linux-kernel - [PATCH] mtd: gen_probe: Use struct

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Date:   Tue, 8 Jan 2019 09:36:01 -0600
From:   "Gustavo A. R. Silva" <gustavo@...eddedor.com>
To:     David Woodhouse <dwmw2@...radead.org>,
        Brian Norris <computersforpeace@...il.com>,
        Boris Brezillon <bbrezillon@...nel.org>,
        Marek Vasut <marek.vasut@...il.com>,
        Richard Weinberger <richard@....at>
Cc:     linux-mtd@...ts.infradead.org, linux-kernel@...r.kernel.org,
        "Gustavo A. R. Silva" <gustavo@...eddedor.com>
Subject: [PATCH] mtd: gen_probe: Use struct_size() in kmalloc()

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 code was detected with the help of Coccinelle.

Signed-off-by: Gustavo A. R. Silva <gustavo@...eddedor.com>
---
 drivers/mtd/chips/gen_probe.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/mtd/chips/gen_probe.c b/drivers/mtd/chips/gen_probe.c
index 837b04ab96a9..839ed40625d6 100644
--- a/drivers/mtd/chips/gen_probe.c
+++ b/drivers/mtd/chips/gen_probe.c
@@ -135,7 +135,7 @@ static struct cfi_private *genprobe_ident_chips(struct map_info *map, struct chi
 	 * our caller, and copy the appropriate data into them.
 	 */
 
-	retcfi = kmalloc(sizeof(struct cfi_private) + cfi.numchips * sizeof(struct flchip), GFP_KERNEL);
+	retcfi = kmalloc(struct_size(retcfi, chips, cfi.numchips), GFP_KERNEL);
 
 	if (!retcfi) {
 		kfree(cfi.cfiq);
-- 
2.20.1