Commit de327e49 authored by Nicolas Boichat's avatar Nicolas Boichat Committed by Mark Brown
Browse files

spi: mediatek: Prevent overflows in FIFO transfers 



In the case where transfer length is not a multiple of 4, KASAN
reports 2 out-of-bounds memory accesses:
 - mtk_spi_interrupt: ioread32_rep writes past the end of
   trans->rx_buf.
 - mtk_spi_fifo_transfer: iowrite32_rep reads past the end of
   xfer->tx_buf.

Fix this by using memcpy on the remainder of the bytes.

Signed-off-by: default avatarNicolas Boichat <drinkcat@chromium.org>
Signed-off-by: default avatarMark Brown <broonie@kernel.org>
parent 8005c49d

drivers/spi/spi-mt65xx.c

+18 −10
Original line number Diff line number Diff line
@@ -323,7 +323,8 @@ static int mtk_spi_fifo_transfer(struct spi_master *master, 
				 struct spi_device *spi,

				 struct spi_transfer *xfer)

{

	int cnt;

	int cnt, remainder;

	u32 reg_val;

	struct mtk_spi *mdata = spi_master_get_devdata(master);



	mdata->cur_transfer = xfer;
@@ -331,12 +332,16 @@ static int mtk_spi_fifo_transfer(struct spi_master *master, 
	mtk_spi_prepare_transfer(master, xfer);

	mtk_spi_setup_packet(master);



	if (xfer->len % 4)

		cnt = xfer->len / 4 + 1;

	else

	cnt = xfer->len / 4;

	iowrite32_rep(mdata->base + SPI_TX_DATA_REG, xfer->tx_buf, cnt);



	remainder = xfer->len % 4;

	if (remainder > 0) {

		reg_val = 0;

		memcpy(&reg_val, xfer->tx_buf + (cnt * 4), remainder);

		writel(reg_val, mdata->base + SPI_TX_DATA_REG);

	}



	mtk_spi_enable_transfer(master);



	return 1;
@@ -418,7 +423,7 @@ static int mtk_spi_setup(struct spi_device *spi) 


static irqreturn_t mtk_spi_interrupt(int irq, void *dev_id)

{

	u32 cmd, reg_val, cnt;

	u32 cmd, reg_val, cnt, remainder;

	struct spi_master *master = dev_id;

	struct mtk_spi *mdata = spi_master_get_devdata(master);

	struct spi_transfer *trans = mdata->cur_transfer;
@@ -431,12 +436,15 @@ static irqreturn_t mtk_spi_interrupt(int irq, void *dev_id) 


	if (!master->can_dma(master, master->cur_msg->spi, trans)) {

		if (trans->rx_buf) {

			if (mdata->xfer_len % 4)

				cnt = mdata->xfer_len / 4 + 1;

			else

			cnt = mdata->xfer_len / 4;

			ioread32_rep(mdata->base + SPI_RX_DATA_REG,

				     trans->rx_buf, cnt);

			remainder = mdata->xfer_len % 4;

			if (remainder > 0) {

				reg_val = readl(mdata->base + SPI_RX_DATA_REG);

				memcpy(trans->rx_buf + (cnt * 4),

					&reg_val, remainder);

			}

		}

		spi_finalize_current_transfer(master);

		return IRQ_HANDLED;

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