[PATCH 6.18.y 4/4] spi: cadence-xspi: reject SDMA transfers larger than the requested length

[Sasha Levin <sashal@kernel.org>]

From: Weibin Liu <liuwb@xiaopeng.com>

[ Upstream commit ea9854a169e9c1437df8829bea21c2f2e80b137c ]

The XSPI controller reports the size of the slave-DMA transaction
through SDMA_SIZE_REG. Both SDMA handlers take this register at face
value and copy the reported number of bytes between the SDMA FIFO and
the transfer buffers, without checking it against the length of the
transfer that was actually requested.

While cdns_xspi_adjust_mem_op_size() clamps the size of the operations
issued by the SPI core, the device can still report a bigger SDMA size
than what was programmed, which makes the handlers read from or write
to memory beyond the end of the transfer buffers.

Track the number of bytes requested for the current data phase in a new
sdma_xfer_len field, set by cdns_xspi_send_stig_command() and by the
Marvell b0 transfer path, and reject any SDMA size that exceeds it.

Fixes: a16cc8077627 ("spi: cadence: add support for Cadence XSPI controller")
Cc: stable@vger.kernel.org # 5.16+
Signed-off-by: Weibin Liu <liuwb@xiaopeng.com>
Link: https://patch.msgid.link/20260929081146.41041-2-liuwb@xiaopeng.com
Signed-off-by: Mark Brown <broonie@kernel.org>
[ sashal: Adjusted context to retain ioread8_rep() and iowrite8_rep() because the wider-I/O helpers are absent. ]
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/spi/spi-cadence-xspi.c | 36 +++++++++++++++++++++++++++++-----
 1 file changed, 31 insertions(+), 5 deletions(-)

diff --git a/drivers/spi/spi-cadence-xspi.c b/drivers/spi/spi-cadence-xspi.c
index c12930ce67472..ca6af39e977a4 100644
--- a/drivers/spi/spi-cadence-xspi.c
+++ b/drivers/spi/spi-cadence-xspi.c
@@ -332,6 +332,7 @@ struct cdns_xspi_dev {
 	int irq;
 	int cur_cs;
 	unsigned int sdmasize;
+	unsigned int sdma_xfer_len;
 
 	struct completion cmd_complete;
 	struct completion auto_cmd_complete;
@@ -344,7 +345,7 @@ struct cdns_xspi_dev {
 	u8 hw_num_banks;
 
 	const struct cdns_xspi_driver_data *driver_data;
-	void (*sdma_handler)(struct cdns_xspi_dev *cdns_xspi);
+	int (*sdma_handler)(struct cdns_xspi_dev *cdns_xspi);
 	void (*set_interrupts_handler)(struct cdns_xspi_dev *cdns_xspi, bool enabled);
 
 	bool xfer_in_progress;
@@ -445,7 +446,7 @@ static int cdns_xspi_controller_init(struct cdns_xspi_dev *cdns_xspi)
 	return 0;
 }
 
-static void cdns_xspi_sdma_handle(struct cdns_xspi_dev *cdns_xspi)
+static int cdns_xspi_sdma_handle(struct cdns_xspi_dev *cdns_xspi)
 {
 	u32 sdma_size, sdma_trd_info;
 	u8 sdma_dir;
@@ -454,6 +455,13 @@ static void cdns_xspi_sdma_handle(struct cdns_xspi_dev *cdns_xspi)
 	sdma_trd_info = readl(cdns_xspi->iobase + CDNS_XSPI_SDMA_TRD_INFO_REG);
 	sdma_dir = FIELD_GET(CDNS_XSPI_SDMA_DIR, sdma_trd_info);
 
+	if (sdma_size > cdns_xspi->sdma_xfer_len) {
+		dev_err(cdns_xspi->dev,
+			"SDMA size %u exceeds the requested length %u\n",
+			sdma_size, cdns_xspi->sdma_xfer_len);
+		return -EINVAL;
+	}
+
 	switch (sdma_dir) {
 	case CDNS_XSPI_SDMA_DIR_READ:
 		ioread8_rep(cdns_xspi->sdmabase,
@@ -465,6 +473,8 @@ static void cdns_xspi_sdma_handle(struct cdns_xspi_dev *cdns_xspi)
 			     cdns_xspi->out_buffer, sdma_size);
 		break;
 	}
+
+	return 0;
 }
 
 static int cdns_xspi_send_stig_command(struct cdns_xspi_dev *cdns_xspi,
@@ -510,6 +520,7 @@ static int cdns_xspi_send_stig_command(struct cdns_xspi_dev *cdns_xspi,
 
 		cdns_xspi->in_buffer = op->data.buf.in;
 		cdns_xspi->out_buffer = op->data.buf.out;
+		cdns_xspi->sdma_xfer_len = op->data.nbytes;
 
 		cdns_xspi_trigger_command(cdns_xspi, cmd_regs);
 
@@ -518,7 +529,11 @@ static int cdns_xspi_send_stig_command(struct cdns_xspi_dev *cdns_xspi,
 			cdns_xspi->set_interrupts_handler(cdns_xspi, false);
 			return -EIO;
 		}
-		cdns_xspi->sdma_handler(cdns_xspi);
+		ret = cdns_xspi->sdma_handler(cdns_xspi);
+		if (ret) {
+			cdns_xspi->set_interrupts_handler(cdns_xspi, false);
+			return ret;
+		}
 	}
 
 	wait_for_completion(&cdns_xspi->cmd_complete);
@@ -900,7 +915,7 @@ static void m_iowriteq(void __iomem *addr, const void *buf, int len)
 	}
 }
 
-static void marvell_xspi_sdma_handle(struct cdns_xspi_dev *cdns_xspi)
+static int marvell_xspi_sdma_handle(struct cdns_xspi_dev *cdns_xspi)
 {
 	u32 sdma_size, sdma_trd_info;
 	u8 sdma_dir;
@@ -909,6 +924,13 @@ static void marvell_xspi_sdma_handle(struct cdns_xspi_dev *cdns_xspi)
 	sdma_trd_info = readl(cdns_xspi->iobase + CDNS_XSPI_SDMA_TRD_INFO_REG);
 	sdma_dir = FIELD_GET(CDNS_XSPI_SDMA_DIR, sdma_trd_info);
 
+	if (sdma_size > cdns_xspi->sdma_xfer_len) {
+		dev_err(cdns_xspi->dev,
+			"SDMA size %u exceeds the requested length %u\n",
+			sdma_size, cdns_xspi->sdma_xfer_len);
+		return -EINVAL;
+	}
+
 	switch (sdma_dir) {
 	case CDNS_XSPI_SDMA_DIR_READ:
 		m_ioreadq(cdns_xspi->sdmabase,
@@ -920,6 +942,8 @@ static void marvell_xspi_sdma_handle(struct cdns_xspi_dev *cdns_xspi)
 			     cdns_xspi->out_buffer, sdma_size);
 		break;
 	}
+
+	return 0;
 }
 
 static const struct spi_controller_mem_ops marvell_xspi_mem_ops = {
@@ -1084,9 +1108,11 @@ static int cdns_xspi_transfer_one_message_b0(struct spi_controller *controller,
 				cdns_xspi_prepare_transfer(cs, 1, current_transfer_len - 1,
 							   cmd_regs);
 				cdns_xspi_trigger_command(cdns_xspi, cmd_regs);
+				cdns_xspi->sdma_xfer_len = current_transfer_len - 1;
 				if (!cdns_xspi_is_sdma_ready(cdns_xspi, true))
 					return -EIO;
-				cdns_xspi->sdma_handler(cdns_xspi);
+				if (cdns_xspi->sdma_handler(cdns_xspi))
+					return -EIO;
 				if (!cdns_xspi_is_stig_ready(cdns_xspi, true))
 					return -EIO;
 
-- 
2.53.0