From: "Gustavo A. R. Silva" <gustavoars@xxxxxxxxxx> Subject: mm: memcontrol: use flex_array_size() helper in memcpy() Make use of the flex_array_size() helper to calculate the size of a flexible array member within an enclosing structure. This helper offers defense-in-depth against potential integer overflows, while at the same time makes it explicitly clear that we are dealing with a flexible array member. Also, remove unnecessary braces. Link: https://lkml.kernel.org/r/ddd60dae2d9aea1ccdd2be66634815c93696125e.1596214831.git.gustavoars@xxxxxxxxxx Signed-off-by: Gustavo A. R. Silva <gustavoars@xxxxxxxxxx> 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 | 7 +++---- 1 file changed, 3 insertions(+), 4 deletions(-) --- a/mm/memcontrol.c~mm-memcontrol-use-flex_array_size-helper-in-memcpy +++ a/mm/memcontrol.c @@ -4255,10 +4255,9 @@ static int __mem_cgroup_usage_register_e new->size = size; /* Copy thresholds (if any) to new array */ - if (thresholds->primary) { - memcpy(new->entries, thresholds->primary->entries, (size - 1) * - sizeof(struct mem_cgroup_threshold)); - } + if (thresholds->primary) + memcpy(new->entries, thresholds->primary->entries, + flex_array_size(new, entries, size - 1)); /* Add new threshold */ new->entries[size - 1].eventfd = eventfd; _
