[libvirt] [PATCH] PanicCheckABIStability: Need to check for existence

[John Ferlan]

Commit id '4313fead' added a call to virDomainPanicCheckABIStability()
which did not check whether the panic device existed before making a call
to virDomainDeviceInfoCheckABIStability() which ended up segfaulting:

Thread 1 (Thread 0x7f5332837700 (LWP 10964)):
    (src=<optimized out>, dst=<optimized out>)
    at conf/domain_conf.c:13007
    (dst=<optimized out>, src=<optimized out>)
    at conf/domain_conf.c:13712
    (src=<optimized out>, dst=<optimized out>)
    at conf/domain_conf.c:14056
    (domain=domain at entry=0x7f53000057c0, vm=vm at entry=0x7f53000036d0,
     defptr=defptr at entry=0x7f5332836978, snap=snap at entry=0x7f5332836970,
     update_current=update_current at entry=0x7f5332836962, flags=flags at entry=1)
    at conf/snapshot_conf.c:1230
    (domain=0x7f53000057c0, xmlDesc=<optimized out>, flags=1)
    at qemu/qemu_driver.c:12719
    (domain=domain at entry=0x7f53000057c0, xmlDesc=0x7f53000081d0
     "<domainsnapshot>\n  <name>snap2</name>\n
     <description>new-desc</description>\n  <state>running</state>\n
     <parent>\n    <name>snap1</name>\n  </parent>\n
     <creationTime>1387487268</creationTime>\n  <memory s"..., flags=1)
    at libvirt.c:19695
...

(gdb) up 3
(gdb) print *other->def->dom
$2 = {virtType = 2, id = -1, ..
...
  rng = 0x0, panic = 0x0, namespaceData = 0x0,...
...
(gdb) print *def->dom
$3 = {virtType = 2, id = -1, ...
...
  rng = 0x0, panic = 0x0, namespaceData = 0x0,...
...
(gdb)

Signed-off-by: John Ferlan <jferlan at redhat.com>
---

NOTE: Optionally the call could be changed to:

"if (src->panic && !virDomainPanicCheckABIStability(...)"

I went with what I did following the RNGDefCheckABIStability.

 src/conf/domain_conf.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/src/conf/domain_conf.c b/src/conf/domain_conf.c
index 0079234..c86af9a 100644
--- a/src/conf/domain_conf.c
+++ b/src/conf/domain_conf.c
@@ -13709,6 +13709,9 @@ static bool
 virDomainPanicCheckABIStability(virDomainPanicDefPtr src,
                                 virDomainPanicDefPtr dst)
 {
+    if (!src && !dst)
+        return true;
+
     return virDomainDeviceInfoCheckABIStability(&src->info, &dst->info);
 }
 
-- 
1.8.3.1