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spi: mediatek: Prevent overflows in FIFO transfers

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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: Nicolas Boichat <drinkcat@chromium.org>
Signed-off-by: Mark Brown <broonie@kernel.org>
This commit is contained in:
Nicolas Boichat 2015-12-27 18:17:06 +08:00 committed by Mark Brown
parent 8005c49d9a
commit de327e4966
1 changed files with 18 additions and 10 deletions
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28
drivers/spi/spi-mt65xx.c
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@ -323,7 +323,8 @@ static int mtk_spi_fifo_transfer(struct spi_master *master,
struct spi_device *spi, struct spi_device *spi,
struct spi_transfer *xfer) struct spi_transfer *xfer)
{ {
int cnt; int cnt, remainder;
u32 reg_val;
struct mtk_spi *mdata = spi_master_get_devdata(master); struct mtk_spi *mdata = spi_master_get_devdata(master);
mdata->cur_transfer = xfer; 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_prepare_transfer(master, xfer);
mtk_spi_setup_packet(master); mtk_spi_setup_packet(master);
if (xfer->len % 4) cnt = 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); 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); mtk_spi_enable_transfer(master);
return 1; 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) 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 spi_master *master = dev_id;
struct mtk_spi *mdata = spi_master_get_devdata(master); struct mtk_spi *mdata = spi_master_get_devdata(master);
struct spi_transfer *trans = mdata->cur_transfer; 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 (!master->can_dma(master, master->cur_msg->spi, trans)) {
if (trans->rx_buf) { if (trans->rx_buf) {
if (mdata->xfer_len % 4) cnt = mdata->xfer_len / 4;
cnt = mdata->xfer_len / 4 + 1;
else
cnt = mdata->xfer_len / 4;
ioread32_rep(mdata->base + SPI_RX_DATA_REG, ioread32_rep(mdata->base + SPI_RX_DATA_REG,
trans->rx_buf, cnt); 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); spi_finalize_current_transfer(master);
return IRQ_HANDLED; return IRQ_HANDLED;