fix savevm command without id or tag

savevm without id or tag segfaults in:

(gdb) bt
#0  0x00007f600a83bf8a in __strcmp_sse42 () from /lib64/libc.so.6
#1  0x00000000004745b6 in bdrv_snapshot_find (bs=<value optimized out>,
    sn_info=0x7fff996be280, name=0x0) at savevm.c:1631
#2  0x0000000000475c80 in del_existing_snapshots (name=<value optimized out>,
    mon=<value optimized out>) at savevm.c:1654
#3  do_savevm (name=<value optimized out>, mon=<value optimized out>)

Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
(cherry picked from commit f139a4125682ecd45d96c2d1523443d1be65405c)

diff --git a/savevm.c b/savevm.c
index aefe052cd3b691072887b49468c78512d1c967ff..cb4105a4bc6ec2838b589331ddc2b2a3f0e751a7 100644 (file)
--- a/savevm.c
+++ b/savevm.c
@@ -1696,7 +1696,7 @@ void do_savevm(Monitor *mon, const QDict *qdict)
     sn->vm_clock_nsec = qemu_get_clock(vm_clock);
 
     /* Delete old snapshots of the same name */
-    if (del_existing_snapshots(mon, name) < 0) {
+    if (name && del_existing_snapshots(mon, name) < 0) {
         goto the_end;
     }