Commit 5ebf5c89 authored Feb 18, 2019 by Gustavo A. R. Silva Committed by Greg Kroah-Hartman Feb 19, 2019

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>

parent eeca7606

drivers/usb/core/config.c

+3 −3

Original line number	Diff line number	Diff line
		@@ -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);

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