In case of variable 'oldjob' (job structure) in
qemuProcessReconnect() the init function was not called and the
cb pointer was just copied from the existing job structure in
virDomainObjPreserveJob(). This caused that the job and oldjob
had the same pointer, which was later freed at the end of the
qemuProcessReconnect() function by automatic call to
virDomainObjClearJob().
This caused an invalid read in case of a daemon crash as the job
structure was trying to read cb which had been already freed.

This patch changes the copying to g_memdup that allocates
different pointer, which can be later safely freed.

Signed-off-by: Kristina Hanicova <khanicov@redhat.com>
---
 src/conf/virdomainjob.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/conf/virdomainjob.c b/src/conf/virdomainjob.c
index aca801af38..0c67e84ef1 100644
--- a/src/conf/virdomainjob.c
+++ b/src/conf/virdomainjob.c
@@ -210,7 +210,7 @@ virDomainObjPreserveJob(virDomainJobObj *currJob,
     if (currJob->cb && currJob->cb->allocJobPrivate &&
         !(currJob->privateData = currJob->cb->allocJobPrivate()))
         return -1;
-    job->cb = currJob->cb;
+    job->cb = g_memdup(currJob->cb, sizeof(*currJob->cb));
 
     virDomainObjResetJob(currJob);
     virDomainObjResetAsyncJob(currJob);
-- 
2.37.3

On 9/29/22 13:56, Kristina Hanicova wrote:
> In case of variable 'oldjob' (job structure) in
> qemuProcessReconnect() the init function was not called and the
> cb pointer was just copied from the existing job structure in
> virDomainObjPreserveJob(). This caused that the job and oldjob
> had the same pointer, which was later freed at the end of the
> qemuProcessReconnect() function by automatic call to
> virDomainObjClearJob().
> This caused an invalid read in case of a daemon crash as the job
> structure was trying to read cb which had been already freed.
> 
> This patch changes the copying to g_memdup that allocates
> different pointer, which can be later safely freed.
> 
> Signed-off-by: Kristina Hanicova <khanicov@redhat.com>
> ---
>  src/conf/virdomainjob.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 

Cleaned up the commit message a bit. Specifically, using
virDomainObjInitJob() wouldn't really help here, because job->cb and
currJob->cb would still share the same pointer after
virDomainObjPreserveJob() is called. In fact, it would lead to a memory
leak because the first thing that virDomainObjPreserveJob() does is
memset() job to 0.

Reviewed-by: Michal Privoznik <mprivozn@redhat.com>

and pushed.

Michal