pid: use struct_size_t() helper

Before commit d67790d ("overflow: Add struct_size_t() helper") only struct_size() existed, which expects a valid pointer instance containing the flexible array. However, when we determine the default struct pid allocation size for the associated kmem cache of a pid namespace we need to take the nesting depth of the pid namespace into account without an variable instance necessarily being available. In commit b69f0ae ("pid: Replace struct pid 1-element array with flex-array") we used to handle this the old fashioned way and cast NULL to a struct pid pointer type. However, we do apparently have a dedicated struct_size_t() helper for exactly this case. So switch to that. Suggested-by: Kees Cook <[email protected]> Suggested-by: Linus Torvalds <[email protected]> Signed-off-by: Christian Brauner <[email protected]> Signed-off-by: Linus Torvalds <[email protected]>
torvalds · Jul 1, 2023 · dd54661 · dd54661
1 parent 408579c
commit dd54661
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Showing 2 changed files with 2 additions and 2 deletions.
diff --git a/kernel/pid.c b/kernel/pid.c
@@ -657,7 +657,7 @@ void __init pid_idr_init(void)
  idr_init(&init_pid_ns.idr);
 
  init_pid_ns.pid_cachep = kmem_cache_create("pid",
- struct_size((struct pid *)NULL, numbers, 1),
+ struct_size_t(struct pid, numbers, 1),
  __alignof__(struct pid),
  SLAB_HWCACHE_ALIGN | SLAB_PANIC | SLAB_ACCOUNT,
  NULL);

diff --git a/kernel/pid_namespace.c b/kernel/pid_namespace.c
@@ -48,7 +48,7 @@ static struct kmem_cache *create_pid_cachep(unsigned int level)
  return kc;
 
  snprintf(name, sizeof(name), "pid_%u", level + 1);
- len = struct_size((struct pid *)NULL, numbers, level + 1);
+ len = struct_size_t(struct pid, numbers, level + 1);
  mutex_lock(&pid_caches_mutex);
  /* Name collision forces to do allocation under mutex. */
  if (!*pkc)