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 <[email protected]>
---
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
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 <[email protected]>
Acked-by: Simon Horman <[email protected]>
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
>
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 <[email protected]>
>
> Acked-by: Simon Horman <[email protected]>
>
> Pablo, could you consider applying this?
Applied, thanks!
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 <[email protected]>
>>
>> Acked-by: Simon Horman <[email protected]>
>>
>> Pablo, could you consider applying this?
>
> Applied, thanks!
>
Thank you both, Simon and Pablo.
--
Gustavo