[PATCH][next] staging: greybus: i2c: Use struct_size() helper in gb_i2c_operation_create()

["Gustavo A. R. Silva" <gustavoars@kernel.org>]

Make use of the struct_size() helper instead of an open-coded version,
in order to avoid any potential type mistakes or integer overflows that,
in the worst scenario, could lead to heap overflows.

Also, address the following sparse warnings:
drivers/staging/greybus/i2c.c:111:24: warning: using sizeof on a flexible structure

Link: https://github.com/KSPP/linux/issues/174
Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>
---
 drivers/staging/greybus/i2c.c | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/drivers/staging/greybus/i2c.c b/drivers/staging/greybus/i2c.c
index de2f6516da09..9dfc6791c20e 100644
--- a/drivers/staging/greybus/i2c.c
+++ b/drivers/staging/greybus/i2c.c
@@ -108,9 +108,7 @@ gb_i2c_operation_create(struct gb_connection *connection,
 		else
 			data_out_size += (u32)msg->len;
 
-	request_size = sizeof(*request);
-	request_size += msg_count * sizeof(*op);
-	request_size += data_out_size;
+	request_size = struct_size(request, ops, msg_count) + data_out_size;
 
 	/* Response consists only of incoming data */
 	operation = gb_operation_create(connection, GB_I2C_TYPE_TRANSFER,
-- 
2.27.0