[PATCH] bus: sunxi-rsb: Always check register address validity

[Andrey Skvortsov <andrej.skvortzov@gmail.com>]

From: Samuel Holland <samuel@sholland.org>

The register address was already validated for read operations in
regmap_sunxi_rsb_reg_read before being truncated to a u8. Write operations
have the same set of possible addresses, and the address is being truncated
from u32 to u8 here as well, so the same check is needed.

Signed-off-by: Samuel Holland <samuel@sholland.org>
Signed-off-by: Andrey Skvortsov <andrej.skvortzov@gmail.com>
---
 drivers/bus/sunxi-rsb.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/bus/sunxi-rsb.c b/drivers/bus/sunxi-rsb.c
index b4f2c64ac1810..daf0ea563e477 100644
--- a/drivers/bus/sunxi-rsb.c
+++ b/drivers/bus/sunxi-rsb.c
@@ -445,6 +445,9 @@ static int regmap_sunxi_rsb_reg_write(void *context, unsigned int reg,
 	struct sunxi_rsb_ctx *ctx = context;
 	struct sunxi_rsb_device *rdev = ctx->rdev;
 
+	if (reg > 0xff)
+		return -EINVAL;
+
 	return sunxi_rsb_write(rdev->rsb, rdev->rtaddr, reg, &val, ctx->size);
 }
 
-- 
2.51.0