linux-kernel - Re: [PATCH] Fix mountpoint reference leakage in linkat

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Date:	Fri, 31 Jan 2014 16:13:19 -0500
From:	Oleg Drokin <green@...uxhacker.ru>
To:	Al Viro <viro@...IV.linux.org.uk>
Cc:	linux-kernel@...r.kernel.org, jlayton@...hat.com,
	linux-fsdevel@...r.kernel.org
Subject: Re: [PATCH] Fix mountpoint reference leakage in linkat


On Jan 31, 2014, at 4:03 PM, Al Viro wrote:
>> diff --git a/fs/namei.c b/fs/namei.c
>> index bcb838e..e620937 100644
>> --- a/fs/namei.c
>> +++ b/fs/namei.c
>> @@ -3931,6 +3931,7 @@ out_dput:
>> 			goto retry;
>> 	}
>> 	if (retry_estale(error, how)) {
>> +		path_put(&old_path);
>> 		how |= LOOKUP_REVAL;
>> 		goto retry;
>> 	}
> Umm...  That obviously can't be right - we have another goto retry
> in the same situation (see in your diff context).  I agree that
> we have a leak there, but you've fixed only a half of it.

Hm, you are right, I did not notice this other one somehow.

So, not to take any guesses, should I convert the other goto retry into
retry_deleg similar in style to what happens in rename and unlink, only
make retry)deleg label before call to the security_path_link?
After the call to the security_path_link?
Or would you prefer to just free old_path in both cases?

Bye,
    Oleg
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