treewide: Use struct_size() for kmalloc()-family

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 patch makes the changes for kmalloc()-family (and kvmalloc()-family)
uses. It was done via automatic conversion with manual review for the
"CHECKME" non-standard cases noted below, using the following Coccinelle
script:

// pkey_cache = kmalloc(sizeof *pkey_cache + tprops->pkey_tbl_len *
//                      sizeof *pkey_cache->table, GFP_KERNEL);
@@
identifier alloc =~ "kmalloc|kzalloc|kvmalloc|kvzalloc";
expression GFP;
identifier VAR, ELEMENT;
expression COUNT;
@@

- alloc(sizeof(*VAR) + COUNT * sizeof(*VAR->ELEMENT), GFP)
+ alloc(struct_size(VAR, ELEMENT, COUNT), GFP)

// mr = kzalloc(sizeof(*mr) + m * sizeof(mr->map[0]), GFP_KERNEL);
@@
identifier alloc =~ "kmalloc|kzalloc|kvmalloc|kvzalloc";
expression GFP;
identifier VAR, ELEMENT;
expression COUNT;
@@

- alloc(sizeof(*VAR) + COUNT * sizeof(VAR->ELEMENT[0]), GFP)
+ alloc(struct_size(VAR, ELEMENT, COUNT), GFP)

// Same pattern, but can't trivially locate the trailing element name,
// or variable name.
@@
identifier alloc =~ "kmalloc|kzalloc|kvmalloc|kvzalloc";
expression GFP;
expression SOMETHING, COUNT, ELEMENT;
@@

- alloc(sizeof(SOMETHING) + COUNT * sizeof(ELEMENT), GFP)
+ alloc(CHECKME_struct_size(&SOMETHING, ELEMENT, COUNT), GFP)

Signed-off-by: Kees Cook <keescook@chromium.org>

1 files changed, 10 insertions, 11 deletions

diff --git a/drivers/infiniband/core/uverbs_ioctl_merge.c b/drivers/infiniband/core/uverbs_ioctl_merge.c
index 0f88a1919d51..6ceb672c4d46 100644
--- a/drivers/infiniband/core/uverbs_ioctl_merge.c
+++ b/drivers/infiniband/core/uverbs_ioctl_merge.c
@@ -297,8 +297,7 @@ static struct uverbs_method_spec *build_method_with_attrs(const struct uverbs_me
 	if (max_attr_buckets >= 0)
 		num_attr_buckets = max_attr_buckets + 1;
 
-	method = kzalloc(sizeof(*method) +
-			 num_attr_buckets * sizeof(*method->attr_buckets),
+	method = kzalloc(struct_size(method, attr_buckets, num_attr_buckets),
 			 GFP_KERNEL);
 	if (!method)
 		return ERR_PTR(-ENOMEM);
@@ -446,9 +445,9 @@ static struct uverbs_object_spec *build_object_with_methods(const struct uverbs_
 	if (max_method_buckets >= 0)
 		num_method_buckets = max_method_buckets + 1;
 
-	object = kzalloc(sizeof(*object) +
-			 num_method_buckets *
-			 sizeof(*object->method_buckets), GFP_KERNEL);
+	object = kzalloc(struct_size(object, method_buckets,
+				     num_method_buckets),
+			 GFP_KERNEL);
 	if (!object)
 		return ERR_PTR(-ENOMEM);
 
@@ -469,8 +468,8 @@ static struct uverbs_object_spec *build_object_with_methods(const struct uverbs_
 		if (methods_max_bucket < 0)
 			continue;
 
-		hash = kzalloc(sizeof(*hash) +
-			       sizeof(*hash->methods) * (methods_max_bucket + 1),
+		hash = kzalloc(struct_size(hash, methods,
+					   methods_max_bucket + 1),
 			       GFP_KERNEL);
 		if (!hash) {
 			res = -ENOMEM;
@@ -579,8 +578,8 @@ struct uverbs_root_spec *uverbs_alloc_spec_tree(unsigned int num_trees,
 	if (max_object_buckets >= 0)
 		num_objects_buckets = max_object_buckets + 1;
 
-	root_spec = kzalloc(sizeof(*root_spec) +
-			    num_objects_buckets * sizeof(*root_spec->object_buckets),
+	root_spec = kzalloc(struct_size(root_spec, object_buckets,
+					num_objects_buckets),
 			    GFP_KERNEL);
 	if (!root_spec)
 		return ERR_PTR(-ENOMEM);
@@ -603,8 +602,8 @@ struct uverbs_root_spec *uverbs_alloc_spec_tree(unsigned int num_trees,
 		if (objects_max_bucket < 0)
 			continue;
 
-		hash = kzalloc(sizeof(*hash) +
-			       sizeof(*hash->objects) * (objects_max_bucket + 1),
+		hash = kzalloc(struct_size(hash, objects,
+					   objects_max_bucket + 1),
 			       GFP_KERNEL);
 		if (!hash) {
 			res = -ENOMEM;