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@xxxxxxxxxxxxxx>
---
drivers/usb/core/urb.c | 5 ++---
1 file changed, 2 insertions(+), 3 deletions(-)
diff --git a/drivers/usb/core/urb.c b/drivers/usb/core/urb.c
index f51750bcd152..0eab79f82ce4 100644
--- a/drivers/usb/core/urb.c
+++ b/drivers/usb/core/urb.c
@@ -70,9 +70,8 @@ struct urb *usb_alloc_urb(int iso_packets, gfp_t mem_flags)
{
struct urb *urb;
- urb = kmalloc(sizeof(struct urb) +
- iso_packets * sizeof(struct usb_iso_packet_descriptor),
- mem_flags);
+ urb = kmalloc(struct_size(urb, iso_frame_desc, iso_packets),
+ mem_flags);
if (!urb)
return NULL;
usb_init_urb(urb);
--
2.20.1
