[PATCH] bus: imx-weim: Remove VLA usage

* [PATCH] bus: imx-weim: Remove VLA usage
@ 2018-06-29 18:52 Kees Cook
  2018-06-29 19:45 ` Rob Herring
  2018-06-29 21:28 ` Arnd Bergmann
  0 siblings, 2 replies; 5+ messages in thread
From: Kees Cook @ 2018-06-29 18:52 UTC (permalink / raw)
  To: Maxime Ripard; +Cc: Arnd Bergmann, Rob Herring, linux-kernel

In the quest to remove all stack VLA usage from the kernel[1], this
switches to using a maximum size and adds a sanity check.

[1] https://lkml.kernel.org/r/CA+55aFzCG-zNmZwX4A2FQpadafLfEzK6CC=qPXydAacU1RqZWA@mail.gmail.com

Cc: Maxime Ripard <maxime.ripard@free-electrons.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Rob Herring <robh@kernel.org>
Signed-off-by: Kees Cook <keescook@chromium.org>
---
 drivers/bus/imx-weim.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/drivers/bus/imx-weim.c b/drivers/bus/imx-weim.c
index 3d56ebcda720..6a94aa6a22c2 100644
--- a/drivers/bus/imx-weim.c
+++ b/drivers/bus/imx-weim.c
@@ -45,6 +45,8 @@ static const struct imx_weim_devtype imx51_weim_devtype = {
 	.cs_stride	= 0x18,
 };
 
+#define MAX_CS_REGS_COUNT	6
+
 static const struct of_device_id weim_id_table[] = {
 	/* i.MX1/21 */
 	{ .compatible = "fsl,imx1-weim", .data = &imx1_weim_devtype, },
@@ -112,9 +114,12 @@ static int __init imx_weim_gpr_setup(struct platform_device *pdev)
 static int __init weim_timing_setup(struct device_node *np, void __iomem *base,
 				    const struct imx_weim_devtype *devtype)
 {
-	u32 cs_idx, value[devtype->cs_regs_count];
+	u32 cs_idx, value[MAX_CS_REGS_COUNT];
 	int i, ret;
 
+	if (WARN_ON(devtype->cs_regs_count > MAX_CS_REGS_COUNT))
+		return -EINVAL;
+
 	/* get the CS index from this child node's "reg" property. */
 	ret = of_property_read_u32(np, "reg", &cs_idx);
 	if (ret)
-- 
2.17.1


-- 
Kees Cook
Pixel Security

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