[PATCH] i2c: xgene-slimpro: Fix out-of-bounds bug in xgene_slimpro_i2c_xfer()

[Wei Chen <harperchen1110@gmail.com>]

The data->block[0] variable comes from user and is a number between
0-255. Without proper check, the variable may be very large to cause
an out-of-bounds when performing memcpy in slimpro_i2c_blkwr.

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

Signed-off-by: Wei Chen <harperchen1110@gmail.com>
---
 drivers/i2c/busses/i2c-xgene-slimpro.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/drivers/i2c/busses/i2c-xgene-slimpro.c b/drivers/i2c/busses/i2c-xgene-slimpro.c
index 63259b3ea5ab..bc9a3e7e0c96 100644
--- a/drivers/i2c/busses/i2c-xgene-slimpro.c
+++ b/drivers/i2c/busses/i2c-xgene-slimpro.c
@@ -391,6 +391,10 @@ static int xgene_slimpro_i2c_xfer(struct i2c_adapter *adap, u16 addr,
 						&data->block[0]);
 
 		} else {
+
+			if (data->block[0] + 1 > I2C_SMBUS_BLOCK_MAX)
+				return -EINVAL;
+
 			ret = slimpro_i2c_blkwr(ctx, addr, command,
 						SMBUS_CMD_LEN,
 						SLIMPRO_IIC_SMB_PROTOCOL,
@@ -408,6 +412,10 @@ static int xgene_slimpro_i2c_xfer(struct i2c_adapter *adap, u16 addr,
 						IIC_SMB_WITHOUT_DATA_LEN,
 						&data->block[1]);
 		} else {
+
+			if (data->block[0] > I2C_SMBUS_BLOCK_MAX)
+				return -EINVAL;
+
 			ret = slimpro_i2c_blkwr(ctx, addr, command,
 						SMBUS_CMD_LEN,
 						SLIMPRO_IIC_I2C_PROTOCOL,
-- 
2.25.1