Re: [Qemu-block] [Qemu-devel] [PATCH 12/15] gluster: Plug memory leaks in qemu_gluster_parse_json()

[Markus Armbruster]

Niels de Vos <address@hidden> writes:

> On Thu, Mar 02, 2017 at 10:44:03PM +0100, Markus Armbruster wrote:
>> To reproduce, run
>> 
>>     $ valgrind qemu-system-x86_64 --nodefaults -S --drive 
>> driver=gluster,volume=testvol,path=/a/b/c,server.0.type=xxx
>> 
>> Signed-off-by: Markus Armbruster <address@hidden>
>> ---
>>  block/gluster.c | 28 ++++++++++++++--------------
>>  1 file changed, 14 insertions(+), 14 deletions(-)
>> 
>> diff --git a/block/gluster.c b/block/gluster.c
>> index 6fbcf9e..35a7abb 100644
>> --- a/block/gluster.c
>> +++ b/block/gluster.c
>> @@ -480,7 +480,7 @@ static int 
>> qemu_gluster_parse_json(BlockdevOptionsGluster *gconf,
>>                                    QDict *options, Error **errp)
>>  {
>>      QemuOpts *opts;
>> -    GlusterServer *gsconf;
>> +    GlusterServer *gsconf = NULL;
>>      GlusterServerList *curr = NULL;
>>      QDict *backing_options = NULL;
>>      Error *local_err = NULL;
>> @@ -529,17 +529,16 @@ static int 
>> qemu_gluster_parse_json(BlockdevOptionsGluster *gconf,
>>          }
>>  
>>          ptr = qemu_opt_get(opts, GLUSTER_OPT_TYPE);
>> +        if (!ptr) {
>> +            error_setg(&local_err, QERR_MISSING_PARAMETER, 
>> GLUSTER_OPT_TYPE);
>> +            error_append_hint(&local_err, GERR_INDEX_HINT, i);
>> +            goto out;
>> +
>> +        }
>>          gsconf = g_new0(GlusterServer, 1);
>>          gsconf->type = qapi_enum_parse(GlusterTransport_lookup, ptr,
>> -                                       GLUSTER_TRANSPORT__MAX,
>> -                                       GLUSTER_TRANSPORT__MAX,
>> +                                       GLUSTER_TRANSPORT__MAX, 0,
>
> What is the reason to set the default to 0 and not the more readable
> GLUSTER_TRANSPORT_UNIX?

I chose 0 because the actual value must not matter: we don't want a
default here.

qapi_enum_parse() returns this argument when ptr isn't found.  If ptr is
non-null, it additionally sets an error.  Since ptr can't be null here,
the argument is only returned together with an error.  But then we won't
use *gsconf.

Do you think -1 instead of 0 would be clearer?

>>                                         &local_err);
>> -        if (!ptr) {
>> -            error_setg(&local_err, QERR_MISSING_PARAMETER, 
>> GLUSTER_OPT_TYPE);
>> -            error_append_hint(&local_err, GERR_INDEX_HINT, i);
>> -            goto out;
>> -
>> -        }
>>          if (local_err) {
>>              error_append_hint(&local_err,
>>                                "Parameter '%s' may be 'tcp' or 'unix'\n",
>> @@ -626,8 +625,10 @@ static int 
>> qemu_gluster_parse_json(BlockdevOptionsGluster *gconf,
>>              curr->next->value = gsconf;
>>              curr = curr->next;
>>          }
>> +        gsconf = NULL;
>>  
>> -        qdict_del(backing_options, str);
>> +        QDECREF(backing_options);
>> +        backing_options = NULL;
>>          g_free(str);
>>          str = NULL;
>>      }
>> @@ -636,11 +637,10 @@ static int 
>> qemu_gluster_parse_json(BlockdevOptionsGluster *gconf,
>>  
>>  out:
>>      error_propagate(errp, local_err);
>> +    qapi_free_GlusterServer(gsconf);
>>      qemu_opts_del(opts);
>> -    if (str) {
>> -        qdict_del(backing_options, str);
>> -        g_free(str);
>> -    }
>> +    g_free(str);
>> +    QDECREF(backing_options);
>>      errno = EINVAL;
>>      return -errno;
>>  }
>> -- 
>> 2.7.4
>> 
>>