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Re: [libvirt] [PATCH 3/3] parallels: fix possible crash in case of errors in prlsdkLoadDomain



21.05.2015 10:29, Dmitry Guryanov пишет:
Sorry for top-posting,
Check code of virDomainObjListAdd. It assigns xmlopt->privateData->free to dom->privateDataFreeFunc.
I don't see why we can't do it manually, while problem the patch fixes is a bit different. We create three objects within this function: 'def', 'privdom', and 'dom'. On error path depending on the place where we failed, we need to use different scenarios to cleanup: delete all we allocated and not to do it twice. The code without the patch frees 'def' and 'pdom 'structures twice. In other words, if we didn't manage to assign 'pdom' to 'dom' because we failed earlier we should call privateDataFree function manully, and if we didn't set 'def' to 'dom', either new or existed one, we should free it manually too. Otherwise cleanup will be made by virDomainObjListRemove. Using xmlopt can't fix described problems.

________________________________________
От: Maxim Nestratov
Отправлено: 21 мая 2015 г. 10:17
Кому: Dmitry Guryanov; Maxim Nestratov; libvir-list redhat com; Dmitry Guryanov
Тема: Re: [PATCH 3/3] parallels: fix possible crash in case of errors in prlsdkLoadDomain

21.05.2015 10:04, Dmitry Guryanov пишет:

On 05/18/2015 05:44 PM, Maxim Nestratov wrote:
Cleanup code in prlsdkLoadDomain doesn't take into account the fact
if private domain freeing function is assigned or not. In case it is,
we shouldn't call it manually because virDomainObjListRemove calls it.
Also, allocated def structure should be freed only if it's not
assigned to domain. Otherwise it will be called twice one time by
virDomainObjListRemove and the second by prlsdkLoadDomain itself.
Libvirt now can assign this pointer inside virDomainObjListAdd. I
think you just need to set virDomainXMLOptionPtr->privateData->free to
our prlsdkDomObjFreePrivate.
I didn't get you. We already assign this function to
dom->privateDataFreeFunc, and seems to the right place for this function.
You can give virDomainXMLPrivateDataCallbacks structure as second
argument of virDomainXMLOptionNew, and it will create appropriate
virDomainXMLOption structure.

Signed-off-by: Maxim Nestratov <mnestratov parallels com>
---
   src/parallels/parallels_sdk.c | 17 ++++++++++++++---
   1 file changed, 14 insertions(+), 3 deletions(-)

diff --git a/src/parallels/parallels_sdk.c
b/src/parallels/parallels_sdk.c
index 5c15e94..2f2574e 100644
--- a/src/parallels/parallels_sdk.c
+++ b/src/parallels/parallels_sdk.c
@@ -1379,10 +1379,21 @@ prlsdkLoadDomain(parallelsConnPtr privconn,
         return dom;
    error:
-    if (dom && !olddom)
+    if (dom && !olddom) {
+        /* Domain isn't persistent means that we haven't yet set
+         * prlsdkDomObjFreePrivate and should call it manually
+         */
+        if (!dom->persistent)
+            prlsdkDomObjFreePrivate(pdom);
+
           virDomainObjListRemove(privconn->domains, dom);
-    virDomainDefFree(def);
-    prlsdkDomObjFreePrivate(pdom);
+    }
+    /* Delete newly allocated def only if we haven't assigned it to
domain
+     * Otherwise we will end up with domain having invalid def
within it
+     */
+    if (!dom)
+        virDomainDefFree(def);
+
       return NULL;
   }


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