[net-next] ipvs: Use struct_size() helper

Message ID 20190208004456.GA15845@embeddedor
State Accepted
Delegated to: Pablo Neira
Headers show
Series
  • [net-next] ipvs: Use struct_size() helper
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Commit Message

Gustavo A. R. Silva Feb. 8, 2019, 12:44 a.m.
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 = alloc(size, GFP_KERNEL)

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

size = struct_size(instance, entry, count);

This code was detected with the help of Coccinelle.

Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
---
 net/netfilter/ipvs/ip_vs_ctl.c | 6 ++----
 1 file changed, 2 insertions(+), 4 deletions(-)

Comments

Simon Horman Feb. 8, 2019, 9:56 a.m. | #1
On Thu, Feb 07, 2019 at 06:44:56PM -0600, 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;
>     struct boo entry[];
> };
> 
> size = sizeof(struct foo) + count * sizeof(struct boo);
> instance = alloc(size, GFP_KERNEL)
> 
> Instead of leaving these open-coded and prone to type mistakes, we can
> now use the new struct_size() helper:
> 
> size = struct_size(instance, entry, count);
> 
> This code was detected with the help of Coccinelle.
> 
> Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>

Acked-by: Simon Horman <horms+renesas@verge.net.au>

Pablo, could you consider applying this?

> ---
>  net/netfilter/ipvs/ip_vs_ctl.c | 6 ++----
>  1 file changed, 2 insertions(+), 4 deletions(-)
> 
> diff --git a/net/netfilter/ipvs/ip_vs_ctl.c b/net/netfilter/ipvs/ip_vs_ctl.c
> index 7d6318664eb2..bcd9112f47d9 100644
> --- a/net/netfilter/ipvs/ip_vs_ctl.c
> +++ b/net/netfilter/ipvs/ip_vs_ctl.c
> @@ -2734,8 +2734,7 @@ do_ip_vs_get_ctl(struct sock *sk, int cmd, void __user *user, int *len)
>  		int size;
>  
>  		get = (struct ip_vs_get_services *)arg;
> -		size = sizeof(*get) +
> -			sizeof(struct ip_vs_service_entry) * get->num_services;
> +		size = struct_size(get, entrytable, get->num_services);
>  		if (*len != size) {
>  			pr_err("length: %u != %u\n", *len, size);
>  			ret = -EINVAL;
> @@ -2776,8 +2775,7 @@ do_ip_vs_get_ctl(struct sock *sk, int cmd, void __user *user, int *len)
>  		int size;
>  
>  		get = (struct ip_vs_get_dests *)arg;
> -		size = sizeof(*get) +
> -			sizeof(struct ip_vs_dest_entry) * get->num_dests;
> +		size = struct_size(get, entrytable, get->num_dests);
>  		if (*len != size) {
>  			pr_err("length: %u != %u\n", *len, size);
>  			ret = -EINVAL;
> -- 
> 2.20.1
>
Pablo Neira Ayuso Feb. 11, 2019, 11:40 p.m. | #2
On Fri, Feb 08, 2019 at 10:56:48AM +0100, Simon Horman wrote:
> On Thu, Feb 07, 2019 at 06:44:56PM -0600, 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;
> >     struct boo entry[];
> > };
> > 
> > size = sizeof(struct foo) + count * sizeof(struct boo);
> > instance = alloc(size, GFP_KERNEL)
> > 
> > Instead of leaving these open-coded and prone to type mistakes, we can
> > now use the new struct_size() helper:
> > 
> > size = struct_size(instance, entry, count);
> > 
> > This code was detected with the help of Coccinelle.
> > 
> > Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
> 
> Acked-by: Simon Horman <horms+renesas@verge.net.au>
> 
> Pablo, could you consider applying this?

Applied, thanks!
Gustavo A. R. Silva Feb. 12, 2019, 1:47 a.m. | #3
On 2/11/19 5:40 PM, Pablo Neira Ayuso wrote:
> On Fri, Feb 08, 2019 at 10:56:48AM +0100, Simon Horman wrote:
>> On Thu, Feb 07, 2019 at 06:44:56PM -0600, 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;
>>>     struct boo entry[];
>>> };
>>>
>>> size = sizeof(struct foo) + count * sizeof(struct boo);
>>> instance = alloc(size, GFP_KERNEL)
>>>
>>> Instead of leaving these open-coded and prone to type mistakes, we can
>>> now use the new struct_size() helper:
>>>
>>> size = struct_size(instance, entry, count);
>>>
>>> This code was detected with the help of Coccinelle.
>>>
>>> Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
>>
>> Acked-by: Simon Horman <horms+renesas@verge.net.au>
>>
>> Pablo, could you consider applying this?
> 
> Applied, thanks!
> 

Thank you both, Simon and Pablo.

--
Gustavo

Patch

diff --git a/net/netfilter/ipvs/ip_vs_ctl.c b/net/netfilter/ipvs/ip_vs_ctl.c
index 7d6318664eb2..bcd9112f47d9 100644
--- a/net/netfilter/ipvs/ip_vs_ctl.c
+++ b/net/netfilter/ipvs/ip_vs_ctl.c
@@ -2734,8 +2734,7 @@  do_ip_vs_get_ctl(struct sock *sk, int cmd, void __user *user, int *len)
 		int size;
 
 		get = (struct ip_vs_get_services *)arg;
-		size = sizeof(*get) +
-			sizeof(struct ip_vs_service_entry) * get->num_services;
+		size = struct_size(get, entrytable, get->num_services);
 		if (*len != size) {
 			pr_err("length: %u != %u\n", *len, size);
 			ret = -EINVAL;
@@ -2776,8 +2775,7 @@  do_ip_vs_get_ctl(struct sock *sk, int cmd, void __user *user, int *len)
 		int size;
 
 		get = (struct ip_vs_get_dests *)arg;
-		size = sizeof(*get) +
-			sizeof(struct ip_vs_dest_entry) * get->num_dests;
+		size = struct_size(get, entrytable, get->num_dests);
 		if (*len != size) {
 			pr_err("length: %u != %u\n", *len, size);
 			ret = -EINVAL;