Re: [PATCH v2 14/14] qga: Fix qmp_guest_suspend_{disk, ram}() error handling

[Markus Armbruster]

Philippe Mathieu-Daudé <address@hidden> writes:

> On 4/22/20 5:17 PM, Markus Armbruster wrote:
>> Philippe Mathieu-Daudé <address@hidden> writes:
>>
>>> On 4/22/20 3:07 PM, Markus Armbruster wrote:
>>>> The Error ** argument must be NULL, &error_abort, &error_fatal, or a
>>>> pointer to a variable containing NULL.  Passing an argument of the
>>>> latter kind twice without clearing it in between is wrong: if the
>>>> first call sets an error, it no longer points to NULL for the second
>>>>
>>>> qmp_guest_suspend_disk() and qmp_guest_suspend_ram() pass @local_err
>>>> first to check_suspend_mode(), then to acquire_privilege(), then to
>>>> execute_async().  Continuing after errors here can only end in tears.
>>>> For instance, we risk tripping error_setv()'s assertion.
>>>>
>>>> Fixes: aa59637ea1c6a4c83430933f9c44c43e6c3f1b69
>>>> Fixes: f54603b6aa765514b2519e74114a2f417759d727
>>>> Cc: Michael Roth <address@hidden>
>>>> Signed-off-by: Markus Armbruster <address@hidden>
>>>> ---
>>>>    qga/commands-win32.c | 14 ++++++++++++++
>>>>    1 file changed, 14 insertions(+)
>>>>
>>>> diff --git a/qga/commands-win32.c b/qga/commands-win32.c
>>>> index 9717a8d52d..5ba56327dd 100644
>>>> --- a/qga/commands-win32.c
>>>> +++ b/qga/commands-win32.c
>>>> @@ -1322,9 +1322,16 @@ void qmp_guest_suspend_disk(Error **errp)
>>>>          *mode = GUEST_SUSPEND_MODE_DISK;
>>>>        check_suspend_mode(*mode, &local_err);
>>>> +    if (local_err) {
>>>> +        goto out;
>>>> +    }
>>>>        acquire_privilege(SE_SHUTDOWN_NAME, &local_err);
>>>> +    if (local_err) {
>>>> +        goto out;
>>>> +    }
>>>>        execute_async(do_suspend, mode, &local_err);
>>>>    +out:
>>>>        if (local_err) {
>>>
>>> https://www.mail-archive.com/address@hidden/msg695647.html is
>>> slightly different by removing the if() check.
>>
>> It frees @mode unconditionally (marked --> below) I believe that's
>> wrong.  execute_async() runs do_suspend() in a new thread, and passes it
>> @mode.  do_suspend() frees it.
>
> Oops I missed that, good catch!
>
> Reviewed-by: Philippe Mathieu-Daudé <address@hidden>

Thanks!

I wasn't aware of (or totally forgot about) your patch, or else I'd have
fixed it instead of redoing it.  My apologies!