commit a20ad45008a7c82f1184dc6dee280096009ece55
author Fei Shao <fshao@chromium.org> Thu Mar 21 15:08:57 2024 +0800
committer Mark Brown <broonie@kernel.org> Thu Mar 21 11:28:21 2024 +0000
tree b8c512981fb37efb39ca9643c8d9c16b4984cbeb
parent 2ff0573e7aff5129d73ec5c3159cd84d862cb1cc

spi: spi-mt65xx: Fix NULL pointer access in interrupt handler

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>

drivers/spi/spi-mt65xx.c

diff --git a/drivers/spi/spi-mt65xx.c b/drivers/spi/spi-mt65xx.c
index 8d4633b..e4cb22f 100644
--- a/drivers/spi/spi-mt65xx.c
+++ b/drivers/spi/spi-mt65xx.c
@@ -788,17 +788,19 @@
 		mdata->xfer_len = min(MTK_SPI_MAX_FIFO_SIZE, len);
 		mtk_spi_setup_packet(host);
 
-		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(host);