[PATCH 5.10 005/131] spi: spi-zynq-qspi: Fix stack violation bug

From: Greg Kroah-Hartman
Date: Mon Jun 14 2021 - 07:05:27 EST


From: Karen Dombroski <karen.dombroski@xxxxxxxxxxxxxxxxxx>

[ Upstream commit 6d5ff8e632a4f2389c331e5554cd1c2a9a28c7aa ]

When the number of bytes for the op is greater than one, the read could
run off the end of the function stack and cause a crash.

This patch restores the behaviour of safely reading out of the original
opcode location.

Signed-off-by: Karen Dombroski <karen.dombroski@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Amit Kumar Mahapatra <amit.kumar-mahapatra@xxxxxxxxxx>
Link: https://lore.kernel.org/r/20210429053802.17650-3-amit.kumar-mahapatra@xxxxxxxxxx
Signed-off-by: Mark Brown <broonie@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
drivers/spi/spi-zynq-qspi.c | 7 +++----
1 file changed, 3 insertions(+), 4 deletions(-)

diff --git a/drivers/spi/spi-zynq-qspi.c b/drivers/spi/spi-zynq-qspi.c
index 5d8a5ee62fa2..2765289028fa 100644
--- a/drivers/spi/spi-zynq-qspi.c
+++ b/drivers/spi/spi-zynq-qspi.c
@@ -528,18 +528,17 @@ static int zynq_qspi_exec_mem_op(struct spi_mem *mem,
struct zynq_qspi *xqspi = spi_controller_get_devdata(mem->spi->master);
int err = 0, i;
u8 *tmpbuf;
- u8 opcode = op->cmd.opcode;

dev_dbg(xqspi->dev, "cmd:%#x mode:%d.%d.%d.%d\n",
- opcode, op->cmd.buswidth, op->addr.buswidth,
+ op->cmd.opcode, op->cmd.buswidth, op->addr.buswidth,
op->dummy.buswidth, op->data.buswidth);

zynq_qspi_chipselect(mem->spi, true);
zynq_qspi_config_op(xqspi, mem->spi);

- if (op->cmd.nbytes) {
+ if (op->cmd.opcode) {
reinit_completion(&xqspi->data_completion);
- xqspi->txbuf = &opcode;
+ xqspi->txbuf = (u8 *)&op->cmd.opcode;
xqspi->rxbuf = NULL;
xqspi->tx_bytes = op->cmd.nbytes;
xqspi->rx_bytes = op->cmd.nbytes;
--
2.30.2