i2c: mlxbf: prevent stack overflow in mlxbf_i2c_smbus_start_transaction()

memcpy() is called in a loop while 'operation->length' upper bound
is not checked and 'data_idx' also increments.

Fixes: b5b5b32 ("i2c: mlxbf: I2C SMBus driver for Mellanox BlueField SoC")
Reviewed-by: Khalil Blaiech <kblaiech@nvidia.com>
Signed-off-by: Asmaa Mnebhi <asmaa@nvidia.com>
Signed-off-by: Wolfram Sang <wsa@kernel.org>

Author: Asmaa Mnebhi

drivers/i2c/busses/i2c-mlxbf.c

@@ -738,6 +738,9 @@ mlxbf_i2c_smbus_start_transaction(struct mlxbf_i2c_priv *priv,
 		if (flags & MLXBF_I2C_F_WRITE) {
 			write_en = 1;
 			write_len += operation->length;
+			if (data_idx + operation->length >
+					MLXBF_I2C_MASTER_DATA_DESC_SIZE)
+				return -ENOBUFS;
 			memcpy(data_desc + data_idx,
 			       operation->buffer, operation->length);
 			data_idx += operation->length;