ipv4: fib: use struct_size() in kzalloc()

GustavoARSilva · davem330 · commit 1f533ba6d50d · 2019-02-01T15:12:29.000-08:00
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[];
};

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

This code was detected with the help of Coccinelle.

Signed-off-by: Gustavo A. R. Silva &lt;gustavo@embeddedor.com&gt;
Signed-off-by: David S. Miller &lt;davem@davemloft.net&gt;
diff --git a/net/ipv4/fib_semantics.c b/net/ipv4/fib_semantics.c
@@ -1072,7 +1072,7 @@ struct fib_info *fib_create_info(struct fib_config *cfg,
 			goto failure;
 	}
 
-	fi = kzalloc(sizeof(*fi)+nhs*sizeof(struct fib_nh), GFP_KERNEL);
+	fi = kzalloc(struct_size(fi, fib_nh, nhs), GFP_KERNEL);
 	if (!fi)
 		goto failure;
 	fi->fib_metrics = ip_fib_metrics_init(fi->fib_net, cfg->fc_mx,

Original file line number	Diff line number	Diff line change
`@@ -1072,7 +1072,7 @@ struct fib_info fib_create_info(struct fib_config cfg,`
`1072`	`1072`	`goto failure;`
`1073`	`1073`	`}`
`1074`	`1074`
`1075`		`- fi = kzalloc(sizeof(fi)+nhssizeof(struct fib_nh), GFP_KERNEL);`
	`1075`	`+ fi = kzalloc(struct_size(fi, fib_nh, nhs), GFP_KERNEL);`
`1076`	`1076`	`if (!fi)`
`1077`	`1077`	`goto failure;`
`1078`	`1078`	`fi->fib_metrics = ip_fib_metrics_init(fi->fib_net, cfg->fc_mx,`