CVE-2023-34324

Closing of an event channel in the Linux kernel can result in a deadlock.
This happens when the close is being performed in parallel to an unrelated
Xen console action and the handling of a Xen console interrupt in an
unprivileged guest. The closing of an event channel is e.g. triggered by
removal of a paravirtual device on the other side. As this action will
cause console messages to be issued on the other side quite often, the
chance of triggering the deadlock is not neglectable. Note that 32-bit
Arm-guests are not affected, as the 32-bit Linux kernel on Arm doesn’t use
queued-RW-locks, which are required to trigger the issue (on Arm32 a
waiting writer doesn’t block further readers to get the lock).

Bugs

• <https://bugzilla.redhat.com/show_bug.cgi?id=2243164&gt;
• <https://bugzilla.suse.com/show_bug.cgi?id=1215745&gt;