[libvirt] [PATCH] qemu: fix crash with shared disks

[Ján Tomko]

Commit f36a94f introduced a double free on all success paths
in qemuSharedDeviceEntryInsert.

Only call qemuSharedDeviceEntryFree on the error path and
set entry to NULL before jumping there if the entry already
is in the hash table.

https://bugzilla.redhat.com/show_bug.cgi?id=1142722
---
 src/qemu/qemu_conf.c | 26 ++++++++++++--------------
 1 file changed, 12 insertions(+), 14 deletions(-)

diff --git a/src/qemu/qemu_conf.c b/src/qemu/qemu_conf.c
index ac10b64..adc6caf 100644
--- a/src/qemu/qemu_conf.c
+++ b/src/qemu/qemu_conf.c
@@ -1011,38 +1011,36 @@ qemuSharedDeviceEntryInsert(virQEMUDriverPtr driver,
                             const char *name)
 {
     qemuSharedDeviceEntry *entry = NULL;
-    int ret = -1;
 
     if ((entry = virHashLookup(driver->sharedDevices, key))) {
         /* Nothing to do if the shared scsi host device is already
          * recorded in the table.
          */
-        if (qemuSharedDeviceEntryDomainExists(entry, name, NULL)) {
-            ret = 0;
-            goto cleanup;
+        if (!qemuSharedDeviceEntryDomainExists(entry, name, NULL)) {
+            if (VIR_EXPAND_N(entry->domains, entry->ref, 1) < 0 ||
+                VIR_STRDUP(entry->domains[entry->ref - 1], name) < 0) {
+                /* entry is owned by the hash table here */
+                entry = NULL;
+                goto error;
+            }
         }
-
-        if (VIR_EXPAND_N(entry->domains, entry->ref, 1) < 0 ||
-            VIR_STRDUP(entry->domains[entry->ref - 1], name) < 0)
-            goto cleanup;
     } else {
         if (VIR_ALLOC(entry) < 0 ||
             VIR_ALLOC_N(entry->domains, 1) < 0 ||
             VIR_STRDUP(entry->domains[0], name) < 0)
-            goto cleanup;
+            goto error;
 
         entry->ref = 1;
 
         if (virHashAddEntry(driver->sharedDevices, key, entry))
-            goto cleanup;
+            goto error;
     }
 
-    ret = 0;
+    return 0;
 
- cleanup:
+ error:
     qemuSharedDeviceEntryFree(entry, NULL);
-
-    return ret;
+    return -1;
 }
 
 
-- 
1.8.5.5