8bb..01e92f9 100644 --- a/drivers/spi/spi.c +++ b/drivers/spi/spi.c @@ -571,7 +571,7 @@ static int __spi_map_msg(struct spi_master *master, struct spi_message *msg) 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 @@ static int spi_unmap_msg(struct spi_master *master, struct spi_message *msg) 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 @@ static inline int __spi_map_msg(struct spi_master *master, 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; -- 1.7.10.4 -- To unsubscribe from this list: send the line "unsubscribe linux-spi" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
