[PATCH] usb: core: config: Use struct_size() in kzalloc()
From: Gustavo A. R. Silva
Date: Mon Feb 18 2019 - 14:06:46 EST
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@xxxxxxxxxxxxxx>
---
drivers/usb/core/config.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)
diff --git a/drivers/usb/core/config.c b/drivers/usb/core/config.c
index 7bb6b1bd06c8..20ff036b4c22 100644
--- a/drivers/usb/core/config.c
+++ b/drivers/usb/core/config.c
@@ -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);
--
2.20.1