[PATCH 4.19 47/58] kernel: module: Use struct_size() helper

[Greg Kroah-Hartman]

From: Gustavo A. R. Silva <gust...@embeddedor.com>

commit 8d1b73dd25ff92c3fa9807a20c22fa2b44c07336 upstream.

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 module_sect_attrs {
        ...
        struct module_sect_attr attrs[0];
};

Make use of the struct_size() helper instead of an open-coded version
in order to avoid any potential type mistakes.

So, replace the following form:

sizeof(*sect_attrs) + nloaded * sizeof(sect_attrs->attrs[0]

with:

struct_size(sect_attrs, attrs, nloaded)

This code was detected with the help of Coccinelle.

Signed-off-by: Gustavo A. R. Silva <gust...@embeddedor.com>
Signed-off-by: Jessica Yu <j...@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gre...@linuxfoundation.org>

---
 kernel/module.c |    3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

--- a/kernel/module.c
+++ b/kernel/module.c
@@ -1491,8 +1491,7 @@ static void add_sect_attrs(struct module
        for (i = 0; i < info->hdr->e_shnum; i++)
                if (!sect_empty(&info->sechdrs[i]))
                        nloaded++;
-       size[0] = ALIGN(sizeof(*sect_attrs)
-                       + nloaded * sizeof(sect_attrs->attrs[0]),
+       size[0] = ALIGN(struct_size(sect_attrs, attrs, nloaded),
                        sizeof(sect_attrs->grp.attrs[0]));
        size[1] = (nloaded + 1) * sizeof(sect_attrs->grp.attrs[0]);
        sect_attrs = kzalloc(size[0] + size[1], GFP_KERNEL);