[PATCH] drivers: qcom: rpmh: use struct_size() in kzalloc()

From: Gustavo A. R. Silva
Date: Mon Dec 24 2018 - 01:22:52 EST

One of the more common cases of allocation size calculations is finding
the size of a structure that has a zero-sized array at the end, along
with memory for some number of elements for that array. For example:

struct foo {
int stuff;
void *entry[];

instance = kzalloc(sizeof(struct foo) + sizeof(void *) * count, GFP_KERNEL);

Instead of leaving these open-coded and prone to type mistakes, we can
now use the new struct_size() helper:

instance = kzalloc(struct_size(instance, entry, count), GFP_KERNEL);

This issue was detected with the help of Coccinelle.

Signed-off-by: Gustavo A. R. Silva <gustavo@xxxxxxxxxxxxxx>
drivers/soc/qcom/rpmh.c | 3 +--
1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/drivers/soc/qcom/rpmh.c b/drivers/soc/qcom/rpmh.c
index c7beb6841289..12c057a0b325 100644
--- a/drivers/soc/qcom/rpmh.c
+++ b/drivers/soc/qcom/rpmh.c
@@ -362,8 +362,7 @@ int rpmh_write_batch(const struct device *dev, enum rpmh_state state,
if (!count)
return -EINVAL;

- req = kzalloc(sizeof(*req) + count * sizeof(req->rpm_msgs[0]),
+ req = kzalloc(struct_size(req, rpm_msgs, count), GFP_ATOMIC);
if (!req)
return -ENOMEM;
req->count = count;