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* [PATCH] Fix potentially derefencing uninitialized 'r'.
@ 2012-02-03  8:20 Geunsik Lim
  2012-02-17 22:28 ` Andrew Morton
  0 siblings, 1 reply; 3+ messages in thread
From: Geunsik Lim @ 2012-02-03  8:20 UTC (permalink / raw)
  To: Andrew Morton, H. Peter Anvin; +Cc: Yinghai Lu, linux-kernel, linux-mm

struct memblock_region 'r' will not be initialized potentially
because of while statement's condition in __next_mem_pfn_range()function.
Initialize struct memblock_region data structure by default.

Signed-off-by: Geunsik Lim <geunsik.lim@samsung.com>
---
 mm/memblock.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/mm/memblock.c b/mm/memblock.c
index 77b5f22..867f5a2 100644
--- a/mm/memblock.c
+++ b/mm/memblock.c
@@ -671,7 +671,7 @@ void __init_memblock __next_mem_pfn_range(int *idx, int nid,
 				unsigned long *out_end_pfn, int *out_nid)
 {
 	struct memblock_type *type = &memblock.memory;
-	struct memblock_region *r;
+	struct memblock_region *r = &type->regions[*idx];
 
 	while (++*idx < type->cnt) {
 		r = &type->regions[*idx];
-- 
1.7.8.1

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^ permalink raw reply related	[flat|nested] 3+ messages in thread

* Re: [PATCH] Fix potentially derefencing uninitialized 'r'.
  2012-02-03  8:20 [PATCH] Fix potentially derefencing uninitialized 'r' Geunsik Lim
@ 2012-02-17 22:28 ` Andrew Morton
  2012-02-20  7:57   ` Geunsik Lim
  0 siblings, 1 reply; 3+ messages in thread
From: Andrew Morton @ 2012-02-17 22:28 UTC (permalink / raw)
  To: Geunsik Lim; +Cc: H. Peter Anvin, Yinghai Lu, linux-kernel, linux-mm

On Fri,  3 Feb 2012 17:20:56 +0900
Geunsik Lim <geunsik.lim@gmail.com> wrote:

> struct memblock_region 'r' will not be initialized potentially
> because of while statement's condition in __next_mem_pfn_range()function.
> Initialize struct memblock_region data structure by default.
> 
> Signed-off-by: Geunsik Lim <geunsik.lim@samsung.com>
> ---
>  mm/memblock.c |    2 +-
>  1 files changed, 1 insertions(+), 1 deletions(-)
> 
> diff --git a/mm/memblock.c b/mm/memblock.c
> index 77b5f22..867f5a2 100644
> --- a/mm/memblock.c
> +++ b/mm/memblock.c
> @@ -671,7 +671,7 @@ void __init_memblock __next_mem_pfn_range(int *idx, int nid,
>  				unsigned long *out_end_pfn, int *out_nid)
>  {
>  	struct memblock_type *type = &memblock.memory;
> -	struct memblock_region *r;
> +	struct memblock_region *r = &type->regions[*idx];
>  
>  	while (++*idx < type->cnt) {
>  		r = &type->regions[*idx];

The following `if' test prevents any such dereference.

Maybe you saw a compilation warning (I didn't).  If so,
unintialized_var() is one way of suppressing it.

A better way is to reorganise the code (nicely).  Often that option
isn't available.


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^ permalink raw reply	[flat|nested] 3+ messages in thread

* Re: [PATCH] Fix potentially derefencing uninitialized 'r'.
  2012-02-17 22:28 ` Andrew Morton
@ 2012-02-20  7:57   ` Geunsik Lim
  0 siblings, 0 replies; 3+ messages in thread
From: Geunsik Lim @ 2012-02-20  7:57 UTC (permalink / raw)
  To: Andrew Morton; +Cc: H. Peter Anvin, Yinghai Lu, linux-kernel, linux-mm

On Sat, Feb 18, 2012 at 7:28 AM, Andrew Morton
<akpm@linux-foundation.org> wrote:
> On Fri,  3 Feb 2012 17:20:56 +0900
> Geunsik Lim <geunsik.lim@gmail.com> wrote:
>
>> struct memblock_region 'r' will not be initialized potentially
>> because of while statement's condition in __next_mem_pfn_range()function.
>> Initialize struct memblock_region data structure by default.
>>
>> Signed-off-by: Geunsik Lim <geunsik.lim@samsung.com>
>> ---
>>  mm/memblock.c |    2 +-
>>  1 files changed, 1 insertions(+), 1 deletions(-)
>>
>> diff --git a/mm/memblock.c b/mm/memblock.c
>> index 77b5f22..867f5a2 100644
>> --- a/mm/memblock.c
>> +++ b/mm/memblock.c
>> @@ -671,7 +671,7 @@ void __init_memblock __next_mem_pfn_range(int *idx, int nid,
>>                               unsigned long *out_end_pfn, int *out_nid)
>>  {
>>       struct memblock_type *type = &memblock.memory;
>> -     struct memblock_region *r;
>> +     struct memblock_region *r = &type->regions[*idx];
>>
>>       while (++*idx < type->cnt) {
>>               r = &type->regions[*idx];
>
> The following `if' test prevents any such dereference.
>
> Maybe you saw a compilation warning (I didn't).  If so,
> unintialized_var() is one way of suppressing it.
Yepp. This patch is  for solving compilation warning as you commented.
>
> A better way is to reorganise the code (nicely).  Often that option
> isn't available.
I will post patch again after reorganizing the code with better way.
Thanks.
>
>



-- 
----
Best regards,
Geunsik Lim, Samsung Electronics
http://leemgs.fedorapeople.org
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^ permalink raw reply	[flat|nested] 3+ messages in thread

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2012-02-03  8:20 [PATCH] Fix potentially derefencing uninitialized 'r' Geunsik Lim
2012-02-17 22:28 ` Andrew Morton
2012-02-20  7:57   ` Geunsik Lim

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