From 57f312b955938fc4663f430cb57a71f2414f601b Mon Sep 17 00:00:00 2001
From: Alex Guo <alexguo1023@gmail.com>
Date: Sun, 10 Aug 2025 20:05:13 +0200
Subject: [PATCH] i2c: rtl9300: Fix out-of-bounds bug in rtl9300_i2c_smbus_xfer

The data->block[0] variable comes from user. Without proper check,
the variable may be very large to cause an out-of-bounds bug.

Fix this bug by checking the value of data->block[0] first.

1. commit 39244cc75482 ("i2c: ismt: Fix an out-of-bounds bug in
   ismt_access()")
2. commit 92fbb6d1296f ("i2c: xgene-slimpro: Fix out-of-bounds bug in
   xgene_slimpro_i2c_xfer()")

Fixes: c366be720235 ("i2c: Add driver for the RTL9300 I2C controller")
Signed-off-by: Alex Guo <alexguo1023@gmail.com>
Cc: <stable@vger.kernel.org> # v6.13+
Reviewed-by: Chris Packham <chris.packham@alliedtelesis.co.nz>
Tested-by: Chris Packham <chris.packham@alliedtelesis.co.nz>
Reviewed-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Signed-off-by: Sven Eckelmann <sven@narfation.org>
Signed-off-by: Andi Shyti <andi.shyti@kernel.org>
Link: https://lore.kernel.org/r/20250810-i2c-rtl9300-multi-byte-v5-1-cd9dca0db722@narfation.org

--- a/drivers/i2c/busses/i2c-rtl9300.c
+++ b/drivers/i2c/busses/i2c-rtl9300.c
@@ -281,6 +281,10 @@ static int rtl9300_i2c_smbus_xfer(struct
 		ret = rtl9300_i2c_reg_addr_set(i2c, command, 1);
 		if (ret)
 			goto out_unlock;
+		if (data->block[0] < 1 || data->block[0] > I2C_SMBUS_BLOCK_MAX) {
+			ret = -EINVAL;
+			goto out_unlock;
+		}
 		ret = rtl9300_i2c_config_xfer(i2c, chan, addr, data->block[0]);
 		if (ret)
 			goto out_unlock;
