From 380583227c0c7f52383b0cd5c0e2de93ed31d553 Mon Sep 17 00:00:00 2001
From: Boris Brezillon <boris.brezillon@bootlin.com>
Date: Thu, 20 Sep 2018 09:31:12 +0200
Subject: [PATCH] spi: spi-mem: Add extra sanity checks on the op param

Some combinations are simply not valid and should be rejected before
the op is passed to the SPI controller driver.

Add an spi_mem_check_op() helper and use it in spi_mem_exec_op() and
spi_mem_supports_op() to make sure the spi-mem operation is valid.

Signed-off-by: Boris Brezillon <boris.brezillon@bootlin.com>
Signed-off-by: Mark Brown <broonie@kernel.org>
---
 drivers/spi/spi-mem.c | 54 ++++++++++++++++++++++++++++++++++++++-----
 1 file changed, 48 insertions(+), 6 deletions(-)

diff --git a/drivers/spi/spi-mem.c b/drivers/spi/spi-mem.c
index eb72dba71d83..cc3d425aae56 100644
--- a/drivers/spi/spi-mem.c
+++ b/drivers/spi/spi-mem.c
@@ -12,6 +12,8 @@
 
 #include "internals.h"
 
+#define SPI_MEM_MAX_BUSWIDTH		4
+
 /**
  * spi_controller_dma_map_mem_op_data() - DMA-map the buffer attached to a
  *					  memory operation
@@ -149,6 +151,44 @@ static bool spi_mem_default_supports_op(struct spi_mem *mem,
 }
 EXPORT_SYMBOL_GPL(spi_mem_default_supports_op);
 
+static bool spi_mem_buswidth_is_valid(u8 buswidth)
+{
+	if (hweight8(buswidth) > 1 || buswidth > SPI_MEM_MAX_BUSWIDTH)
+		return false;
+
+	return true;
+}
+
+static int spi_mem_check_op(const struct spi_mem_op *op)
+{
+	if (!op->cmd.buswidth)
+		return -EINVAL;
+
+	if ((op->addr.nbytes && !op->addr.buswidth) ||
+	    (op->dummy.nbytes && !op->dummy.buswidth) ||
+	    (op->data.nbytes && !op->data.buswidth))
+		return -EINVAL;
+
+	if (spi_mem_buswidth_is_valid(op->cmd.buswidth) ||
+	    spi_mem_buswidth_is_valid(op->addr.buswidth) ||
+	    spi_mem_buswidth_is_valid(op->dummy.buswidth) ||
+	    spi_mem_buswidth_is_valid(op->data.buswidth))
+		return -EINVAL;
+
+	return 0;
+}
+
+static bool spi_mem_internal_supports_op(struct spi_mem *mem,
+					 const struct spi_mem_op *op)
+{
+	struct spi_controller *ctlr = mem->spi->controller;
+
+	if (ctlr->mem_ops && ctlr->mem_ops->supports_op)
+		return ctlr->mem_ops->supports_op(mem, op);
+
+	return spi_mem_default_supports_op(mem, op);
+}
+
 /**
  * spi_mem_supports_op() - Check if a memory device and the controller it is
  *			   connected to support a specific memory operation
@@ -166,12 +206,10 @@ EXPORT_SYMBOL_GPL(spi_mem_default_supports_op);
  */
 bool spi_mem_supports_op(struct spi_mem *mem, const struct spi_mem_op *op)
 {
-	struct spi_controller *ctlr = mem->spi->controller;
+	if (spi_mem_check_op(op))
+		return false;
 
-	if (ctlr->mem_ops && ctlr->mem_ops->supports_op)
-		return ctlr->mem_ops->supports_op(mem, op);
-
-	return spi_mem_default_supports_op(mem, op);
+	return spi_mem_internal_supports_op(mem, op);
 }
 EXPORT_SYMBOL_GPL(spi_mem_supports_op);
 
@@ -196,7 +234,11 @@ int spi_mem_exec_op(struct spi_mem *mem, const struct spi_mem_op *op)
 	u8 *tmpbuf;
 	int ret;
 
-	if (!spi_mem_supports_op(mem, op))
+	ret = spi_mem_check_op(op);
+	if (ret)
+		return ret;
+
+	if (!spi_mem_internal_supports_op(mem, op))
 		return -ENOTSUPP;
 
 	if (ctlr->mem_ops) {