[PATCH] mtd: spi-nor: Fix integer overflow in stacked memories support

[Marek Vasut]

The 5d40b3d384dc ("mtd: spi-nor: Add parallel and stacked memories support")
adds new SPI bus flags, but also introduces a completely new set of
SPI bus flags in another location. The existing flags field is type
u8, while the new separate flags are BIT(8) and higher. Use of those
new flags triggers integer overflow.

Drop the newly introduced flags which were never used anywhere in the
code. Move the one remaining flag which was used in the correct place
and change it from BIT(8) to BIT(6) so it fits the u8 flags.

Fixes: 5d40b3d384dc ("mtd: spi-nor: Add parallel and stacked memories support")
Addresses-Coverity-ID: 510804 Extra high-order bits
Reported-by: Heinrich Schuchardt <xypron.glpk at gmx.de>
Signed-off-by: Marek Vasut <marek.vasut+renesas at mailbox.org>
---
Cc: "Cédric Le Goater" <clg at kaod.org>
Cc: Ashok Reddy Soma <ashok.reddy.soma at amd.com>
Cc: Heinrich Schuchardt <xypron.glpk at gmx.de>
Cc: Ibai Erkiaga <ibai.erkiaga-elorza at amd.com>
Cc: Jagan Teki <jagan at amarulasolutions.com>
Cc: Michal Simek <michal.simek at amd.com>
Cc: Tom Rini <trini at konsulko.com>
Cc: Venkatesh Yadav Abbarapu <venkatesh.abbarapu at amd.com>
Cc: William Zhang <william.zhang at broadcom.com>
---
Maybe we should revert the whole stacked patchset until it is fixed properly ?
---
 drivers/spi/zynq_qspi.c    | 2 +-
 drivers/spi/zynqmp_gqspi.c | 6 +++---
 include/spi.h              | 8 ++------
 3 files changed, 6 insertions(+), 10 deletions(-)

diff --git a/drivers/spi/zynq_qspi.c b/drivers/spi/zynq_qspi.c
index 4aad3248d9e..e43dbb40c4a 100644
--- a/drivers/spi/zynq_qspi.c
+++ b/drivers/spi/zynq_qspi.c
@@ -813,7 +813,7 @@ static int zynq_qspi_exec_op(struct spi_slave *slave,
 
 	priv->is_parallel = false;
 	priv->is_stacked = false;
-	slave->flags &= ~SPI_XFER_MASK;
+	slave->flags &= ~SPI_XFER_LOWER;
 	spi_release_bus(slave);
 
 	return 0;
diff --git a/drivers/spi/zynqmp_gqspi.c b/drivers/spi/zynqmp_gqspi.c
index 1d19b2606c5..4251bf28cd3 100644
--- a/drivers/spi/zynqmp_gqspi.c
+++ b/drivers/spi/zynqmp_gqspi.c
@@ -870,8 +870,8 @@ static int zynqmp_qspi_exec_op(struct spi_slave *slave,
 	priv->bus = 0;
 
 	if (priv->is_parallel) {
-		if (slave->flags & SPI_XFER_MASK)
-			priv->bus = (slave->flags & SPI_XFER_MASK) >> 8;
+		if (slave->flags & SPI_XFER_LOWER)
+			priv->bus = 1;
 		if (zynqmp_qspi_update_stripe(op))
 			priv->stripe = 1;
 	}
@@ -890,7 +890,7 @@ static int zynqmp_qspi_exec_op(struct spi_slave *slave,
 	zynqmp_qspi_chipselect(priv, 0);
 
 	priv->is_parallel = false;
-	slave->flags &= ~SPI_XFER_MASK;
+	slave->flags &= ~SPI_XFER_LOWER;
 
 	return ret;
 }
diff --git a/include/spi.h b/include/spi.h
index 3a92d02f215..6944773b596 100644
--- a/include/spi.h
+++ b/include/spi.h
@@ -41,12 +41,6 @@
 #define SPI_3BYTE_MODE 0x0
 #define SPI_4BYTE_MODE 0x1
 
-/* SPI transfer flags */
-#define SPI_XFER_STRIPE	(1 << 6)
-#define SPI_XFER_MASK	(3 << 8)
-#define SPI_XFER_LOWER	(1 << 8)
-#define SPI_XFER_UPPER	(2 << 8)
-
 /* Max no. of CS supported per spi device */
 #define SPI_CS_CNT_MAX	2
 
@@ -169,6 +163,8 @@ struct spi_slave {
 #define SPI_XFER_ONCE		(SPI_XFER_BEGIN | SPI_XFER_END)
 #define SPI_XFER_U_PAGE		BIT(4)
 #define SPI_XFER_STACKED	BIT(5)
+#define SPI_XFER_LOWER		BIT(6)
+
 	/*
 	 * Flag indicating that the spi-controller has multi chip select
 	 * capability and can assert/de-assert more than one chip select
-- 
2.45.2