Re: [Qemu-devel] [PATCH] qga: Fix handle fd leak in acquire_privilege()

[Yan Vugenfirer]

On May 20, 2014, at 10:46 PM, Michael Roth <address@hidden> wrote:

> Quoting Luiz Capitulino (2014-05-20 14:17:42)
>> On Mon, 19 May 2014 15:26:03 +0800
>> <address@hidden> wrote:
>> 
>>> From: Gonglei <address@hidden>
>>> 
>>> token should be closed in all conditions.
>>> So move CloseHandle(token) to "out" branch.
>> 
>> Looks good to me. Michael, are you going to pick this one?
> 
> Sure I'll queue it. Though i'm a bit surprised OpenProcessToken() will still
> return an open handle on failure. Is there any confirmation a handle is
> actually getting leaked here, as opposed to just returning a handle that's
> already been closed?

It won’t return a handle if it failed (I actually was going to reject the patch 
because of it) - but if you look closely at the code you will see error cases 
after OpenProcessToken was successful where we jump out of the if scope and 
then CloseHandle won’t be called.

Best regards,
Yan.

> 
> If it's the latter case we might end up closing it twice after the change,
> so just want to confirm.
> 
>> 
>>> 
>>> Signed-off-by: Wang Rui <address@hidden>
>>> Signed-off-by: Gonglei <address@hidden>
>>> ---
>>> qga/commands-win32.c | 6 ++++--
>>> 1 file changed, 4 insertions(+), 2 deletions(-)
>>> 
>>> diff --git a/qga/commands-win32.c b/qga/commands-win32.c
>>> index d793dd0..e769396 100644
>>> --- a/qga/commands-win32.c
>>> +++ b/qga/commands-win32.c
>>> @@ -31,7 +31,7 @@
>>> 
>>> static void acquire_privilege(const char *name, Error **errp)
>>> {
>>> -    HANDLE token;
>>> +    HANDLE token = NULL;
>>>     TOKEN_PRIVILEGES priv;
>>>     Error *local_err = NULL;
>>> 
>>> @@ -53,13 +53,15 @@ static void acquire_privilege(const char *name, Error 
>>> **errp)
>>>             goto out;
>>>         }
>>> 
>>> -        CloseHandle(token);
>>>     } else {
>>>         error_set(&local_err, QERR_QGA_COMMAND_FAILED,
>>>                   "failed to open privilege token");
>>>     }
>>> 
>>> out:
>>> +    if (token) {
>>> +        CloseHandle(token);
>>> +    }
>>>     if (local_err) {
>>>         error_propagate(errp, local_err);
>>>     }
> 
>