* [PATCH] rtc: sun6i: Use struct_size() in kzalloc()
@ 2018-08-23 18:51 Gustavo A. R. Silva
2018-08-23 20:56 ` Kees Cook
` (2 more replies)
0 siblings, 3 replies; 5+ messages in thread
From: Gustavo A. R. Silva @ 2018-08-23 18:51 UTC (permalink / raw)
To: Alessandro Zummo, Alexandre Belloni, Maxime Ripard, Chen-Yu Tsai
Cc: linux-rtc, linux-arm-kernel, linux-kernel, Kees Cook,
Gustavo A. R. Silva
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;
void *entry[];
};
instance = kzalloc(sizeof(struct foo) + sizeof(void *) * count, 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);
Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
---
drivers/rtc/rtc-sun6i.c | 3 +--
1 file changed, 1 insertion(+), 2 deletions(-)
diff --git a/drivers/rtc/rtc-sun6i.c b/drivers/rtc/rtc-sun6i.c
index 2cd5a7b..fe07310 100644
--- a/drivers/rtc/rtc-sun6i.c
+++ b/drivers/rtc/rtc-sun6i.c
@@ -199,8 +199,7 @@ static void __init sun6i_rtc_clk_init(struct device_node *node)
if (!rtc)
return;
- clk_data = kzalloc(sizeof(*clk_data) + (sizeof(*clk_data->hws) * 2),
- GFP_KERNEL);
+ clk_data = kzalloc(struct_size(clk_data, hws, 2), GFP_KERNEL);
if (!clk_data) {
kfree(rtc);
return;
--
2.7.4
^ permalink raw reply related [flat|nested] 5+ messages in thread
* Re: [PATCH] rtc: sun6i: Use struct_size() in kzalloc()
2018-08-23 18:51 [PATCH] rtc: sun6i: Use struct_size() in kzalloc() Gustavo A. R. Silva
@ 2018-08-23 20:56 ` Kees Cook
2018-08-23 22:01 ` Gustavo A. R. Silva
2018-08-23 21:56 ` Kees Cook
2018-08-27 21:02 ` Alexandre Belloni
2 siblings, 1 reply; 5+ messages in thread
From: Kees Cook @ 2018-08-23 20:56 UTC (permalink / raw)
To: Gustavo A. R. Silva
Cc: Alessandro Zummo, Alexandre Belloni, Maxime Ripard, Chen-Yu Tsai,
linux-rtc, linux-arm-kernel, LKML
On Thu, Aug 23, 2018 at 11:51 AM, Gustavo A. R. Silva
<gustavo@embeddedor.com> 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;
> void *entry[];
> };
>
> instance = kzalloc(sizeof(struct foo) + sizeof(void *) * count, 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);
>
> Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
> ---
> drivers/rtc/rtc-sun6i.c | 3 +--
> 1 file changed, 1 insertion(+), 2 deletions(-)
>
> diff --git a/drivers/rtc/rtc-sun6i.c b/drivers/rtc/rtc-sun6i.c
> index 2cd5a7b..fe07310 100644
> --- a/drivers/rtc/rtc-sun6i.c
> +++ b/drivers/rtc/rtc-sun6i.c
> @@ -199,8 +199,7 @@ static void __init sun6i_rtc_clk_init(struct device_node *node)
> if (!rtc)
> return;
>
> - clk_data = kzalloc(sizeof(*clk_data) + (sizeof(*clk_data->hws) * 2),
> - GFP_KERNEL);
> + clk_data = kzalloc(struct_size(clk_data, hws, 2), GFP_KERNEL);
> if (!clk_data) {
> kfree(rtc);
> return;
This looks like entirely correct to me, but I'm surprised the
Coccinelle script didn't discover this. I guess the isomorphisms don't
cover the parenthesis?
-Kees
--
Kees Cook
Pixel Security
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH] rtc: sun6i: Use struct_size() in kzalloc()
2018-08-23 20:56 ` Kees Cook
@ 2018-08-23 22:01 ` Gustavo A. R. Silva
0 siblings, 0 replies; 5+ messages in thread
From: Gustavo A. R. Silva @ 2018-08-23 22:01 UTC (permalink / raw)
To: Kees Cook
Cc: Alessandro Zummo, Alexandre Belloni, Maxime Ripard, Chen-Yu Tsai,
linux-rtc, linux-arm-kernel, LKML
On 8/23/18 3:56 PM, Kees Cook wrote:
>>
>> - clk_data = kzalloc(sizeof(*clk_data) + (sizeof(*clk_data->hws) * 2),
>> - GFP_KERNEL);
>> + clk_data = kzalloc(struct_size(clk_data, hws, 2), GFP_KERNEL);
>> if (!clk_data) {
>> kfree(rtc);
>> return;
>
> This looks like entirely correct to me, but I'm surprised the
> Coccinelle script didn't discover this. I guess the isomorphisms don't
> cover the parenthesis?
>
Apparently.
If I manually remove the ()s, the cocci script successfully generates a patch.
--
Gustavo
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH] rtc: sun6i: Use struct_size() in kzalloc()
2018-08-23 18:51 [PATCH] rtc: sun6i: Use struct_size() in kzalloc() Gustavo A. R. Silva
2018-08-23 20:56 ` Kees Cook
@ 2018-08-23 21:56 ` Kees Cook
2018-08-27 21:02 ` Alexandre Belloni
2 siblings, 0 replies; 5+ messages in thread
From: Kees Cook @ 2018-08-23 21:56 UTC (permalink / raw)
To: Gustavo A. R. Silva
Cc: Alessandro Zummo, Alexandre Belloni, Maxime Ripard, Chen-Yu Tsai,
linux-rtc, linux-arm-kernel, LKML
On Thu, Aug 23, 2018 at 11:51 AM, Gustavo A. R. Silva
<gustavo@embeddedor.com> 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;
> void *entry[];
> };
>
> instance = kzalloc(sizeof(struct foo) + sizeof(void *) * count, 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);
>
> Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
> ---
> drivers/rtc/rtc-sun6i.c | 3 +--
> 1 file changed, 1 insertion(+), 2 deletions(-)
>
> diff --git a/drivers/rtc/rtc-sun6i.c b/drivers/rtc/rtc-sun6i.c
> index 2cd5a7b..fe07310 100644
> --- a/drivers/rtc/rtc-sun6i.c
> +++ b/drivers/rtc/rtc-sun6i.c
> @@ -199,8 +199,7 @@ static void __init sun6i_rtc_clk_init(struct device_node *node)
> if (!rtc)
> return;
>
> - clk_data = kzalloc(sizeof(*clk_data) + (sizeof(*clk_data->hws) * 2),
> - GFP_KERNEL);
> + clk_data = kzalloc(struct_size(clk_data, hws, 2), GFP_KERNEL);
> if (!clk_data) {
> kfree(rtc);
> return;
Reviewed-by: Kees Cook <keescook@chromium.org>
-Kees
--
Kees Cook
Pixel Security
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH] rtc: sun6i: Use struct_size() in kzalloc()
2018-08-23 18:51 [PATCH] rtc: sun6i: Use struct_size() in kzalloc() Gustavo A. R. Silva
2018-08-23 20:56 ` Kees Cook
2018-08-23 21:56 ` Kees Cook
@ 2018-08-27 21:02 ` Alexandre Belloni
2 siblings, 0 replies; 5+ messages in thread
From: Alexandre Belloni @ 2018-08-27 21:02 UTC (permalink / raw)
To: Gustavo A. R. Silva
Cc: Alessandro Zummo, Maxime Ripard, Chen-Yu Tsai, linux-rtc,
linux-arm-kernel, linux-kernel, Kees Cook
On 23/08/2018 13:51:40-0500, 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;
> void *entry[];
> };
>
> instance = kzalloc(sizeof(struct foo) + sizeof(void *) * count, 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);
>
> Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
> ---
> drivers/rtc/rtc-sun6i.c | 3 +--
> 1 file changed, 1 insertion(+), 2 deletions(-)
>
Applied, thanks.
--
Alexandre Belloni, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com
^ permalink raw reply [flat|nested] 5+ messages in thread
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2018-08-23 18:51 [PATCH] rtc: sun6i: Use struct_size() in kzalloc() Gustavo A. R. Silva
2018-08-23 20:56 ` Kees Cook
2018-08-23 22:01 ` Gustavo A. R. Silva
2018-08-23 21:56 ` Kees Cook
2018-08-27 21:02 ` Alexandre Belloni
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