linux-kernel - [PATCH] i2c: busses: Fix out-of-bounds bug in mchp_corei2c_smbus

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Message-Id: <20250615234919.525431-1-alexguo1023@gmail.com>
Date: Sun, 15 Jun 2025 19:49:19 -0400
From: Alex Guo <alexguo1023@...il.com>
To: conor.dooley@...rochip.com
Cc: alexguo1023@...il.com,
	daire.mcnamara@...rochip.com,
	andi.shyti@...nel.org,
	linux-riscv@...ts.infradead.org,
	linux-i2c@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: [PATCH] i2c: busses: Fix out-of-bounds bug in mchp_corei2c_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.

Similar commit:
1. commit 39244cc7548 ("i2c: ismt: Fix an out-of-bounds bug in
ismt_access()")
2. commit 92fbb6d1296 ("i2c: xgene-slimpro: Fix out-of-bounds
bug in xgene_slimpro_i2c_xfer()")

Signed-off-by: Alex Guo <alexguo1023@...il.com>
---
 drivers/i2c/busses/i2c-microchip-corei2c.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/i2c/busses/i2c-microchip-corei2c.c b/drivers/i2c/busses/i2c-microchip-corei2c.c
index 492bf4c34722..a79d4d327f20 100644
--- a/drivers/i2c/busses/i2c-microchip-corei2c.c
+++ b/drivers/i2c/busses/i2c-microchip-corei2c.c
@@ -492,6 +492,8 @@ static int mchp_corei2c_smbus_xfer(struct i2c_adapter *adap, u16 addr, unsigned
 		if (read_write == I2C_SMBUS_WRITE) {
 			int data_len;
 
+			if (data->block[0] < 1 || data->block[0] > I2C_SMBUS_BLOCK_MAX)
+				return -EINVAL;
 			data_len = data->block[0];
 			msgs[CORE_I2C_SMBUS_MSG_WR].len = data_len + 2;
 			for (int i = 0; i <= data_len; i++)
-- 
2.34.1