From: "Gustavo A. R. Silva" <gustavo@xxxxxxxxxxxxxx>
Subject: mm/swapfile.c: use struct_size() in kvzalloc()
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;
struct boo entry[];
};
size = sizeof(struct foo) + count * sizeof(struct boo);
instance = kvzalloc(size, GFP_KERNEL);
Instead of leaving these open-coded and prone to type mistakes, we can
now use the new struct_size() helper:
instance = kvzalloc(struct_size(instance, entry, count), GFP_KERNEL);
Notice that, in this case, variable size is not necessary, hence
it is removed.
This code was detected with the help of Coccinelle.
Link: http://lkml.kernel.org/r/20190221154622.GA19599@embeddedor
Signed-off-by: Gustavo A. R. Silva <gustavo@xxxxxxxxxxxxxx>
Reviewed-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/swapfile.c | 3 +--
1 file changed, 1 insertion(+), 2 deletions(-)
--- a/mm/swapfile.c~mm-swapfilec-use-struct_size-in-kvzalloc
+++ a/mm/swapfile.c
@@ -2713,9 +2713,8 @@ static struct swap_info_struct *alloc_sw
struct swap_info_struct *p;
unsigned int type;
int i;
- unsigned int size = sizeof(*p) + nr_node_ids * sizeof(struct plist_node);
- p = kvzalloc(size, GFP_KERNEL);
+ p = kvzalloc(struct_size(p, avail_lists, nr_node_ids), GFP_KERNEL);
if (!p)
return ERR_PTR(-ENOMEM);
_
