USN-3575-2: QEMU regression

USN-3575-1 fixed vulnerabilities in QEMU. The fix for CVE-2017-11334 caused a regression in Xen environments. This update removes the problematic fix pending further investigation. We apologize for the inconvenience. Original advisory details: It was discovered that QEMU incorrectly handled guest ram. A privileged attacker inside the guest could use this issue to cause QEMU to crash, resulting in a denial of service. This issue only affected Ubuntu 14.04 LTS and Ubuntu 16.04 LTS. (CVE-2017-11334) David Buchanan discovered that QEMU incorrectly handled the VGA device. A privileged attacker inside the guest could use this issue to cause QEMU to crash, resulting in a denial of service. This issue was only addressed in Ubuntu 17.10. (CVE-2017-13672) Thomas Garnier discovered that QEMU incorrectly handled multiboot. An attacker could use this issue to cause QEMU to crash, resulting in a denial of service, or possibly execute arbitrary code on the host. In the default installation, when QEMU is used with libvirt, attackers would be isolated by the libvirt AppArmor profile. This issue only affected Ubuntu 14.04 LTS and Ubuntu 16.04 LTS. (CVE-2017-14167) Tuomas Tynkkynen discovered that QEMU incorrectly handled VirtFS directory sharing. An attacker could use this issue to obtain sensitive information from host memory. (CVE-2017-15038) Eric Blake discovered that QEMU incorrectly handled memory in the NBD server. An attacker could use this issue to cause the NBD server to crash, resulting in a denial of service. This issue only affected Ubuntu 17.10. (CVE-2017-15118) Eric Blake discovered that QEMU incorrectly handled certain options to the NBD server. An attacker could use this issue to cause the NBD server to crash, resulting in a denial of service. This issue only affected Ubuntu 14.04 LTS and Ubuntu 16.04 LTS. (CVE-2017-15119) Daniel Berrange discovered that QEMU incorrectly handled the VNC server. A remote attacker could possibly use this issue to consume memory, resulting in a denial of service. This issue was only addressed in Ubuntu 17.10. (CVE-2017-15124) Carl Brassey discovered that QEMU incorrectly handled certain websockets. A remote attacker could possibly use this issue to consume memory, resulting in a denial of service. This issue only affected Ubuntu 17.10. (CVE-2017-15268) Guoxiang Niu discovered that QEMU incorrectly handled the Cirrus VGA device. A privileged attacker inside the guest could use this issue to cause QEMU to crash, resulting in a denial of service. (CVE-2017-15289) Cyrille Chatras discovered that QEMU incorrectly handled certain PS2 values during migration. An attacker could possibly use this issue to cause QEMU to crash, resulting in a denial of service, or possibly execute arbitrary code. This issue only affected Ubuntu 16.04 LTS and Ubuntu 17.10. (CVE-2017-16845) It was discovered that QEMU incorrectly handled the Virtio Vring implementation. An attacker could possibly use this issue to cause QEMU to crash, resulting in a denial of service. This issue only affected Ubuntu 16.04 LTS and Ubuntu 17.10. (CVE-2017-17381) Eric Blake discovered that QEMU incorrectly handled certain rounding operations. An attacker could possibly use this issue to cause QEMU to crash, resulting in a denial of service. This issue only affected Ubuntu 14.04 LTS and Ubuntu 16.04 LTS. (CVE-2017-18043) Jiang Xin and Lin ZheCheng discovered that QEMU incorrectly handled the VGA device. A privileged attacker inside the guest could use this issue to cause QEMU to crash, resulting in a denial of service. (CVE-2018-5683)