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usb: core: config: Use struct_size() in kzalloc() 

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;
    struct boo entry[];
};

size = sizeof(struct foo) + count * sizeof(struct boo);
instance = kzalloc(size, GFP_KERNEL);

Instead of leaving these open-coded and prone to type mistakes, we can
now use the new struct_size() helper:

instance = kzalloc(struct_size(instance, entry, count), GFP_KERNEL);

Notice that, in this case, variable len is not necessary, hence
it is removed.

This code was detected with the help of Coccinelle.

Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Gustavo A. R. Silva 2019-02-18 13:06:41 -06:00 committed by Greg Kroah-Hartman
parent eeca7606dd
commit 5ebf5c8903
1 changed files with 3 additions and 3 deletions
drivers/usb/core
config.c

6
drivers/usb/core/config.c
View File

@ -552,7 +552,7 @@ static int usb_parse_configuration(struct usb_device *dev, int cfgidx,
unsigned char *buffer2;
int size2;
struct usb_descriptor_header *header;
int len, retval;
int retval;
u8 inums[USB_MAXINTERFACES], nalts[USB_MAXINTERFACES];
unsigned iad_num = 0;
@ -707,8 +707,8 @@ static int usb_parse_configuration(struct usb_device *dev, int cfgidx,
nalts[i] = j = USB_MAXALTSETTING;
}
len = sizeof(*intfc) + sizeof(struct usb_host_interface) * j;
config->intf_cache[i] = intfc = kzalloc(len, GFP_KERNEL);
intfc = kzalloc(struct_size(intfc, altsetting, j), GFP_KERNEL);
config->intf_cache[i] = intfc;
if (!intfc)
return -ENOMEM;
kref_init(&intfc->ref);