[Qemu-devel] [Bug 588803] Re: Image corruption during snapshot creation/deletion

[Launchpad Bug Tracker]

[Expired for QEMU because there has been no activity for 60 days.]

** Changed in: qemu
       Status: Incomplete => Expired

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https://bugs.launchpad.net/bugs/588803

Title:
  Image corruption during snapshot creation/deletion

Status in QEMU:
  Expired

Bug description:
  Hello,

  The creation/deletion of snapshots sometimes crashes and corrupts the
  VM image and provoke a segmentation fault in "strcmp", called from
  "bdrv_snapshot_find".

  Here is a patch that temporarily fixes that (it fixes the segfault but
  not its reason) :

  --- qemu-kvm-0.12.2-old/savevm.c      2010-01-18 19:48:25.000000000 +0100
  +++ qemu-kvm-0.12.2/savevm.c  2010-02-12 13:45:07.225644169 +0100
  @@ -1624,6 +1624,7 @@
       int nb_sns, i, ret;
   
       ret = -ENOENT;
  +     if (!name) return ret;
       nb_sns = bdrv_snapshot_list(bs, &sn_tab);
       if (nb_sns < 0)
           return ret;
  @@ -1649,6 +1650,8 @@
       QEMUSnapshotInfo sn1, *snapshot = &sn1;
       int ret;
   
  +     if (!name) return 0;
  +
       QTAILQ_FOREACH(dinfo, &drives, next) {
           bs = dinfo->bdrv;
           if (bdrv_can_snapshot(bs) &&
  @@ -1777,6 +1780,11 @@
       QTAILQ_FOREACH(dinfo, &drives, next) {
           bs1 = dinfo->bdrv;
           if (bdrv_has_snapshot(bs1)) {
  +                     if (!name) {
  +                             monitor_printf(mon, "Could not find snapshot 
'NULL' on "
  +                                                                             
   "device '%s'\n",
  +                                                                             
   bdrv_get_device_name(bs1));
  +                     }
               ret = bdrv_snapshot_goto(bs1, name);
               if (ret < 0) {
                   if (bs != bs1)
  @@ -1804,6 +1812,11 @@
           }
       }
   
  +     if (!name) {
  +             monitor_printf(mon, "VM state name is NULL\n");
  +             return -EINVAL;
  +     }
  +
       /* Don't even try to load empty VM states */
       ret = bdrv_snapshot_find(bs, &sn, name);
       if ((ret >= 0) && (sn.vm_state_size == 0))
  @@ -1840,6 +1853,11 @@
       QTAILQ_FOREACH(dinfo, &drives, next) {
           bs1 = dinfo->bdrv;
           if (bdrv_has_snapshot(bs1)) {
  +                     if (!name) {
  +                             monitor_printf(mon, "Could not find snapshot 
'NULL' on "
  +                                                                             
   "device '%s'\n",
  +                                                                             
   bdrv_get_device_name(bs1));
  +                     }
               ret = bdrv_snapshot_delete(bs1, name);
               if (ret < 0) {
                   if (ret == -ENOTSUP)

  
  The patch is very simple. Some checks on the variable "name" were missing in 
"savevm.c".

  Regards,

  Nicolas Grandjean
  Conix Security

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