linux-kernel - [PATCH 4.19 47/58] kernel: module: Use struct

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Date:   Tue, 14 Jul 2020 20:44:20 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org,
        "Gustavo A. R. Silva" <gustavo@...eddedor.com>,
        Jessica Yu <jeyu@...nel.org>
Subject: [PATCH 4.19 47/58] kernel: module: Use struct_size() helper

From: Gustavo A. R. Silva <gustavo@...eddedor.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 <gustavo@...eddedor.com>
Signed-off-by: Jessica Yu <jeyu@...nel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.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);