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

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

This only finds one hit in the entire tree, but here's the Coccinelle:

// Directly refer to structure's field
@@
identifier alloc =~ "vmalloc|vzalloc";
identifier VAR, ELEMENT;
expression COUNT;
@@

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

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

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

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

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

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