[PATCH 5.15 315/317] spi: spi-mt65xx: Fix NULL pointer access in interrupt handler

Sasha Levin
2024-03-24T23:40:08Z

From: Fei Shao <fshao@chromium.org>

[ Upstream commit a20ad45008a7c82f1184dc6dee280096009ece55 ]

The TX buffer in spi_transfer can be a NULL pointer, so the interrupt
handler may end up writing to the invalid memory and cause crashes.

Add a check to trans->tx_buf before using it.

Fixes: 1ce24864bff4 ("spi: mediatek: Only do dma for 4-byte aligned buffers")
Signed-off-by: Fei Shao <fshao@chromium.org>
Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Link: https://msgid.link/r/20240321070942.1587146-2-fshao@chromium.org
Signed-off-by: Mark Brown <broonie@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/spi/spi-mt65xx.c | 22 ++++++++++++----------
1 file changed, 12 insertions(+), 10 deletions(-)

diff --git a/drivers/spi/spi-mt65xx.c b/drivers/spi/spi-mt65xx.c
index 49acba1dea1e7..30aac6f093b21 100644
--- a/drivers/spi/spi-mt65xx.c
+++ b/drivers/spi/spi-mt65xx.c
@@ -659,17 +659,19 @@ static irqreturn_t mtk_spi_interrupt(int irq, void *dev_id)
mdata->xfer_len = min(MTK_SPI_MAX_FIFO_SIZE, len);
mtk_spi_setup_packet(master);

- cnt = mdata->xfer_len / 4;
- iowrite32_rep(mdata->base + SPI_TX_DATA_REG,
- trans->tx_buf + mdata->num_xfered, cnt);
+ if (trans->tx_buf) {
+ cnt = mdata->xfer_len / 4;
+ iowrite32_rep(mdata->base + SPI_TX_DATA_REG,
+ trans->tx_buf + mdata->num_xfered, cnt);

- remainder = mdata->xfer_len % 4;
- if (remainder > 0) {
- reg_val = 0;
- memcpy(&reg_val,
- trans->tx_buf + (cnt * 4) + mdata->num_xfered,
- remainder);
- writel(reg_val, mdata->base + SPI_TX_DATA_REG);
+ remainder = mdata->xfer_len % 4;
+ if (remainder > 0) {
+ reg_val = 0;
+ memcpy(&reg_val,
+ trans->tx_buf + (cnt * 4) + mdata->num_xfered,
+ remainder);
+ writel(reg_val, mdata->base + SPI_TX_DATA_REG);
+ }
}

mtk_spi_enable_transfer(master);
--
2.43.0