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.

Link: https://github.com/KSPP/linux/issues/160
Signed-off-by: Wang Weiyang <wangweiyang2@huawei.com>
---
 mm/memcontrol.c | 6 +-----
 1 file changed, 1 insertion(+), 5 deletions(-)

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 54afa29145e8..ec4b677cdcad 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -5129,15 +5129,11 @@ static void mem_cgroup_free(struct mem_cgroup *memcg)
 static struct mem_cgroup *mem_cgroup_alloc(void)
 {
 	struct mem_cgroup *memcg;
-	unsigned int size;
 	int node;
 	int __maybe_unused i;
 	long error = -ENOMEM;
 
-	size = sizeof(struct mem_cgroup);
-	size += nr_node_ids * sizeof(struct mem_cgroup_per_node *);
-
-	memcg = kzalloc(size, GFP_KERNEL);
+	memcg = kzalloc(struct_size(memcg, nodeinfo, nr_node_ids), GFP_KERNEL);
 	if (!memcg)
 		return ERR_PTR(error);
 
-- 
2.17.1

On Thu, Dec 16, 2021 at 10:21 AM Wang Weiyang <wangweiyang2@huawei.com> wrote:
>
> 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.
>
> Link: https://github.com/KSPP/linux/issues/160
> Signed-off-by: Wang Weiyang <wangweiyang2@huawei.com>

Reviewed-by: Muchun Song <songmuchun@bytedance.com>

On Thu, Dec 16, 2021 at 10:20:24AM +0800, Wang Weiyang wrote:
> 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.
> 
> Link: https://github.com/KSPP/linux/issues/160
> Signed-off-by: Wang Weiyang <wangweiyang2@huawei.com>

Acked-by: Johannes Weiner <hannes@cmpxchg.org>