[PATCH] qemu: code protection for qemuBlockJobEventProcessLegacy

[huangy81 at chinatelecom.cn]

From: Chongyun Wu <wucy11 at chinatelecom.cn>

pointer disk might be null in some special cases or new
usage scenarios, therefore code protection is needed to
prevent segment faults.

Signed-off-by: Chongyun Wu <wucy11 at chinatelecom.cn>
---
 src/qemu/qemu_blockjob.c | 43 ++++++++++++++++++++++++-------------------
 1 file changed, 24 insertions(+), 19 deletions(-)

diff --git a/src/qemu/qemu_blockjob.c b/src/qemu/qemu_blockjob.c
index faf9a9f..00506b9 100644
--- a/src/qemu/qemu_blockjob.c
+++ b/src/qemu/qemu_blockjob.c
@@ -781,12 +781,13 @@ qemuBlockJobEventProcessLegacy(virQEMUDriver *driver,
 {
     virDomainDiskDef *disk = job->disk;
 
-    VIR_DEBUG("disk=%s, mirrorState=%s, type=%d, state=%d, newstate=%d",
-              disk->dst,
-              NULLSTR(virDomainDiskMirrorStateTypeToString(disk->mirrorState)),
-              job->type,
-              job->state,
-              job->newstate);
+    if (disk)
+        VIR_DEBUG("disk=%s, mirrorState=%s, type=%d, state=%d, newstate=%d",
+                  disk->dst,
+                  NULLSTR(virDomainDiskMirrorStateTypeToString(disk->mirrorState)),
+                  job->type,
+                  job->state,
+                  job->newstate);
 
     if (job->newstate == -1)
         return;
@@ -804,26 +805,30 @@ qemuBlockJobEventProcessLegacy(virQEMUDriver *driver,
         break;
 
     case VIR_DOMAIN_BLOCK_JOB_READY:
-        disk->mirrorState = VIR_DOMAIN_DISK_MIRROR_STATE_READY;
-        qemuDomainSaveStatus(vm);
+        if (disk) {
+            disk->mirrorState = VIR_DOMAIN_DISK_MIRROR_STATE_READY;
+            qemuDomainSaveStatus(vm);
+        }
         break;
 
     case VIR_DOMAIN_BLOCK_JOB_FAILED:
     case VIR_DOMAIN_BLOCK_JOB_CANCELED:
-        if (disk->mirror) {
-            virDomainLockImageDetach(driver->lockManager, vm, disk->mirror);
+        if (disk) {
+            if (disk->mirror) {
+                virDomainLockImageDetach(driver->lockManager, vm, disk->mirror);
 
-            /* Ideally, we would restore seclabels on the backing chain here
-             * but we don't know if somebody else is not using parts of it.
-             * Remove security driver metadata so that they are not leaked. */
-            qemuBlockRemoveImageMetadata(driver, vm, disk->dst, disk->mirror);
+                /* Ideally, we would restore seclabels on the backing chain here
+                 * but we don't know if somebody else is not using parts of it.
+                 * Remove security driver metadata so that they are not leaked. */
+                qemuBlockRemoveImageMetadata(driver, vm, disk->dst, disk->mirror);
 
-            virObjectUnref(disk->mirror);
-            disk->mirror = NULL;
+                virObjectUnref(disk->mirror);
+                disk->mirror = NULL;
+            }
+            disk->mirrorState = VIR_DOMAIN_DISK_MIRROR_STATE_NONE;
+            disk->mirrorJob = VIR_DOMAIN_BLOCK_JOB_TYPE_UNKNOWN;
+            qemuBlockJobUnregister(job, vm);
         }
-        disk->mirrorState = VIR_DOMAIN_DISK_MIRROR_STATE_NONE;
-        disk->mirrorJob = VIR_DOMAIN_BLOCK_JOB_TYPE_UNKNOWN;
-        qemuBlockJobUnregister(job, vm);
         break;
 
     case VIR_DOMAIN_BLOCK_JOB_LAST:
-- 
1.8.3.1