Commit 67b8046f authored Mar 05, 2019 by Gustavo A. R. Silva Committed by Linus Torvalds Mar 05, 2019

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@embeddedor.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Vladimir Davydov <vdavydov.dev@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

parent c52e7593

mm/memcontrol.c

+1 −2

Original line number	Original line	Diff line number	Diff line
	@@ -3626,8 +3626,7 @@ static int __mem_cgroup_usage_register_event(struct mem_cgroup *memcg,
	size = thresholds->primary ? thresholds->primary->size + 1 : 1;		size = thresholds->primary ? thresholds->primary->size + 1 : 1;

	/* Allocate memory for new array of thresholds */		/* Allocate memory for new array of thresholds */
	new = kmalloc(sizeof(new) + size sizeof(struct mem_cgroup_threshold),		new = kmalloc(struct_size(new, entries, size), GFP_KERNEL);
	GFP_KERNEL);
	if (!new) {		if (!new) {
	ret = -ENOMEM;		ret = -ENOMEM;
	goto unlock;		goto unlock;

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