From e90342e6d26ab6d1c38c8f5804492d76e3e9b4e9 Mon Sep 17 00:00:00 2001
From: "Gustavo A. R. Silva" <gustavoars@kernel.org>
Date: Tue, 13 Oct 2020 16:52:36 -0700
Subject: [PATCH] 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.
Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Vladimir Davydov <vdavydov.dev@gmail.com>
Link: https://lkml.kernel.org/r/ddd60dae2d9aea1ccdd2be66634815c93696125e.1596214831.git.gustavoars@kernel.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---
mm/memcontrol.c | 7 +++----
1 file changed, 3 insertions(+), 4 deletions(-)
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index d8bdbe1e8ff82..e3565ec024013 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -4255,10 +4255,9 @@ static int __mem_cgroup_usage_register_event(struct mem_cgroup *memcg,
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;
--
2.30.2