[PATCH] ubifs: super: Use struct_size() helper

From: "Gustavo A. R. Silva" <gustavo@embeddedor.com>
To: Richard Weinberger <richard@nod.at>,
	Artem Bityutskiy <dedekind1@gmail.com>,
	Adrian Hunter <adrian.hunter@intel.com>
Cc: linux-mtd@lists.infradead.org, linux-kernel@vger.kernel.org,
	"Gustavo A. R. Silva" <gustavo@embeddedor.com>
Subject: [PATCH] ubifs: super: Use struct_size() helper
Date: Wed, 28 Aug 2019 19:50:09 -0500	[thread overview]
Message-ID: <20190829005009.GA5895@embeddedor> (raw)

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 ubifs_znode {
	...
        struct ubifs_zbranch zbranch[];
};

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(struct ubifs_znode) + c->fanout * sizeof(struct ubifs_zbranch)

with:

struct_size(c->cnext, zbranch, c->fanout)

This code was detected with the help of Coccinelle.

Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
---
 fs/ubifs/super.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/fs/ubifs/super.c b/fs/ubifs/super.c
index 2706f13e3eb9..ca86489048c8 100644
--- a/fs/ubifs/super.c
+++ b/fs/ubifs/super.c
@@ -661,8 +661,7 @@ static int init_constants_sb(struct ubifs_info *c)
 	long long tmp64;
 
 	c->main_bytes = (long long)c->main_lebs * c->leb_size;
-	c->max_znode_sz = sizeof(struct ubifs_znode) +
-				c->fanout * sizeof(struct ubifs_zbranch);
+	c->max_znode_sz = struct_size(c->cnext, zbranch, c->fanout);
 
 	tmp = ubifs_idx_node_sz(c, 1);
 	c->ranges[UBIFS_IDX_NODE].min_len = tmp;
-- 
2.23.0


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