[PATCH 8/9] arch/powerpc/sysdev/ehv_pic.c: add missing kfree

[PATCH 8/9] arch/powerpc/sysdev/ehv_pic.c: add missing kfree

[Julia Lawall]

From: Julia Lawall <julia@diku.dk>

At this point, ehv_pic has been allocated but not stored anywhere, so it
should be freed before leaving the function.

A simplified version of the semantic match that finds this problem is as
follows: (http://coccinelle.lip6.fr/)

// <smpl>
@exists@
local idexpression x;
statement S,S1;
expression E;
identifier fl;
expression *ptr != NULL;
@@

x = \(kmalloc\|kzalloc\|kcalloc\)(...);
...
if (x == NULL) S
<... when != x
     when != if (...) { <+...kfree(x)...+> }
     when any
     when != true x == NULL
x->fl
...>
(
if (x == NULL) S1
|
if (...) { ... when != x
               when forall
(
 return \(0\|<+...x...+>\|ptr\);
|
* return ...;
)
}
)
// </smpl>

Signed-off-by: Julia Lawall <julia@diku.dk>

---
 arch/powerpc/sysdev/ehv_pic.c |    1 +
 1 file changed, 1 insertion(+)

diff --git a/arch/powerpc/sysdev/ehv_pic.c b/arch/powerpc/sysdev/ehv_pic.c
index af1a5df..b6731e4 100644
--- a/arch/powerpc/sysdev/ehv_pic.c
+++ b/arch/powerpc/sysdev/ehv_pic.c
@@ -280,6 +280,7 @@ void __init ehv_pic_init(void)
 
 	if (!ehv_pic->irqhost) {
 		of_node_put(np);
+		kfree(ehv_pic);
 		return;
 	}
 

Re: [PATCH 8/9] arch/powerpc/sysdev/ehv_pic.c: add missing kfree

[Tabi Timur-B04825]

On Mon, Aug 8, 2011 at 7:18 AM, Julia Lawall <julia@diku.dk> wrote:

> diff --git a/arch/powerpc/sysdev/ehv_pic.c b/arch/powerpc/sysdev/ehv_pic.c
> index af1a5df..b6731e4 100644
> --- a/arch/powerpc/sysdev/ehv_pic.c
> +++ b/arch/powerpc/sysdev/ehv_pic.c
> @@ -280,6 +280,7 @@ void __init ehv_pic_init(void)
>
>        if (!ehv_pic->irqhost) {
>                of_node_put(np);
> +               kfree(ehv_pic);
>                return;
>        }

Although the fix is correct, I think there is another bug in this
function.  'np' is not released when the function finishes
successfully.   I've looked at other functions that use
irq_alloc_host(), and most of them do the same thing: they don't call
of_node_put() on the device node pointer.  The only exception I've
found is mpc5121_ads_cpld_pic_init().

Ben, Kumar: am I missing something?  irq_alloc_host() calls of_node_get():

	host->of_node = of_node_get(of_node);

so doesn't that mean that the caller of irq_alloc_host() should
release the device node pointer?

-- 
Timur Tabi
Linux kernel developer at Freescale

Re: [PATCH 8/9] arch/powerpc/sysdev/ehv_pic.c: add missing kfree

[Timur Tabi]

Julia Lawall wrote:
> At this point, ehv_pic has been allocated but not stored anywhere, so it
> should be freed before leaving the function.

Acked-by: Timur Tabi <timur@freescale.com>

FYI, Ashish is no longer with Freescale, so I've taken over maintainership of
ehv_pic.

-- 
Timur Tabi
Linux kernel developer at Freescale

Re: [PATCH 8/9] arch/powerpc/sysdev/ehv_pic.c: add missing kfree

[Timur Tabi]

Ben, Kumar, can one of you take a look at my question and help me out?

 wrote:
> On Mon, Aug 8, 2011 at 7:18 AM, Julia Lawall <julia@diku.dk> wrote:
> 
>> diff --git a/arch/powerpc/sysdev/ehv_pic.c b/arch/powerpc/sysdev/ehv_pic.c
>> index af1a5df..b6731e4 100644
>> --- a/arch/powerpc/sysdev/ehv_pic.c
>> +++ b/arch/powerpc/sysdev/ehv_pic.c
>> @@ -280,6 +280,7 @@ void __init ehv_pic_init(void)
>>
>>        if (!ehv_pic->irqhost) {
>>                of_node_put(np);
>> +               kfree(ehv_pic);
>>                return;
>>        }
> 
> Although the fix is correct, I think there is another bug in this
> function.  'np' is not released when the function finishes
> successfully.   I've looked at other functions that use
> irq_alloc_host(), and most of them do the same thing: they don't call
> of_node_put() on the device node pointer.  The only exception I've
> found is mpc5121_ads_cpld_pic_init().
> 
> Ben, Kumar: am I missing something?  irq_alloc_host() calls of_node_get():
> 
> 	host->of_node = of_node_get(of_node);
> 
> so doesn't that mean that the caller of irq_alloc_host() should
> release the device node pointer?
> 


-- 
Timur Tabi
Linux kernel developer at Freescale

Re: [PATCH 8/9] arch/powerpc/sysdev/ehv_pic.c: add missing kfree

[Kumar Gala]

On Aug 8, 2011, at 6:18 AM, Julia Lawall wrote:

> From: Julia Lawall <julia@diku.dk>
> 
> At this point, ehv_pic has been allocated but not stored anywhere, so it
> should be freed before leaving the function.
> 
> A simplified version of the semantic match that finds this problem is as
> follows: (http://coccinelle.lip6.fr/)
> 
> // <smpl>
> @exists@
> local idexpression x;
> statement S,S1;
> expression E;
> identifier fl;
> expression *ptr != NULL;
> @@
> 
> x = \(kmalloc\|kzalloc\|kcalloc\)(...);
> ...
> if (x == NULL) S
> <... when != x
>     when != if (...) { <+...kfree(x)...+> }
>     when any
>     when != true x == NULL
> x->fl
> ...>
> (
> if (x == NULL) S1
> |
> if (...) { ... when != x
>               when forall
> (
> return \(0\|<+...x...+>\|ptr\);
> |
> * return ...;
> )
> }
> )
> // </smpl>
> 
> Signed-off-by: Julia Lawall <julia@diku.dk>
> 
> ---
> arch/powerpc/sysdev/ehv_pic.c |    1 +
> 1 file changed, 1 insertion(+)

applied to next

- k