[Pkg-virtualbox-devel] Bug#838766: virtualbox-qt: segfault while deleting a snapshot on a VM with two virtual hard drives

[Gianfranco Costamagna]

Hi,

>I am using VirtualBox (from the Debian repositories) for virtualisation. One of
>my VMs uses two virtual hard drives (Fixed-size VDIs of 120 GBytes each,
>visible to the guest as SATA drives). I am trying to delete the oldest snapshot
>on this VM, so the "original" (fixed-size) VDI files are to be modified as
>changes are merged back into them from the oldest "difference" VDIs. Snapshot
>deletion was triggered using the "delete snaphot" button in the QT GUI; the
>host system was freshly booted, and no VMs were running.
>VirtualBox merges the "difference" VDI back into the first fixed-size VDI. It
>then deletes the "difference" VDI from the host filesystem, but instead of
>working on the second virtual disk, the progress indicator just disappears. The
>snapshot is still visible; the Virtual media Manager lists the "difference" VDI
>that was just being deleted as "missing" (so obviously, the media registry was
>not updated).
>dmesg delivers the message "[  868.272600] DeleteSnap[2018]: segfault at 31 ip
>000000000052bf8c sp 00007fb4b7b6d9c0 error 4 in VBoxSVC[400000+482000]" (the
>precediung and following lines are not associated with VirtualBox). I have no
>hints of physical media errors in the kernel log, so I consider the hard drive
>as OK here.
>htop shows that I am now having a total of three active VirtualBox processes,
>which load two physical CPU cores at 100% each.
>
>The expected behaviour would have been that nothing crashes, the VirtualBox
>media registry is updated correctly, and the second virtual disk is processed
>as well. Then, the configuration file for this VM shall be updated according to
>the snapshot deletion, and the snapshot shall disappear from the snapshot tree.
>
>I restored the VM from a backup and tried again, with the same result (however,
>I did not check  dmesg and htop in the 2nd attempt).
>
>The last time I deleted snapshots for this VM was with VirtualBox 5.0.24; I did
>not have trouble there. VirtualBox 5.1.6 now shows the described behaviour.
>
>I have no problems with deleting snapshots for VMs that have only one virtual
>hard drive in VirtualBox 5.1.6, so this seems to be linked to the number of
>virtual drives.


can you please open an upstream ticket [1] and link it here?
I pinged upstream on irc, and they said they already got a similar email with a similar
bug report.
Having a ticket will allow me to see how/when the bug is fixed and close it eventually

thanks!

G.


[1] https://www.virtualbox.org/newticket