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* [PATCH] vfs: Fix possible chmod/truncate race condition.
@ 2008-10-15 19:35 Dmitri Monakhov
  2008-10-27  3:37 ` Andrew Morton
  0 siblings, 1 reply; 3+ messages in thread
From: Dmitri Monakhov @ 2008-10-15 19:35 UTC (permalink / raw)
  To: linux-kernel


Signed-off-by: Dmitri Monakhov <dmonakhov@openvz.org>
---
 fs/open.c |    3 +--
 1 files changed, 1 insertions(+), 2 deletions(-)

diff --git a/fs/open.c b/fs/open.c
index 07da935..3423b94 100644
--- a/fs/open.c
+++ b/fs/open.c
@@ -214,10 +214,9 @@ int do_truncate(struct dentry *dentry, loff_t length, unsigned int time_attrs,
 		newattrs.ia_valid |= ATTR_FILE;
 	}
 
+	mutex_lock(&dentry->d_inode->i_mutex);
 	/* Remove suid/sgid on truncate too */
 	newattrs.ia_valid |= should_remove_suid(dentry);
-
-	mutex_lock(&dentry->d_inode->i_mutex);
 	err = notify_change(dentry, &newattrs);
 	mutex_unlock(&dentry->d_inode->i_mutex);
 	return err;
-- 
1.5.4.3


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

* Re: [PATCH] vfs: Fix possible chmod/truncate race condition.
  2008-10-15 19:35 [PATCH] vfs: Fix possible chmod/truncate race condition Dmitri Monakhov
@ 2008-10-27  3:37 ` Andrew Morton
  2008-10-27  7:57   ` Dmitri Monakhov
  0 siblings, 1 reply; 3+ messages in thread
From: Andrew Morton @ 2008-10-27  3:37 UTC (permalink / raw)
  To: Dmitri Monakhov; +Cc: linux-kernel

On Wed, 15 Oct 2008 23:35:27 +0400 Dmitri Monakhov <dmonakhov@openvz.org> wrote:

> 
> Signed-off-by: Dmitri Monakhov <dmonakhov@openvz.org>
> ---
>  fs/open.c |    3 +--
>  1 files changed, 1 insertions(+), 2 deletions(-)
> 
> diff --git a/fs/open.c b/fs/open.c
> index 07da935..3423b94 100644
> --- a/fs/open.c
> +++ b/fs/open.c
> @@ -214,10 +214,9 @@ int do_truncate(struct dentry *dentry, loff_t length, unsigned int time_attrs,
>  		newattrs.ia_valid |= ATTR_FILE;
>  	}
>  
> +	mutex_lock(&dentry->d_inode->i_mutex);
>  	/* Remove suid/sgid on truncate too */
>  	newattrs.ia_valid |= should_remove_suid(dentry);
> -
> -	mutex_lock(&dentry->d_inode->i_mutex);
>  	err = notify_change(dentry, &newattrs);
>  	mutex_unlock(&dentry->d_inode->i_mutex);
>  	return err;

OK, I give up.  What race?

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

* Re: [PATCH] vfs: Fix possible chmod/truncate race condition.
  2008-10-27  3:37 ` Andrew Morton
@ 2008-10-27  7:57   ` Dmitri Monakhov
  0 siblings, 0 replies; 3+ messages in thread
From: Dmitri Monakhov @ 2008-10-27  7:57 UTC (permalink / raw)
  To: Andrew Morton; +Cc: linux-kernel

Andrew Morton <akpm@linux-foundation.org> writes:

> On Wed, 15 Oct 2008 23:35:27 +0400 Dmitri Monakhov <dmonakhov@openvz.org> wrote:
>
>> 
>> Signed-off-by: Dmitri Monakhov <dmonakhov@openvz.org>
>> ---
>>  fs/open.c |    3 +--
>>  1 files changed, 1 insertions(+), 2 deletions(-)
>> 
>> diff --git a/fs/open.c b/fs/open.c
>> index 07da935..3423b94 100644
>> --- a/fs/open.c
>> +++ b/fs/open.c
>> @@ -214,10 +214,9 @@ int do_truncate(struct dentry *dentry, loff_t length, unsigned int time_attrs,
>>  		newattrs.ia_valid |= ATTR_FILE;
>>  	}
>>  
>> +	mutex_lock(&dentry->d_inode->i_mutex);
>>  	/* Remove suid/sgid on truncate too */
>>  	newattrs.ia_valid |= should_remove_suid(dentry);
>> -
>> -	mutex_lock(&dentry->d_inode->i_mutex);
>>  	err = notify_change(dentry, &newattrs);
>>  	mutex_unlock(&dentry->d_inode->i_mutex);
>>  	return err;
>
> OK, I give up.  What race?
i_mode read not protected by i_mutex in should_remove_suid() and we
may have race condition with chown(). Sorry, seems I've been too crazy
about this. The truth is:
1: No one will call truncate() and chown() concurrently.
2: This race is still possible regardless to this fix.

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

end of thread, other threads:[~2008-10-27  7:58 UTC | newest]

Thread overview: 3+ messages (download: mbox.gz / follow: Atom feed)
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2008-10-15 19:35 [PATCH] vfs: Fix possible chmod/truncate race condition Dmitri Monakhov
2008-10-27  3:37 ` Andrew Morton
2008-10-27  7:57   ` Dmitri Monakhov

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