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virDomainFormatSchedDef: Avoid false positive NULL dereference

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Okay, I admit that our code here is complex. It's not easy to
spot that NULL deref can't really happen here. So it's no wonder
that a dumb compiler fails to see all the connections and
produces the following errors:

  CC       conf/libvirt_conf_la-domain_conf.lo
conf/domain_conf.c: In function 'virDomainDefFormatInternal':
conf/domain_conf.c:22162:22: error: potential null pointer dereference [-Werror=null-dereference]
             if (sched->policy == i)
                 ~~~~~^~~~~~~~
<snip/>
cc1: all warnings being treated as errors

Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
This commit is contained in:
Michal Privoznik 2016-06-02 12:19:57 +02:00
parent 09258c3c82
commit f916194c7e
1 changed files with 13 additions and 4 deletions
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17
src/conf/domain_conf.c
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@ -22140,6 +22140,14 @@ virDomainFormatSchedDef(virDomainDefPtr def,
size_t i;
int ret = -1;
/* Okay, @func should never return NULL here because it does
* so iff corresponding resource does not exists. But if it
* doesn't we should not have been called in the first place.
* But some compilers fails to see this complex reasoning and
* deduct that this code is buggy. Shut them up by checking
* for return value of sched. Even though we don't need to.
*/
if (!(schedMap = virBitmapNew(VIR_DOMAIN_CPUMASK_LEN)) ||
!(prioMap = virBitmapNew(VIR_DOMAIN_CPUMASK_LEN)))
goto cleanup;
@ -22152,7 +22160,7 @@ virDomainFormatSchedDef(virDomainDefPtr def,
while ((next = virBitmapNextSetBit(resourceMap, next)) > -1) {
sched = func(def, next);
if (sched->policy == i)
if (sched && sched->policy == i)
ignore_value(virBitmapSetBit(schedMap, next));
}
@ -22180,14 +22188,15 @@ virDomainFormatSchedDef(virDomainDefPtr def,
/* we need to find a subset of vCPUs with the given scheduler
* that share the priority */
nextprio = virBitmapNextSetBit(schedMap, -1);
sched = func(def, nextprio);
priority = sched->priority;
if (!(sched = func(def, nextprio)))
goto cleanup;
priority = sched->priority;
ignore_value(virBitmapSetBit(prioMap, nextprio));
while ((nextprio = virBitmapNextSetBit(schedMap, nextprio)) > -1) {
sched = func(def, nextprio);
if (sched->priority == priority)
if (sched && sched->priority == priority)
ignore_value(virBitmapSetBit(prioMap, nextprio));
}