Patch "spi: spi-mt65xx: Fix NULL pointer access in interrupt handler" has been added to the 6.8-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

This is a note to let you know that I've just added the patch titled

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

to the 6.8-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     spi-spi-mt65xx-fix-null-pointer-access-in-interrupt-.patch
and it can be found in the queue-6.8 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit eaaf406e0612d5f4238797a18b7ea2be1a93a754
Author: Fei Shao <fshao@xxxxxxxxxxxx>
Date:   Thu Mar 21 15:08:57 2024 +0800

    spi: spi-mt65xx: Fix NULL pointer access in interrupt handler
    
    [ 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@xxxxxxxxxxxx>
    Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@xxxxxxxxxxxxx>
    Link: https://msgid.link/r/20240321070942.1587146-2-fshao@xxxxxxxxxxxx
    Signed-off-by: Mark Brown <broonie@xxxxxxxxxx>
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/drivers/spi/spi-mt65xx.c b/drivers/spi/spi-mt65xx.c
index 8d5d170d49cc4..109dac2e69df2 100644
--- a/drivers/spi/spi-mt65xx.c
+++ b/drivers/spi/spi-mt65xx.c
@@ -787,17 +787,19 @@ 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(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);