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[PATCH] qom-qmp-cmds: fix two memleaks in qmp_object_add

Pan Nengyuan posted 1 patch 5 years, 8 months ago
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git fetch https://github.com/patchew-project/qemu tags/patchew/20200309092212.3249-1-pannengyuan@huawei.com
Maintainers: Paolo Bonzini <pbonzini@redhat.com>, Eduardo Habkost <ehabkost@redhat.com>, "Daniel P. Berrangé" <berrange@redhat.com>
There is a newer version of this series
qom/qom-qmp-cmds.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
[PATCH] qom-qmp-cmds: fix two memleaks in qmp_object_add
Posted by Pan Nengyuan 5 years, 8 months ago 
'type/id' forgot to free in qmp_object_add, this patch fix that.

The leak stack:
Direct leak of 84 byte(s) in 6 object(s) allocated from:
    #0 0x7fe2a5ebf768 in __interceptor_malloc (/lib64/libasan.so.5+0xef768)
    #1 0x7fe2a5044445 in g_malloc (/lib64/libglib-2.0.so.0+0x52445)
    #2 0x7fe2a505dd92 in g_strdup (/lib64/libglib-2.0.so.0+0x6bd92)
    #3 0x56344954e692 in qmp_object_add /mnt/sdb/qemu-new/qemu_test/qemu/qom/qom-qmp-cmds.c:258
    #4 0x563449960f5a in do_qmp_dispatch /mnt/sdb/qemu-new/qemu_test/qemu/qapi/qmp-dispatch.c:132
    #5 0x563449960f5a in qmp_dispatch /mnt/sdb/qemu-new/qemu_test/qemu/qapi/qmp-dispatch.c:175
    #6 0x563449498a30 in monitor_qmp_dispatch /mnt/sdb/qemu-new/qemu_test/qemu/monitor/qmp.c:145
    #7 0x56344949a64f in monitor_qmp_bh_dispatcher /mnt/sdb/qemu-new/qemu_test/qemu/monitor/qmp.c:234
    #8 0x563449a92a3a in aio_bh_call /mnt/sdb/qemu-new/qemu_test/qemu/util/async.c:136

Direct leak of 54 byte(s) in 6 object(s) allocated from:
    #0 0x7fe2a5ebf768 in __interceptor_malloc (/lib64/libasan.so.5+0xef768)
    #1 0x7fe2a5044445 in g_malloc (/lib64/libglib-2.0.so.0+0x52445)
    #2 0x7fe2a505dd92 in g_strdup (/lib64/libglib-2.0.so.0+0x6bd92)
    #3 0x56344954e6c4 in qmp_object_add /mnt/sdb/qemu-new/qemu_test/qemu/qom/qom-qmp-cmds.c:267
    #4 0x563449960f5a in do_qmp_dispatch /mnt/sdb/qemu-new/qemu_test/qemu/qapi/qmp-dispatch.c:132
    #5 0x563449960f5a in qmp_dispatch /mnt/sdb/qemu-new/qemu_test/qemu/qapi/qmp-dispatch.c:175
    #6 0x563449498a30 in monitor_qmp_dispatch /mnt/sdb/qemu-new/qemu_test/qemu/monitor/qmp.c:145
    #7 0x56344949a64f in monitor_qmp_bh_dispatcher /mnt/sdb/qemu-new/qemu_test/qemu/monitor/qmp.c:234
    #8 0x563449a92a3a in aio_bh_call /mnt/sdb/qemu-new/qemu_test/qemu/util/async.c:136

Fixes: 5f07c4d60d091320186e7b0edaf9ed2cc16b2d1e
Reported-by: Euler Robot <euler.robot@huawei.com>
Signed-off-by: Pan Nengyuan <pannengyuan@huawei.com>
---
 qom/qom-qmp-cmds.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/qom/qom-qmp-cmds.c b/qom/qom-qmp-cmds.c
index 49db926fcc..ac59ba1aa8 100644
--- a/qom/qom-qmp-cmds.c
+++ b/qom/qom-qmp-cmds.c
@@ -247,8 +247,8 @@ void qmp_object_add(QDict *qdict, QObject **ret_data, Error **errp)
     QDict *pdict;
     Visitor *v;
     Object *obj;
-    const char *type;
-    const char *id;
+    g_autofree const char *type = NULL;
+    g_autofree const char *id = NULL;
 
     type = qdict_get_try_str(qdict, "qom-type");
     if (!type) {
-- 
2.18.2
Re: [PATCH] qom-qmp-cmds: fix two memleaks in qmp_object_add
Posted by Markus Armbruster 5 years, 8 months ago 
Cc'ing Kevin in the hope of a review.

Pan Nengyuan <pannengyuan@huawei.com> writes:

> 'type/id' forgot to free in qmp_object_add, this patch fix that.
>
> The leak stack:
> Direct leak of 84 byte(s) in 6 object(s) allocated from:
>     #0 0x7fe2a5ebf768 in __interceptor_malloc (/lib64/libasan.so.5+0xef768)
>     #1 0x7fe2a5044445 in g_malloc (/lib64/libglib-2.0.so.0+0x52445)
>     #2 0x7fe2a505dd92 in g_strdup (/lib64/libglib-2.0.so.0+0x6bd92)
>     #3 0x56344954e692 in qmp_object_add /mnt/sdb/qemu-new/qemu_test/qemu/qom/qom-qmp-cmds.c:258
>     #4 0x563449960f5a in do_qmp_dispatch /mnt/sdb/qemu-new/qemu_test/qemu/qapi/qmp-dispatch.c:132
>     #5 0x563449960f5a in qmp_dispatch /mnt/sdb/qemu-new/qemu_test/qemu/qapi/qmp-dispatch.c:175
>     #6 0x563449498a30 in monitor_qmp_dispatch /mnt/sdb/qemu-new/qemu_test/qemu/monitor/qmp.c:145
>     #7 0x56344949a64f in monitor_qmp_bh_dispatcher /mnt/sdb/qemu-new/qemu_test/qemu/monitor/qmp.c:234
>     #8 0x563449a92a3a in aio_bh_call /mnt/sdb/qemu-new/qemu_test/qemu/util/async.c:136
>
> Direct leak of 54 byte(s) in 6 object(s) allocated from:
>     #0 0x7fe2a5ebf768 in __interceptor_malloc (/lib64/libasan.so.5+0xef768)
>     #1 0x7fe2a5044445 in g_malloc (/lib64/libglib-2.0.so.0+0x52445)
>     #2 0x7fe2a505dd92 in g_strdup (/lib64/libglib-2.0.so.0+0x6bd92)
>     #3 0x56344954e6c4 in qmp_object_add /mnt/sdb/qemu-new/qemu_test/qemu/qom/qom-qmp-cmds.c:267
>     #4 0x563449960f5a in do_qmp_dispatch /mnt/sdb/qemu-new/qemu_test/qemu/qapi/qmp-dispatch.c:132
>     #5 0x563449960f5a in qmp_dispatch /mnt/sdb/qemu-new/qemu_test/qemu/qapi/qmp-dispatch.c:175
>     #6 0x563449498a30 in monitor_qmp_dispatch /mnt/sdb/qemu-new/qemu_test/qemu/monitor/qmp.c:145
>     #7 0x56344949a64f in monitor_qmp_bh_dispatcher /mnt/sdb/qemu-new/qemu_test/qemu/monitor/qmp.c:234
>     #8 0x563449a92a3a in aio_bh_call /mnt/sdb/qemu-new/qemu_test/qemu/util/async.c:136
>
> Fixes: 5f07c4d60d091320186e7b0edaf9ed2cc16b2d1e
> Reported-by: Euler Robot <euler.robot@huawei.com>
> Signed-off-by: Pan Nengyuan <pannengyuan@huawei.com>
> ---
>  qom/qom-qmp-cmds.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/qom/qom-qmp-cmds.c b/qom/qom-qmp-cmds.c
> index 49db926fcc..ac59ba1aa8 100644
> --- a/qom/qom-qmp-cmds.c
> +++ b/qom/qom-qmp-cmds.c
> @@ -247,8 +247,8 @@ void qmp_object_add(QDict *qdict, QObject **ret_data, Error **errp)
>      QDict *pdict;
>      Visitor *v;
>      Object *obj;
> -    const char *type;
> -    const char *id;
> +    g_autofree const char *type = NULL;
> +    g_autofree const char *id = NULL;
>  
>      type = qdict_get_try_str(qdict, "qom-type");
>      if (!type) {
Re: [PATCH] qom-qmp-cmds: fix two memleaks in qmp_object_add
Posted by Igor Mammedov 5 years, 8 months ago 
On Mon, 9 Mar 2020 17:22:12 +0800
Pan Nengyuan <pannengyuan@huawei.com> wrote:

> 'type/id' forgot to free in qmp_object_add, this patch fix that.
> 
> The leak stack:
> Direct leak of 84 byte(s) in 6 object(s) allocated from:
>     #0 0x7fe2a5ebf768 in __interceptor_malloc (/lib64/libasan.so.5+0xef768)
>     #1 0x7fe2a5044445 in g_malloc (/lib64/libglib-2.0.so.0+0x52445)
>     #2 0x7fe2a505dd92 in g_strdup (/lib64/libglib-2.0.so.0+0x6bd92)
>     #3 0x56344954e692 in qmp_object_add /mnt/sdb/qemu-new/qemu_test/qemu/qom/qom-qmp-cmds.c:258
>     #4 0x563449960f5a in do_qmp_dispatch /mnt/sdb/qemu-new/qemu_test/qemu/qapi/qmp-dispatch.c:132
>     #5 0x563449960f5a in qmp_dispatch /mnt/sdb/qemu-new/qemu_test/qemu/qapi/qmp-dispatch.c:175
>     #6 0x563449498a30 in monitor_qmp_dispatch /mnt/sdb/qemu-new/qemu_test/qemu/monitor/qmp.c:145
>     #7 0x56344949a64f in monitor_qmp_bh_dispatcher /mnt/sdb/qemu-new/qemu_test/qemu/monitor/qmp.c:234
>     #8 0x563449a92a3a in aio_bh_call /mnt/sdb/qemu-new/qemu_test/qemu/util/async.c:136
> 
> Direct leak of 54 byte(s) in 6 object(s) allocated from:
>     #0 0x7fe2a5ebf768 in __interceptor_malloc (/lib64/libasan.so.5+0xef768)
>     #1 0x7fe2a5044445 in g_malloc (/lib64/libglib-2.0.so.0+0x52445)
>     #2 0x7fe2a505dd92 in g_strdup (/lib64/libglib-2.0.so.0+0x6bd92)
>     #3 0x56344954e6c4 in qmp_object_add /mnt/sdb/qemu-new/qemu_test/qemu/qom/qom-qmp-cmds.c:267
>     #4 0x563449960f5a in do_qmp_dispatch /mnt/sdb/qemu-new/qemu_test/qemu/qapi/qmp-dispatch.c:132
>     #5 0x563449960f5a in qmp_dispatch /mnt/sdb/qemu-new/qemu_test/qemu/qapi/qmp-dispatch.c:175
>     #6 0x563449498a30 in monitor_qmp_dispatch /mnt/sdb/qemu-new/qemu_test/qemu/monitor/qmp.c:145
>     #7 0x56344949a64f in monitor_qmp_bh_dispatcher /mnt/sdb/qemu-new/qemu_test/qemu/monitor/qmp.c:234
>     #8 0x563449a92a3a in aio_bh_call /mnt/sdb/qemu-new/qemu_test/qemu/util/async.c:136
> 
> Fixes: 5f07c4d60d091320186e7b0edaf9ed2cc16b2d1e
> Reported-by: Euler Robot <euler.robot@huawei.com>
> Signed-off-by: Pan Nengyuan <pannengyuan@huawei.com>
> ---
>  qom/qom-qmp-cmds.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/qom/qom-qmp-cmds.c b/qom/qom-qmp-cmds.c
> index 49db926fcc..ac59ba1aa8 100644
> --- a/qom/qom-qmp-cmds.c
> +++ b/qom/qom-qmp-cmds.c
> @@ -247,8 +247,8 @@ void qmp_object_add(QDict *qdict, QObject **ret_data, Error **errp)
>      QDict *pdict;
>      Visitor *v;
>      Object *obj;
> -    const char *type;
> -    const char *id;
> +    g_autofree const char *type = NULL;
> +    g_autofree const char *id = NULL;

not sure that's it's correct

qdict_get_try_str() returns the reference to a string within
the QDict, so caller who provided qdict should take care of
freeing it.

>  
>      type = qdict_get_try_str(qdict, "qom-type");
>      if (!type) {
Re: [PATCH] qom-qmp-cmds: fix two memleaks in qmp_object_add
Posted by Pan Nengyuan 5 years, 8 months ago 

On 3/9/2020 5:51 PM, Igor Mammedov wrote:
> On Mon, 9 Mar 2020 17:22:12 +0800
> Pan Nengyuan <pannengyuan@huawei.com> wrote:
> 
>> 'type/id' forgot to free in qmp_object_add, this patch fix that.
>>
>> The leak stack:
>> Direct leak of 84 byte(s) in 6 object(s) allocated from:
>>     #0 0x7fe2a5ebf768 in __interceptor_malloc (/lib64/libasan.so.5+0xef768)
>>     #1 0x7fe2a5044445 in g_malloc (/lib64/libglib-2.0.so.0+0x52445)
>>     #2 0x7fe2a505dd92 in g_strdup (/lib64/libglib-2.0.so.0+0x6bd92)
>>     #3 0x56344954e692 in qmp_object_add /mnt/sdb/qemu-new/qemu_test/qemu/qom/qom-qmp-cmds.c:258
>>     #4 0x563449960f5a in do_qmp_dispatch /mnt/sdb/qemu-new/qemu_test/qemu/qapi/qmp-dispatch.c:132
>>     #5 0x563449960f5a in qmp_dispatch /mnt/sdb/qemu-new/qemu_test/qemu/qapi/qmp-dispatch.c:175
>>     #6 0x563449498a30 in monitor_qmp_dispatch /mnt/sdb/qemu-new/qemu_test/qemu/monitor/qmp.c:145
>>     #7 0x56344949a64f in monitor_qmp_bh_dispatcher /mnt/sdb/qemu-new/qemu_test/qemu/monitor/qmp.c:234
>>     #8 0x563449a92a3a in aio_bh_call /mnt/sdb/qemu-new/qemu_test/qemu/util/async.c:136
>>
>> Direct leak of 54 byte(s) in 6 object(s) allocated from:
>>     #0 0x7fe2a5ebf768 in __interceptor_malloc (/lib64/libasan.so.5+0xef768)
>>     #1 0x7fe2a5044445 in g_malloc (/lib64/libglib-2.0.so.0+0x52445)
>>     #2 0x7fe2a505dd92 in g_strdup (/lib64/libglib-2.0.so.0+0x6bd92)
>>     #3 0x56344954e6c4 in qmp_object_add /mnt/sdb/qemu-new/qemu_test/qemu/qom/qom-qmp-cmds.c:267
>>     #4 0x563449960f5a in do_qmp_dispatch /mnt/sdb/qemu-new/qemu_test/qemu/qapi/qmp-dispatch.c:132
>>     #5 0x563449960f5a in qmp_dispatch /mnt/sdb/qemu-new/qemu_test/qemu/qapi/qmp-dispatch.c:175
>>     #6 0x563449498a30 in monitor_qmp_dispatch /mnt/sdb/qemu-new/qemu_test/qemu/monitor/qmp.c:145
>>     #7 0x56344949a64f in monitor_qmp_bh_dispatcher /mnt/sdb/qemu-new/qemu_test/qemu/monitor/qmp.c:234
>>     #8 0x563449a92a3a in aio_bh_call /mnt/sdb/qemu-new/qemu_test/qemu/util/async.c:136
>>
>> Fixes: 5f07c4d60d091320186e7b0edaf9ed2cc16b2d1e
>> Reported-by: Euler Robot <euler.robot@huawei.com>
>> Signed-off-by: Pan Nengyuan <pannengyuan@huawei.com>
>> ---
>>  qom/qom-qmp-cmds.c | 4 ++--
>>  1 file changed, 2 insertions(+), 2 deletions(-)
>>
>> diff --git a/qom/qom-qmp-cmds.c b/qom/qom-qmp-cmds.c
>> index 49db926fcc..ac59ba1aa8 100644
>> --- a/qom/qom-qmp-cmds.c
>> +++ b/qom/qom-qmp-cmds.c
>> @@ -247,8 +247,8 @@ void qmp_object_add(QDict *qdict, QObject **ret_data, Error **errp)
>>      QDict *pdict;
>>      Visitor *v;
>>      Object *obj;
>> -    const char *type;
>> -    const char *id;
>> +    g_autofree const char *type = NULL;
>> +    g_autofree const char *id = NULL;
> 
> not sure that's it's correct
> 
> qdict_get_try_str() returns the reference to a string within
> the QDict, so caller who provided qdict should take care of
> freeing it.
> 
>>  
>>      type = qdict_get_try_str(qdict, "qom-type");
>>      if (!type) {
> 

    type = qdict_get_try_str(qdict, "qom-type");
    if (!type) {
        error_setg(errp, QERR_MISSING_PARAMETER, "qom-type");
        return;
    } else {
        type = g_strdup(type);
        qdict_del(qdict, "qom-type");
    }

If type is not NULL, it will go to the else branch, type re-assign immediately.
And it's aslo in the scope, so the string within the QDict will not be freed.

> .
>
Re: [PATCH] qom-qmp-cmds: fix two memleaks in qmp_object_add
Posted by Daniel P. Berrangé 5 years, 8 months ago 
On Mon, Mar 09, 2020 at 10:51:45AM +0100, Igor Mammedov wrote:
> On Mon, 9 Mar 2020 17:22:12 +0800
> Pan Nengyuan <pannengyuan@huawei.com> wrote:
> 
> > 'type/id' forgot to free in qmp_object_add, this patch fix that.
> > 
> > The leak stack:
> > Direct leak of 84 byte(s) in 6 object(s) allocated from:
> >     #0 0x7fe2a5ebf768 in __interceptor_malloc (/lib64/libasan.so.5+0xef768)
> >     #1 0x7fe2a5044445 in g_malloc (/lib64/libglib-2.0.so.0+0x52445)
> >     #2 0x7fe2a505dd92 in g_strdup (/lib64/libglib-2.0.so.0+0x6bd92)
> >     #3 0x56344954e692 in qmp_object_add /mnt/sdb/qemu-new/qemu_test/qemu/qom/qom-qmp-cmds.c:258
> >     #4 0x563449960f5a in do_qmp_dispatch /mnt/sdb/qemu-new/qemu_test/qemu/qapi/qmp-dispatch.c:132
> >     #5 0x563449960f5a in qmp_dispatch /mnt/sdb/qemu-new/qemu_test/qemu/qapi/qmp-dispatch.c:175
> >     #6 0x563449498a30 in monitor_qmp_dispatch /mnt/sdb/qemu-new/qemu_test/qemu/monitor/qmp.c:145
> >     #7 0x56344949a64f in monitor_qmp_bh_dispatcher /mnt/sdb/qemu-new/qemu_test/qemu/monitor/qmp.c:234
> >     #8 0x563449a92a3a in aio_bh_call /mnt/sdb/qemu-new/qemu_test/qemu/util/async.c:136
> > 
> > Direct leak of 54 byte(s) in 6 object(s) allocated from:
> >     #0 0x7fe2a5ebf768 in __interceptor_malloc (/lib64/libasan.so.5+0xef768)
> >     #1 0x7fe2a5044445 in g_malloc (/lib64/libglib-2.0.so.0+0x52445)
> >     #2 0x7fe2a505dd92 in g_strdup (/lib64/libglib-2.0.so.0+0x6bd92)
> >     #3 0x56344954e6c4 in qmp_object_add /mnt/sdb/qemu-new/qemu_test/qemu/qom/qom-qmp-cmds.c:267
> >     #4 0x563449960f5a in do_qmp_dispatch /mnt/sdb/qemu-new/qemu_test/qemu/qapi/qmp-dispatch.c:132
> >     #5 0x563449960f5a in qmp_dispatch /mnt/sdb/qemu-new/qemu_test/qemu/qapi/qmp-dispatch.c:175
> >     #6 0x563449498a30 in monitor_qmp_dispatch /mnt/sdb/qemu-new/qemu_test/qemu/monitor/qmp.c:145
> >     #7 0x56344949a64f in monitor_qmp_bh_dispatcher /mnt/sdb/qemu-new/qemu_test/qemu/monitor/qmp.c:234
> >     #8 0x563449a92a3a in aio_bh_call /mnt/sdb/qemu-new/qemu_test/qemu/util/async.c:136
> > 
> > Fixes: 5f07c4d60d091320186e7b0edaf9ed2cc16b2d1e
> > Reported-by: Euler Robot <euler.robot@huawei.com>
> > Signed-off-by: Pan Nengyuan <pannengyuan@huawei.com>
> > ---
> >  qom/qom-qmp-cmds.c | 4 ++--
> >  1 file changed, 2 insertions(+), 2 deletions(-)
> > 
> > diff --git a/qom/qom-qmp-cmds.c b/qom/qom-qmp-cmds.c
> > index 49db926fcc..ac59ba1aa8 100644
> > --- a/qom/qom-qmp-cmds.c
> > +++ b/qom/qom-qmp-cmds.c
> > @@ -247,8 +247,8 @@ void qmp_object_add(QDict *qdict, QObject **ret_data, Error **errp)
> >      QDict *pdict;
> >      Visitor *v;
> >      Object *obj;
> > -    const char *type;
> > -    const char *id;
> > +    g_autofree const char *type = NULL;
> > +    g_autofree const char *id = NULL;
> 
> not sure that's it's correct
> 
> qdict_get_try_str() returns the reference to a string within
> the QDict, so caller who provided qdict should take care of
> freeing it.

This is correct, but two lines later we have  "type = g_strdup(type)".

IOW, the code is storing both a const and non-const string in the
same variable which is gross.

So there's definitely a leak, but this is also not the right way
to fix it.

To fix it, notice that g_strdup says

   "Duplicates a string. If str is NULL it returns NULL. The 
    returned string should be freed with g_free() when no longer
    needed."

IOW, instead of

    const char *type;

    type = qdict_get_try_str(qdict, "qom-type");
    if (!type) {
        error_setg(errp, QERR_MISSING_PARAMETER, "qom-type");
        return;
    } else {
        type = g_strdup(type);
        qdict_del(qdict, "qom-type");
    }

we want

    g_autofree char *type = NULL;

    type = g_strdup(qdict_get_try_str(qdict, "qom-type"));
    if (!type) {
        error_setg(errp, QERR_MISSING_PARAMETER, "qom-type");
        return;
    }

    qdict_del(qdict, "qom-type");

> >      type = qdict_get_try_str(qdict, "qom-type");
> >      if (!type) {




Regards,
Daniel
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Re: [PATCH] qom-qmp-cmds: fix two memleaks in qmp_object_add
Posted by Pan Nengyuan 5 years, 8 months ago 

On 3/9/2020 6:15 PM, Daniel P. Berrangé wrote:
> On Mon, Mar 09, 2020 at 10:51:45AM +0100, Igor Mammedov wrote:
>> On Mon, 9 Mar 2020 17:22:12 +0800
>> Pan Nengyuan <pannengyuan@huawei.com> wrote:
>>
>>> 'type/id' forgot to free in qmp_object_add, this patch fix that.
>>>
>>> The leak stack:
>>> Direct leak of 84 byte(s) in 6 object(s) allocated from:
>>>     #0 0x7fe2a5ebf768 in __interceptor_malloc (/lib64/libasan.so.5+0xef768)
>>>     #1 0x7fe2a5044445 in g_malloc (/lib64/libglib-2.0.so.0+0x52445)
>>>     #2 0x7fe2a505dd92 in g_strdup (/lib64/libglib-2.0.so.0+0x6bd92)
>>>     #3 0x56344954e692 in qmp_object_add /mnt/sdb/qemu-new/qemu_test/qemu/qom/qom-qmp-cmds.c:258
>>>     #4 0x563449960f5a in do_qmp_dispatch /mnt/sdb/qemu-new/qemu_test/qemu/qapi/qmp-dispatch.c:132
>>>     #5 0x563449960f5a in qmp_dispatch /mnt/sdb/qemu-new/qemu_test/qemu/qapi/qmp-dispatch.c:175
>>>     #6 0x563449498a30 in monitor_qmp_dispatch /mnt/sdb/qemu-new/qemu_test/qemu/monitor/qmp.c:145
>>>     #7 0x56344949a64f in monitor_qmp_bh_dispatcher /mnt/sdb/qemu-new/qemu_test/qemu/monitor/qmp.c:234
>>>     #8 0x563449a92a3a in aio_bh_call /mnt/sdb/qemu-new/qemu_test/qemu/util/async.c:136
>>>
>>> Direct leak of 54 byte(s) in 6 object(s) allocated from:
>>>     #0 0x7fe2a5ebf768 in __interceptor_malloc (/lib64/libasan.so.5+0xef768)
>>>     #1 0x7fe2a5044445 in g_malloc (/lib64/libglib-2.0.so.0+0x52445)
>>>     #2 0x7fe2a505dd92 in g_strdup (/lib64/libglib-2.0.so.0+0x6bd92)
>>>     #3 0x56344954e6c4 in qmp_object_add /mnt/sdb/qemu-new/qemu_test/qemu/qom/qom-qmp-cmds.c:267
>>>     #4 0x563449960f5a in do_qmp_dispatch /mnt/sdb/qemu-new/qemu_test/qemu/qapi/qmp-dispatch.c:132
>>>     #5 0x563449960f5a in qmp_dispatch /mnt/sdb/qemu-new/qemu_test/qemu/qapi/qmp-dispatch.c:175
>>>     #6 0x563449498a30 in monitor_qmp_dispatch /mnt/sdb/qemu-new/qemu_test/qemu/monitor/qmp.c:145
>>>     #7 0x56344949a64f in monitor_qmp_bh_dispatcher /mnt/sdb/qemu-new/qemu_test/qemu/monitor/qmp.c:234
>>>     #8 0x563449a92a3a in aio_bh_call /mnt/sdb/qemu-new/qemu_test/qemu/util/async.c:136
>>>
>>> Fixes: 5f07c4d60d091320186e7b0edaf9ed2cc16b2d1e
>>> Reported-by: Euler Robot <euler.robot@huawei.com>
>>> Signed-off-by: Pan Nengyuan <pannengyuan@huawei.com>
>>> ---
>>>  qom/qom-qmp-cmds.c | 4 ++--
>>>  1 file changed, 2 insertions(+), 2 deletions(-)
>>>
>>> diff --git a/qom/qom-qmp-cmds.c b/qom/qom-qmp-cmds.c
>>> index 49db926fcc..ac59ba1aa8 100644
>>> --- a/qom/qom-qmp-cmds.c
>>> +++ b/qom/qom-qmp-cmds.c
>>> @@ -247,8 +247,8 @@ void qmp_object_add(QDict *qdict, QObject **ret_data, Error **errp)
>>>      QDict *pdict;
>>>      Visitor *v;
>>>      Object *obj;
>>> -    const char *type;
>>> -    const char *id;
>>> +    g_autofree const char *type = NULL;
>>> +    g_autofree const char *id = NULL;
>>
>> not sure that's it's correct
>>
>> qdict_get_try_str() returns the reference to a string within
>> the QDict, so caller who provided qdict should take care of
>> freeing it.
> 
> This is correct, but two lines later we have  "type = g_strdup(type)".
> 
> IOW, the code is storing both a const and non-const string in the
> same variable which is gross.
> 
> So there's definitely a leak, but this is also not the right way
> to fix it.
> 
> To fix it, notice that g_strdup says
> 
>    "Duplicates a string. If str is NULL it returns NULL. The 
>     returned string should be freed with g_free() when no longer
>     needed."
> 
> IOW, instead of
> 
>     const char *type;
> 
>     type = qdict_get_try_str(qdict, "qom-type");
>     if (!type) {
>         error_setg(errp, QERR_MISSING_PARAMETER, "qom-type");
>         return;
>     } else {
>         type = g_strdup(type);
>         qdict_del(qdict, "qom-type");
>     }
> 
> we want
> 
>     g_autofree char *type = NULL;
> 
>     type = g_strdup(qdict_get_try_str(qdict, "qom-type"));
>     if (!type) {
>         error_setg(errp, QERR_MISSING_PARAMETER, "qom-type");
>         return;
>     }
> 
>     qdict_del(qdict, "qom-type");

Good points. Looks very clear.

Thanks.

> 
>>>      type = qdict_get_try_str(qdict, "qom-type");
>>>      if (!type) {
> 
> 
> 
> 
> Regards,
> Daniel
>

Patchew 2.1-devel-b67e4c2

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