mtd: cfi: cmdset_0001: 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.

---
 drivers/mtd/chips/cfi_cmdset_0001.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

index 6e8e7b1bb34b..79a53cb8507b 100644
@@ -756,7 +756,8 @@ static int cfi_intelext_partition_fixup(struct mtd_info *mtd,
 		}
 
 		numvirtchips = cfi->numchips * numparts;
-		newcfi = kmalloc(sizeof(struct cfi_private) + numvirtchips * sizeof(struct flchip), GFP_KERNEL);
+		newcfi = kmalloc(struct_size(newcfi, chips, numvirtchips),
+				 GFP_KERNEL);
 		if (!newcfi)
 			return -ENOMEM;
 		shared = kmalloc_array(cfi->numchips,

2.20.1

From: Boris Brezillon <[email protected]>

Applied to http://git.infradead.org/linux-mtd.git mtd/next, thanks.

Boris