linux-kernel - [PATCH] i2c: mlxbf: Fix out-of-bounds bug in mlxbf_i2c_smbus

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Message-Id: <20250607214255.2579865-1-alexguo1023@gmail.com>
Date: Sat,  7 Jun 2025 17:42:55 -0400
From: Alex Guo <alexguo1023@...il.com>
To: kblaiech@...dia.com,
	asmaa@...dia.com
Cc: andi.shyti@...nel.org,
	linux-i2c@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	Alex Guo <alexguo1023@...il.com>
Subject: [PATCH] i2c: mlxbf: Fix out-of-bounds bug in mlxbf_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.

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-mlxbf.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/drivers/i2c/busses/i2c-mlxbf.c b/drivers/i2c/busses/i2c-mlxbf.c
index 8345f7e6385d..73fe8914f3f1 100644
--- a/drivers/i2c/busses/i2c-mlxbf.c
+++ b/drivers/i2c/busses/i2c-mlxbf.c
@@ -2071,6 +2071,8 @@ static s32 mlxbf_i2c_smbus_xfer(struct i2c_adapter *adap, u16 addr,
 		break;
 
 	case I2C_SMBUS_I2C_BLOCK_DATA:
+		if (data->block[0] < 1 || data->block[0] > I2C_SMBUS_BLOCK_MAX)
+			return -EINVAL;
 		byte_cnt = data->block[0];
 		mlxbf_i2c_smbus_i2c_block_func(&request, &command, data->block,
 					       &byte_cnt, read, pec);
@@ -2079,6 +2081,8 @@ static s32 mlxbf_i2c_smbus_xfer(struct i2c_adapter *adap, u16 addr,
 		break;
 
 	case I2C_SMBUS_BLOCK_DATA:
+		if (data->block[0] < 1 || data->block[0] > I2C_SMBUS_BLOCK_MAX)
+			return -EINVAL;
 		byte_cnt = read ? I2C_SMBUS_BLOCK_MAX : data->block[0];
 		mlxbf_i2c_smbus_block_func(&request, &command, data->block,
 					   &byte_cnt, read, pec);
@@ -2094,6 +2098,8 @@ static s32 mlxbf_i2c_smbus_xfer(struct i2c_adapter *adap, u16 addr,
 		break;
 
 	case I2C_FUNC_SMBUS_BLOCK_PROC_CALL:
+		if (data->block[0] < 1 || data->block[0] > I2C_SMBUS_BLOCK_MAX)
+			return -EINVAL;
 		byte_cnt = data->block[0];
 		mlxbf_i2c_smbus_blk_process_call_func(&request, &command,
 						      data->block, &byte_cnt,
-- 
2.34.1