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.

---
 drivers/mtd/chips/gen_probe.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

index 837b04ab96a9..839ed40625d6 100644
@@ -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

From: Boris Brezillon <[email protected]>

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

Boris