[PATCH] rtc: sun6i: Use struct_size() in kzalloc()

[PATCH] rtc: sun6i: Use struct_size() in kzalloc()

[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

[PATCH] rtc: sun6i: Use struct_size() in kzalloc()

[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

Re: [PATCH] rtc: sun6i: Use struct_size() in kzalloc()

[Kees Cook]

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

[PATCH] rtc: sun6i: Use struct_size() in kzalloc()

[Kees Cook]

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

[Cocci] [Fwd: Re: [PATCH] rtc: sun6i: Use struct_size() in kzalloc()]

[Kees Cook]

On Thu, Aug 23, 2018 at 2:48 PM, Joe Perches <joe@perches.com> wrote:
> Forwarding a question about coccinelle and isomorphisms from Kees Cook
>
> ---------- Forwarded message ----------
> From: Kees Cook <keescook@chromium.org>
> To: "Gustavo A. R. Silva" <gustavo@embeddedor.com>
> Cc: Alessandro Zummo <a.zummo@towertech.it>, Alexandre Belloni <alexandre.belloni@bootlin.com>, Maxime Ripard <maxime.ripard@bootlin.com>, Chen-Yu Tsai <wens@csie.org>, linux-rtc at vger.kernel.org, linux-arm-kernel <linux-arm-kernel@lists.infradead.org>, LKML <linux-kernel@vger.kernel.org>
> Bcc:
> Date: Thu, 23 Aug 2018 13:56:35 -0700
> Subject: Re: [PATCH] rtc: sun6i: Use struct_size() in kzalloc()
> 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?

I had this:

@@
identifier alloc =~
"kmalloc|kzalloc|kmalloc_node|kzalloc_node|vmalloc|vzalloc|kvmalloc|kvzalloc";
identifier VAR, ELEMENT;
expression COUNT;
@@

- alloc(sizeof(*VAR) + COUNT * sizeof(*VAR->ELEMENT)
+ alloc(struct_size(VAR, ELEMENT, COUNT)
  , ...)

But I needed to explicitly change the rule to:

(
- alloc(sizeof(*VAR) + COUNT * sizeof(*VAR->ELEMENT)
+ alloc(struct_size(VAR, ELEMENT, COUNT)
  , ...)
|
- alloc(sizeof(*VAR) + (COUNT * sizeof(*VAR->ELEMENT))
+ alloc(struct_size(VAR, ELEMENT, COUNT)
  , ...)
)

to add the ()s. I would expect arithmetic commutative expressions to
match? But I had to add parens?

-Kees

-- 
Kees Cook
Pixel Security

[Cocci] [Fwd: Re: [PATCH] rtc: sun6i: Use struct_size() in kzalloc()]

[Julia Lawall]

On Thu, 23 Aug 2018, Kees Cook wrote:

> On Thu, Aug 23, 2018 at 2:48 PM, Joe Perches <joe@perches.com> wrote:
> > Forwarding a question about coccinelle and isomorphisms from Kees Cook
> >
> > ---------- Forwarded message ----------
> > From: Kees Cook <keescook@chromium.org>
> > To: "Gustavo A. R. Silva" <gustavo@embeddedor.com>
> > Cc: Alessandro Zummo <a.zummo@towertech.it>, Alexandre Belloni <alexandre.belloni@bootlin.com>, Maxime Ripard <maxime.ripard@bootlin.com>, Chen-Yu Tsai <wens@csie.org>, linux-rtc at vger.kernel.org, linux-arm-kernel <linux-arm-kernel@lists.infradead.org>, LKML <linux-kernel@vger.kernel.org>
> > Bcc:
> > Date: Thu, 23 Aug 2018 13:56:35 -0700
> > Subject: Re: [PATCH] rtc: sun6i: Use struct_size() in kzalloc()
> > 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?
>
> I had this:
>
> @@
> identifier alloc =~
> "kmalloc|kzalloc|kmalloc_node|kzalloc_node|vmalloc|vzalloc|kvmalloc|kvzalloc";
> identifier VAR, ELEMENT;
> expression COUNT;
> @@
>
> - alloc(sizeof(*VAR) + COUNT * sizeof(*VAR->ELEMENT)
> + alloc(struct_size(VAR, ELEMENT, COUNT)
>   , ...)
>
> But I needed to explicitly change the rule to:
>
> (
> - alloc(sizeof(*VAR) + COUNT * sizeof(*VAR->ELEMENT)
> + alloc(struct_size(VAR, ELEMENT, COUNT)
>   , ...)
> |
> - alloc(sizeof(*VAR) + (COUNT * sizeof(*VAR->ELEMENT))
> + alloc(struct_size(VAR, ELEMENT, COUNT)
>   , ...)
> )
>
> to add the ()s. I would expect arithmetic commutative expressions to
> match? But I had to add parens?

Isomorphisms don't add parens.  They only remove them.  If they added
them, you would end up with the possibility of having them everywhere, in
all permutations, which would be slow and useless.

julia

[Cocci] [Fwd: Re: [PATCH] rtc: sun6i: Use struct_size() in kzalloc()]

[Kees Cook]

On Thu, Aug 23, 2018 at 3:00 PM, Julia Lawall <julia.lawall@lip6.fr> wrote:
>
>
> On Thu, 23 Aug 2018, Kees Cook wrote:
>
>> On Thu, Aug 23, 2018 at 2:48 PM, Joe Perches <joe@perches.com> wrote:
>> > Forwarding a question about coccinelle and isomorphisms from Kees Cook
>> >
>> > ---------- Forwarded message ----------
>> > From: Kees Cook <keescook@chromium.org>
>> > To: "Gustavo A. R. Silva" <gustavo@embeddedor.com>
>> > Cc: Alessandro Zummo <a.zummo@towertech.it>, Alexandre Belloni <alexandre.belloni@bootlin.com>, Maxime Ripard <maxime.ripard@bootlin.com>, Chen-Yu Tsai <wens@csie.org>, linux-rtc at vger.kernel.org, linux-arm-kernel <linux-arm-kernel@lists.infradead.org>, LKML <linux-kernel@vger.kernel.org>
>> > Bcc:
>> > Date: Thu, 23 Aug 2018 13:56:35 -0700
>> > Subject: Re: [PATCH] rtc: sun6i: Use struct_size() in kzalloc()
>> > 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?
>>
>> I had this:
>>
>> @@
>> identifier alloc =~
>> "kmalloc|kzalloc|kmalloc_node|kzalloc_node|vmalloc|vzalloc|kvmalloc|kvzalloc";
>> identifier VAR, ELEMENT;
>> expression COUNT;
>> @@
>>
>> - alloc(sizeof(*VAR) + COUNT * sizeof(*VAR->ELEMENT)
>> + alloc(struct_size(VAR, ELEMENT, COUNT)
>>   , ...)
>>
>> But I needed to explicitly change the rule to:
>>
>> (
>> - alloc(sizeof(*VAR) + COUNT * sizeof(*VAR->ELEMENT)
>> + alloc(struct_size(VAR, ELEMENT, COUNT)
>>   , ...)
>> |
>> - alloc(sizeof(*VAR) + (COUNT * sizeof(*VAR->ELEMENT))
>> + alloc(struct_size(VAR, ELEMENT, COUNT)
>>   , ...)
>> )
>>
>> to add the ()s. I would expect arithmetic commutative expressions to
>> match? But I had to add parens?
>
> Isomorphisms don't add parens.  They only remove them.  If they added
> them, you would end up with the possibility of having them everywhere, in
> all permutations, which would be slow and useless.

Would a rule for:

a + (b * c)

match:

a + b * c

?

-Kees

-- 
Kees Cook
Pixel Security

[Cocci] [Fwd: Re: [PATCH] rtc: sun6i: Use struct_size() in kzalloc()]

[Julia Lawall]

On Thu, 23 Aug 2018, Kees Cook wrote:

> On Thu, Aug 23, 2018 at 3:00 PM, Julia Lawall <julia.lawall@lip6.fr> wrote:
> >
> >
> > On Thu, 23 Aug 2018, Kees Cook wrote:
> >
> >> On Thu, Aug 23, 2018 at 2:48 PM, Joe Perches <joe@perches.com> wrote:
> >> > Forwarding a question about coccinelle and isomorphisms from Kees Cook
> >> >
> >> > ---------- Forwarded message ----------
> >> > From: Kees Cook <keescook@chromium.org>
> >> > To: "Gustavo A. R. Silva" <gustavo@embeddedor.com>
> >> > Cc: Alessandro Zummo <a.zummo@towertech.it>, Alexandre Belloni <alexandre.belloni@bootlin.com>, Maxime Ripard <maxime.ripard@bootlin.com>, Chen-Yu Tsai <wens@csie.org>, linux-rtc at vger.kernel.org, linux-arm-kernel <linux-arm-kernel@lists.infradead.org>, LKML <linux-kernel@vger.kernel.org>
> >> > Bcc:
> >> > Date: Thu, 23 Aug 2018 13:56:35 -0700
> >> > Subject: Re: [PATCH] rtc: sun6i: Use struct_size() in kzalloc()
> >> > 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?
> >>
> >> I had this:
> >>
> >> @@
> >> identifier alloc =~
> >> "kmalloc|kzalloc|kmalloc_node|kzalloc_node|vmalloc|vzalloc|kvmalloc|kvzalloc";
> >> identifier VAR, ELEMENT;
> >> expression COUNT;
> >> @@
> >>
> >> - alloc(sizeof(*VAR) + COUNT * sizeof(*VAR->ELEMENT)
> >> + alloc(struct_size(VAR, ELEMENT, COUNT)
> >>   , ...)
> >>
> >> But I needed to explicitly change the rule to:
> >>
> >> (
> >> - alloc(sizeof(*VAR) + COUNT * sizeof(*VAR->ELEMENT)
> >> + alloc(struct_size(VAR, ELEMENT, COUNT)
> >>   , ...)
> >> |
> >> - alloc(sizeof(*VAR) + (COUNT * sizeof(*VAR->ELEMENT))
> >> + alloc(struct_size(VAR, ELEMENT, COUNT)
> >>   , ...)
> >> )
> >>
> >> to add the ()s. I would expect arithmetic commutative expressions to
> >> match? But I had to add parens?
> >
> > Isomorphisms don't add parens.  They only remove them.  If they added
> > them, you would end up with the possibility of having them everywhere, in
> > all permutations, which would be slow and useless.
>
> Would a rule for:
>
> a + (b * c)
>
> match:
>
> a + b * c

I would say yes.  Basically it removes the parentheses but doesn't reparse
the code, so it doesn't redo the associativity.  Since * has higher
precedence than +, then both will be matched.  On the other hand, if you
put:

(a + b) * c

It will consider a pattern with the parentheses removed, but that pattern
won't match anything, because real trees that consist of a + b * c are
parsed in a different way.

julia

[Cocci] [Fwd: Re: [PATCH] rtc: sun6i: Use struct_size() in kzalloc()]

[Joe Perches]

On Thu, 2018-08-23 at 18:13 -0400, Julia Lawall wrote:
> 
> On Thu, 23 Aug 2018, Kees Cook wrote:
> 
> > On Thu, Aug 23, 2018 at 3:00 PM, Julia Lawall <julia.lawall@lip6.fr> wrote:
> > > 
> > > 
> > > On Thu, 23 Aug 2018, Kees Cook wrote:
> > > 
> > > > On Thu, Aug 23, 2018 at 2:48 PM, Joe Perches <joe@perches.com> wrote:
> > > > > Forwarding a question about coccinelle and isomorphisms from Kees Cook
> > > > > 
> > > > > ---------- Forwarded message ----------
> > > > > From: Kees Cook <keescook@chromium.org>
> > > > > To: "Gustavo A. R. Silva" <gustavo@embeddedor.com>
> > > > > Cc: Alessandro Zummo <a.zummo@towertech.it>, Alexandre Belloni <alexandre.belloni@bootlin.com>, Maxime Ripard <maxime.ripard@bootlin.com>, Chen-Yu Tsai <wens@csie.org>, linux-rtc at vger.kernel.org, linux-arm-kernel <linux-arm-kernel@lists.infradead.org>, LKML <linux-kernel@vger.kernel.org>
> > > > > Bcc:
> > > > > Date: Thu, 23 Aug 2018 13:56:35 -0700
> > > > > Subject: Re: [PATCH] rtc: sun6i: Use struct_size() in kzalloc()
> > > > > 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?
> > > > 
> > > > I had this:
> > > > 
> > > > @@
> > > > identifier alloc =~
> > > > "kmalloc|kzalloc|kmalloc_node|kzalloc_node|vmalloc|vzalloc|kvmalloc|kvzalloc";
> > > > identifier VAR, ELEMENT;
> > > > expression COUNT;
> > > > @@
> > > > 
> > > > - alloc(sizeof(*VAR) + COUNT * sizeof(*VAR->ELEMENT)
> > > > + alloc(struct_size(VAR, ELEMENT, COUNT)
> > > >   , ...)
> > > > 
> > > > But I needed to explicitly change the rule to:
> > > > 
> > > > (
> > > > - alloc(sizeof(*VAR) + COUNT * sizeof(*VAR->ELEMENT)
> > > > + alloc(struct_size(VAR, ELEMENT, COUNT)
> > > >   , ...)
> > > > > 
> > > > 
> > > > - alloc(sizeof(*VAR) + (COUNT * sizeof(*VAR->ELEMENT))
> > > > + alloc(struct_size(VAR, ELEMENT, COUNT)
> > > >   , ...)
> > > > )
> > > > 
> > > > to add the ()s. I would expect arithmetic commutative expressions to
> > > > match? But I had to add parens?
> > > 
> > > Isomorphisms don't add parens.  They only remove them.  If they added
> > > them, you would end up with the possibility of having them everywhere, in
> > > all permutations, which would be slow and useless.
> > 
> > Would a rule for:
> > 
> > a + (b * c)
> > 
> > match:
> > 
> > a + b * c
> 
> I would say yes.  Basically it removes the parentheses but doesn't reparse
> the code, so it doesn't redo the associativity.  Since * has higher
> precedence than +, then both will be matched.  On the other hand, if you
> put:
> 
> (a + b) * c
> 
> It will consider a pattern with the parentheses removed, but that pattern
> won't match anything, because real trees that consist of a + b * c are
> parsed in a different way.

spatch 1.0.4 doesn't seem to:

$ spatch --version
spatch version 1.0.4 with Python support and with PCRE support
$ cat match_mul.cocci 
@@
expression a, b, c;
int d;
@@

*	d = a * b + c;
$ cat test_mul.c 
int a, b, c, d;

void foo(void)
{
	d = (a * b) + c;
	d = a * b + c;
}
$ spatch -sp-file match_mul.cocci test_mul.c
init_defs_builtins: /usr/lib/coccinelle/standard.h
HANDLING: test_mul.c
diff = 
--- test_mul.c
+++ /tmp/cocci-output-22607-ba6f76-test_mul.c
@@ -3,5 +3,4 @@ int a, b, c, d;
 void foo(void)
 {
 	d = (a * b) + c;
-	d = a * b + c;
 }

[Cocci] [Fwd: Re: [PATCH] rtc: sun6i: Use struct_size() in kzalloc()]

[Kees Cook]

On Thu, Aug 23, 2018 at 3:21 PM, Joe Perches <joe@perches.com> wrote:
> On Thu, 2018-08-23 at 18:13 -0400, Julia Lawall wrote:
>>
>> On Thu, 23 Aug 2018, Kees Cook wrote:
>>
>> (a + b) * c
>>
>> It will consider a pattern with the parentheses removed, but that pattern
>> won't match anything, because real trees that consist of a + b * c are
>> parsed in a different way.
>
> spatch 1.0.4 doesn't seem to:
>
> $ spatch --version
> spatch version 1.0.4 with Python support and with PCRE support
> $ cat match_mul.cocci
> @@
> expression a, b, c;
> int d;
> @@
>
> *       d = a * b + c;

But "(a * b) + c" for the rule does:


$ cat isomorphisms.c
#include <stdio.h>
#include <stdlib.h>

int main(int argc, char *argv[])
{
        int a, b, c;

        a = atoi(argv[1]);
        b = atoi(argv[2]);
        c = atoi(argv[3]);

        printf("%d\n", a + b * c);
        printf("%d\n", (a + b) * c);
        printf("%d\n", a + (b * c));
        printf("%d\n", b * c + a);
        printf("%d\n", b * (c + a));
        printf("%d\n", (b * c) + a);

        return 0;
}
$ cat match.cocci
@@
identifier A, B, C;
@@

* (A * B) + C

$ spatch -sp-file match.cocci isomorphisms.c
init_defs_builtins: /usr/lib/coccinelle/standard.h
HANDLING: isomorphisms.c
diff =
--- isomorphisms.c
+++ /tmp/cocci-output-8402-870fd6-isomorphisms.c
@@ -9,12 +9,8 @@ int main(int argc, char *argv[])
        b = atoi(argv[2]);
        c = atoi(argv[3]);

-       printf("%d\n", a + b * c);
        printf("%d\n", (a + b) * c);
-       printf("%d\n", a + (b * c));
-       printf("%d\n", b * c + a);
        printf("%d\n", b * (c + a));
-       printf("%d\n", (b * c) + a);

        return 0;
 }


So it sounds like I should put parens around all kinds of things in my rules...

-Kees

-- 
Kees Cook
Pixel Security

[Cocci] [Fwd: Re: [PATCH] rtc: sun6i: Use struct_size() in kzalloc()]

[Julia Lawall]

On Thu, 23 Aug 2018, Kees Cook wrote:

> On Thu, Aug 23, 2018 at 3:21 PM, Joe Perches <joe@perches.com> wrote:
> > On Thu, 2018-08-23 at 18:13 -0400, Julia Lawall wrote:
> >>
> >> On Thu, 23 Aug 2018, Kees Cook wrote:
> >>
> >> (a + b) * c
> >>
> >> It will consider a pattern with the parentheses removed, but that pattern
> >> won't match anything, because real trees that consist of a + b * c are
> >> parsed in a different way.
> >
> > spatch 1.0.4 doesn't seem to:
> >
> > $ spatch --version
> > spatch version 1.0.4 with Python support and with PCRE support
> > $ cat match_mul.cocci
> > @@
> > expression a, b, c;
> > int d;
> > @@
> >
> > *       d = a * b + c;
>
> But "(a * b) + c" for the rule does:
>
>
> $ cat isomorphisms.c
> #include <stdio.h>
> #include <stdlib.h>
>
> int main(int argc, char *argv[])
> {
>         int a, b, c;
>
>         a = atoi(argv[1]);
>         b = atoi(argv[2]);
>         c = atoi(argv[3]);
>
>         printf("%d\n", a + b * c);
>         printf("%d\n", (a + b) * c);
>         printf("%d\n", a + (b * c));
>         printf("%d\n", b * c + a);
>         printf("%d\n", b * (c + a));
>         printf("%d\n", (b * c) + a);
>
>         return 0;
> }
> $ cat match.cocci
> @@
> identifier A, B, C;
> @@
>
> * (A * B) + C
>
> $ spatch -sp-file match.cocci isomorphisms.c
> init_defs_builtins: /usr/lib/coccinelle/standard.h
> HANDLING: isomorphisms.c
> diff =
> --- isomorphisms.c
> +++ /tmp/cocci-output-8402-870fd6-isomorphisms.c
> @@ -9,12 +9,8 @@ int main(int argc, char *argv[])
>         b = atoi(argv[2]);
>         c = atoi(argv[3]);
>
> -       printf("%d\n", a + b * c);
>         printf("%d\n", (a + b) * c);
> -       printf("%d\n", a + (b * c));
> -       printf("%d\n", b * c + a);
>         printf("%d\n", b * (c + a));
> -       printf("%d\n", (b * c) + a);
>
>         return 0;
>  }
>
>
> So it sounds like I should put parens around all kinds of things in my rules...

If you think someone might reasonably use parentheses somewhere, you
should put them.

julia

[Cocci] [Fwd: Re: [PATCH] rtc: sun6i: Use struct_size() in kzalloc()]

[Joe Perches]

On Thu, 2018-08-23 at 15:27 -0700, Kees Cook wrote:
> On Thu, Aug 23, 2018 at 3:21 PM, Joe Perches <joe@perches.com> wrote:
> > On Thu, 2018-08-23 at 18:13 -0400, Julia Lawall wrote:
> > > 
> > > On Thu, 23 Aug 2018, Kees Cook wrote:
> > > 
> > > (a + b) * c
> > > 
> > > It will consider a pattern with the parentheses removed, but that pattern
> > > won't match anything, because real trees that consist of a + b * c are
> > > parsed in a different way.
> > 
> > spatch 1.0.4 doesn't seem to:
> > 
> > $ spatch --version
> > spatch version 1.0.4 with Python support and with PCRE support
> > $ cat match_mul.cocci
> > @@
> > expression a, b, c;
> > int d;
> > @@
> > 
> > *       d = a * b + c;
> 
> But "(a * b) + c" for the rule does:

Yes, but not for other valid uses like below:

$ cat match_mul.cocci
@@
expression a, b, c;
int d;
@@

*	d = (a * b) + c;
$ cat test_mul.c 
int a, b, c, d;

void foo(void)
{
	d = ((a * b) + c);
	d = ((a * b)) + c;
	d = (a * b) + c;
	d = a * b + c;
}
$ spatch -sp-file match_mul.cocci test_mul.c
init_defs_builtins: /usr/lib/coccinelle/standard.h
HANDLING: test_mul.c
diff = 
--- test_mul.c
+++ /tmp/cocci-output-23856-7e83f7-test_mul.c
@@ -4,6 +4,4 @@ void foo(void)
 {
 	d = ((a * b) + c);
 	d = ((a * b)) + c;
-	d = (a * b) + c;
-	d = a * b + c;
 }

[Cocci] [Fwd: Re: [PATCH] rtc: sun6i: Use struct_size() in kzalloc()]

[Julia Lawall]

On Thu, 23 Aug 2018, Joe Perches wrote:

> On Thu, 2018-08-23 at 15:27 -0700, Kees Cook wrote:
> > On Thu, Aug 23, 2018 at 3:21 PM, Joe Perches <joe@perches.com> wrote:
> > > On Thu, 2018-08-23 at 18:13 -0400, Julia Lawall wrote:
> > > >
> > > > On Thu, 23 Aug 2018, Kees Cook wrote:
> > > >
> > > > (a + b) * c
> > > >
> > > > It will consider a pattern with the parentheses removed, but that pattern
> > > > won't match anything, because real trees that consist of a + b * c are
> > > > parsed in a different way.
> > >
> > > spatch 1.0.4 doesn't seem to:
> > >
> > > $ spatch --version
> > > spatch version 1.0.4 with Python support and with PCRE support
> > > $ cat match_mul.cocci
> > > @@
> > > expression a, b, c;
> > > int d;
> > > @@
> > >
> > > *       d = a * b + c;
> >
> > But "(a * b) + c" for the rule does:
>
> Yes, but not for other valid uses like below:
>
> $ cat match_mul.cocci
> @@
> expression a, b, c;
> int d;
> @@
>
> *	d = (a * b) + c;
> $ cat test_mul.c
> int a, b, c, d;
>
> void foo(void)
> {
> 	d = ((a * b) + c);
> 	d = ((a * b)) + c;
> 	d = (a * b) + c;
> 	d = a * b + c;
> }
> $ spatch -sp-file match_mul.cocci test_mul.c
> init_defs_builtins: /usr/lib/coccinelle/standard.h
> HANDLING: test_mul.c
> diff =
> --- test_mul.c
> +++ /tmp/cocci-output-23856-7e83f7-test_mul.c
> @@ -4,6 +4,4 @@ void foo(void)
>  {
>  	d = ((a * b) + c);
>  	d = ((a * b)) + c;
> -	d = (a * b) + c;
> -	d = a * b + c;
>  }

I'm not sure to get the point.

If you think that people may fully parenthesize the code, then ((a * b) +
c) would be a reasonable option for the pattern.  I'm not sure why double
parentheses, ((a * b)) + c, should exist in the first place.

julia

[Cocci] [Fwd: Re: [PATCH] rtc: sun6i: Use struct_size() in kzalloc()]

[Joe Perches]

On Thu, 2018-08-23 at 20:17 -0400, Julia Lawall wrote:
> 
> On Thu, 23 Aug 2018, Joe Perches wrote:
> 
> > On Thu, 2018-08-23 at 15:27 -0700, Kees Cook wrote:
> > > On Thu, Aug 23, 2018 at 3:21 PM, Joe Perches <joe@perches.com> wrote:
> > > > On Thu, 2018-08-23 at 18:13 -0400, Julia Lawall wrote:
> > > > > 
> > > > > On Thu, 23 Aug 2018, Kees Cook wrote:
> > > > > 
> > > > > (a + b) * c
> > > > > 
> > > > > It will consider a pattern with the parentheses removed, but that pattern
> > > > > won't match anything, because real trees that consist of a + b * c are
> > > > > parsed in a different way.
> > > > 
> > > > spatch 1.0.4 doesn't seem to:
> > > > 
> > > > $ spatch --version
> > > > spatch version 1.0.4 with Python support and with PCRE support
> > > > $ cat match_mul.cocci
> > > > @@
> > > > expression a, b, c;
> > > > int d;
> > > > @@
> > > > 
> > > > *       d = a * b + c;
> > > 
> > > But "(a * b) + c" for the rule does:
> > 
> > Yes, but not for other valid uses like below:
> > 
> > $ cat match_mul.cocci
> > @@
> > expression a, b, c;
> > int d;
> > @@
> > 
> > *	d = (a * b) + c;
> > $ cat test_mul.c
> > int a, b, c, d;
> > 
> > void foo(void)
> > {
> > 	d = ((a * b) + c);
> > 	d = ((a * b)) + c;
> > 	d = (a * b) + c;
> > 	d = a * b + c;
> > }
> > $ spatch -sp-file match_mul.cocci test_mul.c
> > init_defs_builtins: /usr/lib/coccinelle/standard.h
> > HANDLING: test_mul.c
> > diff =
> > --- test_mul.c
> > +++ /tmp/cocci-output-23856-7e83f7-test_mul.c
> > @@ -4,6 +4,4 @@ void foo(void)
> >  {
> >  	d = ((a * b) + c);
> >  	d = ((a * b)) + c;
> > -	d = (a * b) + c;
> > -	d = a * b + c;
> >  }
> 
> I'm not sure to get the point.
> 
> If you think that people may fully parenthesize the code, then ((a * b) +
> c) would be a reasonable option for the pattern.  I'm not sure why double
> parentheses, ((a * b)) + c, should exist in the first place.

People who write code do a lot of unnecessary things.
It's code I've seen in the past.
It occurs more with expressions than identifiers.

It'd be nice if coccinelle could parse arbitrarily
parenthesized code and script down to its minimal
logical requirements and match as maximally as possible.

cheers, Joe

Re: [PATCH] rtc: sun6i: Use struct_size() in kzalloc()

[Gustavo A. R. Silva]

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

[PATCH] rtc: sun6i: Use struct_size() in kzalloc()

[Gustavo A. R. Silva]

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

Re: [PATCH] rtc: sun6i: Use struct_size() in kzalloc()

[Kees Cook]

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

[PATCH] rtc: sun6i: Use struct_size() in kzalloc()

[Kees Cook]

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

Re: [PATCH] rtc: sun6i: Use struct_size() in kzalloc()

[Alexandre Belloni]

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

[PATCH] rtc: sun6i: Use struct_size() in kzalloc()

[Alexandre Belloni]

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