| Message ID | 20190108152225.GA5721@embeddedor (mailing list archive) |
|---|---|
| State | Mainlined |
| Commit | 6756f4c375db11af7039985636bddde676615a94 |
| Headers | show |
| Series | USB: core: urb: Use struct_size() in kmalloc() | expand |
On Tue, 8 Jan 2019, Gustavo A. R. Silva wrote: > 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@embeddedor.com> > --- > 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); Acked-by: Alan Stern <stern@rowland.harvard.edu>
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);
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@embeddedor.com> --- drivers/usb/core/urb.c | 5 ++--- 1 file changed, 2 insertions(+), 3 deletions(-)