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* [PATCH] mm: fix protection of mm_struct fields in get_cmdline()
@ 2019-05-15  8:15 Konstantin Khlebnikov
  2019-05-15  8:22 ` Oscar Salvador
  2019-05-15  8:38 ` Kirill Tkhai
  0 siblings, 2 replies; 4+ messages in thread
From: Konstantin Khlebnikov @ 2019-05-15  8:15 UTC (permalink / raw)
  To: linux-mm, Andrew Morton, linux-kernel; +Cc: Michal Hocko, Yang Shi

Since commit 88aa7cc688d4 ("mm: introduce arg_lock to protect arg_start|
end and env_start|end in mm_struct") related mm fields are protected with
separate spinlock and mmap_sem held for read is not enough for protection.

Fixes: 88aa7cc688d4 ("mm: introduce arg_lock to protect arg_start|end and env_start|end in mm_struct")
Signed-off-by: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
---
 mm/util.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/mm/util.c b/mm/util.c
index e2e4f8c3fa12..540e7c157cf2 100644
--- a/mm/util.c
+++ b/mm/util.c
@@ -717,12 +717,12 @@ int get_cmdline(struct task_struct *task, char *buffer, int buflen)
 	if (!mm->arg_end)
 		goto out_mm;	/* Shh! No looking before we're done */
 
-	down_read(&mm->mmap_sem);
+	spin_lock(&mm->arg_lock);
 	arg_start = mm->arg_start;
 	arg_end = mm->arg_end;
 	env_start = mm->env_start;
 	env_end = mm->env_end;
-	up_read(&mm->mmap_sem);
+	spin_unlock(&mm->arg_lock);
 
 	len = arg_end - arg_start;
 


^ permalink raw reply related	[flat|nested] 4+ messages in thread
* Re: [PATCH] mm: fix protection of mm_struct fields in get_cmdline()
  2019-05-15  8:15 [PATCH] mm: fix protection of mm_struct fields in get_cmdline() Konstantin Khlebnikov
@ 2019-05-15  8:22 ` Oscar Salvador
  2019-05-15  8:36   ` Konstantin Khlebnikov
  2019-05-15  8:38 ` Kirill Tkhai
  1 sibling, 1 reply; 4+ messages in thread
From: Oscar Salvador @ 2019-05-15  8:22 UTC (permalink / raw)
  To: Konstantin Khlebnikov
  Cc: linux-mm, Andrew Morton, linux-kernel, Michal Hocko, Yang Shi, mkoutny

On Wed, May 15, 2019 at 11:15:37AM +0300, Konstantin Khlebnikov wrote:
> Since commit 88aa7cc688d4 ("mm: introduce arg_lock to protect arg_start|
> end and env_start|end in mm_struct") related mm fields are protected with
> separate spinlock and mmap_sem held for read is not enough for protection.
> 
> Fixes: 88aa7cc688d4 ("mm: introduce arg_lock to protect arg_start|end and env_start|end in mm_struct")
> Signed-off-by: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>

This was already addressed by [1]?

[1] https://patchwork.kernel.org/patch/10923003/

> ---
>  mm/util.c |    4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/mm/util.c b/mm/util.c
> index e2e4f8c3fa12..540e7c157cf2 100644
> --- a/mm/util.c
> +++ b/mm/util.c
> @@ -717,12 +717,12 @@ int get_cmdline(struct task_struct *task, char *buffer, int buflen)
>  	if (!mm->arg_end)
>  		goto out_mm;	/* Shh! No looking before we're done */
>  
> -	down_read(&mm->mmap_sem);
> +	spin_lock(&mm->arg_lock);
>  	arg_start = mm->arg_start;
>  	arg_end = mm->arg_end;
>  	env_start = mm->env_start;
>  	env_end = mm->env_end;
> -	up_read(&mm->mmap_sem);
> +	spin_unlock(&mm->arg_lock);
>  
>  	len = arg_end - arg_start;
>  
> 

-- 
Oscar Salvador
SUSE L3

^ permalink raw reply	[flat|nested] 4+ messages in thread
* Re: [PATCH] mm: fix protection of mm_struct fields in get_cmdline()
  2019-05-15  8:22 ` Oscar Salvador
@ 2019-05-15  8:36   ` Konstantin Khlebnikov
  0 siblings, 0 replies; 4+ messages in thread
From: Konstantin Khlebnikov @ 2019-05-15  8:36 UTC (permalink / raw)
  To: Oscar Salvador
  Cc: linux-mm, Andrew Morton, linux-kernel, Michal Hocko, Yang Shi, mkoutny



On 15.05.2019 11:22, Oscar Salvador wrote:
> On Wed, May 15, 2019 at 11:15:37AM +0300, Konstantin Khlebnikov wrote:
>> Since commit 88aa7cc688d4 ("mm: introduce arg_lock to protect arg_start|
>> end and env_start|end in mm_struct") related mm fields are protected with
>> separate spinlock and mmap_sem held for read is not enough for protection.
>>
>> Fixes: 88aa7cc688d4 ("mm: introduce arg_lock to protect arg_start|end and env_start|end in mm_struct")
>> Signed-off-by: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
> 
> This was already addressed by [1]?

Yep.

> 
> [1] https://patchwork.kernel.org/patch/10923003/
> 
>> ---
>>   mm/util.c |    4 ++--
>>   1 file changed, 2 insertions(+), 2 deletions(-)
>>
>> diff --git a/mm/util.c b/mm/util.c
>> index e2e4f8c3fa12..540e7c157cf2 100644
>> --- a/mm/util.c
>> +++ b/mm/util.c
>> @@ -717,12 +717,12 @@ int get_cmdline(struct task_struct *task, char *buffer, int buflen)
>>   	if (!mm->arg_end)
>>   		goto out_mm;	/* Shh! No looking before we're done */
>>   
>> -	down_read(&mm->mmap_sem);
>> +	spin_lock(&mm->arg_lock);
>>   	arg_start = mm->arg_start;
>>   	arg_end = mm->arg_end;
>>   	env_start = mm->env_start;
>>   	env_end = mm->env_end;
>> -	up_read(&mm->mmap_sem);
>> +	spin_unlock(&mm->arg_lock);
>>   
>>   	len = arg_end - arg_start;
>>   
>>
> 

^ permalink raw reply	[flat|nested] 4+ messages in thread
* Re: [PATCH] mm: fix protection of mm_struct fields in get_cmdline()
  2019-05-15  8:15 [PATCH] mm: fix protection of mm_struct fields in get_cmdline() Konstantin Khlebnikov
  2019-05-15  8:22 ` Oscar Salvador
@ 2019-05-15  8:38 ` Kirill Tkhai
  1 sibling, 0 replies; 4+ messages in thread
From: Kirill Tkhai @ 2019-05-15  8:38 UTC (permalink / raw)
  To: Konstantin Khlebnikov, linux-mm, mkoutny, Andrew Morton, linux-kernel
  Cc: Michal Hocko, Yang Shi

Hi, Konstantin,

On 15.05.2019 11:15, Konstantin Khlebnikov wrote:
> Since commit 88aa7cc688d4 ("mm: introduce arg_lock to protect arg_start|
> end and env_start|end in mm_struct") related mm fields are protected with
> separate spinlock and mmap_sem held for read is not enough for protection.
> 
> Fixes: 88aa7cc688d4 ("mm: introduce arg_lock to protect arg_start|end and env_start|end in mm_struct")
> Signed-off-by: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>

is this already fixed in Michal's series: https://lkml.org/lkml/2019/5/2/422 ?

Thanks,
Kirill

> ---
>  mm/util.c |    4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/mm/util.c b/mm/util.c
> index e2e4f8c3fa12..540e7c157cf2 100644
> --- a/mm/util.c
> +++ b/mm/util.c
> @@ -717,12 +717,12 @@ int get_cmdline(struct task_struct *task, char *buffer, int buflen)
>  	if (!mm->arg_end)
>  		goto out_mm;	/* Shh! No looking before we're done */
>  
> -	down_read(&mm->mmap_sem);
> +	spin_lock(&mm->arg_lock);
>  	arg_start = mm->arg_start;
>  	arg_end = mm->arg_end;
>  	env_start = mm->env_start;
>  	env_end = mm->env_end;
> -	up_read(&mm->mmap_sem);
> +	spin_unlock(&mm->arg_lock);
>  
>  	len = arg_end - arg_start;
>  
> 


^ permalink raw reply	[flat|nested] 4+ messages in thread
end of thread, other threads:[~2019-05-15  8:38 UTC | newest]

Thread overview: 4+ messages (download: mbox.gz / follow: Atom feed)
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2019-05-15  8:15 [PATCH] mm: fix protection of mm_struct fields in get_cmdline() Konstantin Khlebnikov
2019-05-15  8:22 ` Oscar Salvador
2019-05-15  8:36   ` Konstantin Khlebnikov
2019-05-15  8:38 ` Kirill Tkhai

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