From: "Gustavo A. R. Silva" <gustavo@xxxxxxxxxxxxxx>
Subject: mm/memcontrol.c: use struct_size() in kmalloc()
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 = kmalloc(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 = kmalloc(struct_size(instance, entry, count), GFP_KERNEL);
This code was detected with the help of Coccinelle.
Link: http://lkml.kernel.org/r/20190104183726.GA6374@embeddedor
Signed-off-by: Gustavo A. R. Silva <gustavo@xxxxxxxxxxxxxx>
Acked-by: Michal Hocko <mhocko@xxxxxxxx>
Cc: Johannes Weiner <hannes@xxxxxxxxxxx>
Cc: Vladimir Davydov <vdavydov.dev@xxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/memcontrol.c | 3 +--
1 file changed, 1 insertion(+), 2 deletions(-)
--- a/mm/memcontrol.c~mm-memcontrol-use-struct_size-in-kmalloc
+++ a/mm/memcontrol.c
@@ -3626,8 +3626,7 @@ static int __mem_cgroup_usage_register_e
size = thresholds->primary ? thresholds->primary->size + 1 : 1;
/* Allocate memory for new array of thresholds */
- new = kmalloc(sizeof(*new) + size * sizeof(struct mem_cgroup_threshold),
- GFP_KERNEL);
+ new = kmalloc(struct_size(new, entries, size), GFP_KERNEL);
if (!new) {
ret = -ENOMEM;
goto unlock;
_
