CVE-2018-7550

The load_multiboot function in hw/i386/multiboot.c in Quick Emulator (aka QEMU) allows local guest OS users to execute arbitrary code on the QEMU host via a mh_load_end_addr value greater than mh_bss_end_addr, which triggers an out-of-bounds read or write memory access.

This update for qemu fixes the following issues:

This update has the next round of Spectre v2 related patches, which now integrate with corresponding changes in libvirt. (CVE-2017-5715 bsc#1068032)

The January 2018 release of qemu initially addressed the Spectre v2 vulnerability for KVM guests by exposing the spec-ctrl feature for all x86 vcpu types, which was the quick and dirty approach, but not the proper solution.

We replaced our initial patch by the patches from upstream.

This update defines spec_ctrl and ibpb cpu feature flags as well as new cpu models which are clones of existing models with either -IBRS or -IBPB added to the end of the model name. These new vcpu models explicitly include the new feature(s), whereas the feature flags can be added to the cpu parameter as with other features. In short, for continued Spectre v2 protection, ensure that either the appropriate cpu feature flag is added to the QEMU command-line, or one of the new cpu models is used.

Although migration from older versions is supported, the new cpu features won't be properly exposed to the guest until it is restarted with the cpu features explicitly added. A reboot is insufficient.

A warning patch is added which attempts to detect a migration from a qemu version which had the quick and dirty fix (it only detects certain cases, but hopefully is helpful.) For additional information on Spectre v2 as it relates to QEMU, see: https://www.qemu.org/2018/02/14/qemu-2-11-1-and-spectre-update/

A patch is added to continue to detect Spectre v2 mitigation features (as shown by cpuid), and if found provide that feature to guests, even if running on older KVM (kernel) versions which do not yet expose that feature to QEMU. (bsc#1082276)

These two patches will be removed when we can reasonably assume everyone is running with the appropriate updates.

Spectre fixes for IBM Z Series were included by providing more hw features to guests (bsc#1076813)

Also security fixes for the following CVE issues are included:

• CVE-2017-17381: The Virtio Vring implementation in QEMU allowed local OS guest users to cause a denial of service (divide-by-zero error and QEMU process crash) by unsetting vring alignment while updating Virtio rings. (bsc#1071228)
• CVE-2017-16845: The PS2 driver in Qemu did not validate 'rptr' and 'count' values during guest migration, leading to out-of-bounds access. (bsc#1068613)
• CVE-2017-15119: The Network Block Device (NBD) server in Quick Emulator (QEMU), was vulnerable to a denial of service issue. It could occur if a client sent large option requests, making the server waste CPU time on reading up to 4GB per request. A client could use this flaw to keep the NBD server from serving other requests, resulting in DoS. (bsc#1070144)
• CVE-2017-18043: Integer overflow in the macro ROUND_UP (n, d) in Quick Emulator (Qemu) allowed a user to cause a denial of service (Qemu process crash). (bsc#1076775)
• CVE-2018-5683: The VGA driver in Qemu allowed local OS guest privileged users to cause a denial of service (out-of-bounds read and QEMU process crash) by leveraging improper memory address validation. (bsc#1076114)
• CVE-2018-7550: The multiboot functionality in Quick Emulator (aka QEMU) allowed local guest OS users to execute arbitrary code on the QEMU host via an out-of-bounds read or write memory access. (bsc#1083291)
• CVE-2017-15124: VNC server implementation in Quick Emulator (QEMU) was found to be vulnerable to an unbounded memory allocation issue, as it did not throttle the framebuffer updates sent to its client. If the client did not consume these updates, VNC server allocates growing memory to hold onto this data. A malicious remote VNC client could use this flaw to cause DoS to the server host. (bsc#1073489)

Additional bugs fixed:

• Fix pcihp for 1.6 and older machine types (bsc#1074572)
• Fix packaging dependencies (coreutils) for qemu-ksm package (bsc#1040202)

This update for qemu fixes the following issues:

This update has the next round of Spectre v2 related patches, which now integrate with corresponding changes in libvirt. (CVE-2017-5715 bsc#1068032)

The January 2018 release of qemu initially addressed the Spectre v2 vulnerability for KVM guests by exposing the spec-ctrl feature for all x86 vcpu types, which was the quick and dirty approach, but not the proper solution.

We replaced our initial patch by the patches from upstream.

This update defines spec_ctrl and ibpb cpu feature flags as well as new cpu models which are clones of existing models with either -IBRS or -IBPB added to the end of the model name. These new vcpu models explicitly include the new feature(s), whereas the feature flags can be added to the cpu parameter as with other features. In short, for continued Spectre v2 protection, ensure that either the appropriate cpu feature flag is added to the QEMU command-line, or one of the new cpu models is used.

Although migration from older versions is supported, the new cpu features won't be properly exposed to the guest until it is restarted with the cpu features explicitly added. A reboot is insufficient.

A warning patch is added which attempts to detect a migration from a qemu version which had the quick and dirty fix (it only detects certain cases, but hopefully is helpful.) For additional information on Spectre v2 as it relates to QEMU, see: https://www.qemu.org/2018/02/14/qemu-2-11-1-and-spectre-update/

A patch is added to continue to detect Spectre v2 mitigation features (as shown by cpuid), and if found provide that feature to guests, even if running on older KVM (kernel) versions which do not yet expose that feature to QEMU. (bsc#1082276)

These two patches will be removed when we can reasonably assume everyone is running with the appropriate updates.

Also security fixes for the following CVE issues are included:

• CVE-2017-15119: The Network Block Device (NBD) server in Quick Emulator (QEMU), was vulnerable to a denial of service issue. It could occur if a client sent large option requests, making the server waste CPU time on reading up to 4GB per request. A client could use this flaw to keep the NBD server from serving other requests, resulting in DoS. (bsc#1070144)
• CVE-2017-15124: VNC server implementation in Quick Emulator (QEMU) was found to be vulnerable to an unbounded memory allocation issue, as it did not throttle the framebuffer updates sent to its client. If the client did not consume these updates, VNC server allocates growing memory to hold onto this data. A malicious remote VNC client could use this flaw to cause DoS to the server host. (bsc#1073489)
• CVE-2017-16845: The PS2 driver in Qemu did not validate 'rptr' and 'count' values during guest migration, leading to out-of-bounds access. (bsc#1068613)
• CVE-2017-17381: The Virtio Vring implementation in QEMU allowed local OS guest users to cause a denial of service (divide-by-zero error and QEMU process crash) by unsetting vring alignment while updating Virtio rings. (bsc#1071228)
• CVE-2017-18030: A problem in the Cirrus driver in Qemu allowed local OS guest privileged users to cause a denial of service (out-of-bounds array access and QEMU process crash) via vectors related to negative pitch. (bsc#1076179)
• CVE-2017-18043: Integer overflow in the macro ROUND_UP (n, d) in Quick Emulator (Qemu) allowed a user to cause a denial of service (Qemu process crash). (bsc#1076775)
• CVE-2018-5683: The VGA driver in Qemu allowed local OS guest privileged users to cause a denial of service (out-of-bounds read and QEMU process crash) by leveraging improper memory address validation. (bsc#1076114)
• CVE-2018-7550: The multiboot functionality in Quick Emulator (aka QEMU) allowed local guest OS users to execute arbitrary code on the QEMU host via an out-of-bounds read or write memory access. (bsc#1083291)

Also the following bugs were fixed:

• Eliminate bogus use of CPUID_7_0_EDX_PRED_CMD…

This update for kvm fixes the following issues:

• This update has the next round of Spectre v2 related patches, which now integrates with corresponding changes in libvirt. A January 2018 release of qemu initially addressed the Spectre v2 vulnerability for KVM guests by exposing the spec-ctrl feature for all x86 vcpu types, which was the quick and dirty approach, but not the proper solution. We remove that initial patch and now rely on patches from upstream. This update defines spec_ctrl and ibpb cpu feature flags as well as new cpu models which are clones of existing models with either -IBRS or -IBPB added to the end of the model name. These new vcpu models explicitly include the new feature(s), whereas the feature flags can be added to the cpu parameter as with other features. In short, for continued Spectre v2 protection, ensure that either the appropriate cpu feature flag is added to the QEMU command-line, or one of the new cpu models is used. Although migration from older versions is supported, the new cpu features won't be properly exposed to the guest until it is restarted with the cpu features explicitly added. A reboot is insufficient.

• A warning patch is added which attempts to detect a migration from a qemu version which had the quick and dirty fix (it only detects certain cases, but hopefully is helpful.) For additional information on Spectre v2 as it relates to QEMU, see: https://www.qemu.org/2018/02/14/qemu-2-11-1-and-spectre-update/ (CVE-2017-5715 bsc#1068032)

• A patch is added to continue to detect Spectre v2 mitigation features (as shown by cpuid), and if found provide that feature to guests, even if running on older KVM (kernel) versions which do not yet expose that feature to QEMU. (bsc#1082276) These two patches will be removed when we can reasonably assume everyone is running with the appropriate updates.

• Security fixes for the following CVE issues: (bsc#1076114 CVE-2018-5683) (bsc#1083291 CVE-2018-7550)

• This patch is already included, add here for CVE track (bsc#1076179 CVE-2017-18030)

• Toolchain changes have cause the built size of pxe-virtio.rom to exceed 64K. Tweak rarely used strings in code to reduce size of the binary so it fits again.

• Eliminate bogus use of CPUID_7_0_EDX_PRED_CMD which we've carried since the initial Spectre v2 patch was added. EDX bit 27 of CPUID Leaf 07H, Sub-leaf 0 provides status on STIBP, and not the PRED_CMD MSR. Exposing the STIBP CPUID feature bit to the guest is wrong in general, since the VM doesn't directly control the scheduling of physical hyperthreads. This is left strictly to the L0 hypervisor.

This update for xen fixes several issues.

These security issues were fixed:

• CVE-2018-8897: Prevent mishandling of debug exceptions on x86 (XSA-260, bsc#1090820)
• Handle HPET timers in IO-APIC mode correctly to prevent malicious or buggy HVM guests from causing a hypervisor crash or potentially privilege escalation/information leaks (XSA-261, bsc#1090822)
• Prevent unbounded loop, induced by qemu allowing an attacker to permanently keep a physical CPU core busy (XSA-262, bsc#1090823)
• CVE-2018-10472: x86 HVM guest OS users (in certain configurations) were able to read arbitrary dom0 files via QMP live insertion of a CDROM, in conjunction with specifying the target file as the backing file of a snapshot (bsc#1089152).
• CVE-2018-10471: x86 PV guest OS users were able to cause a denial of service (out-of-bounds zero write and hypervisor crash) via unexpected INT 80 processing, because of an incorrect fix for CVE-2017-5754 (bsc#1089635).
• CVE-2018-7550: The load_multiboot function allowed local guest OS users to execute arbitrary code on the host via a mh_load_end_addr value greater than mh_bss_end_addr, which triggers an out-of-bounds read or write memory access (bsc#1083292).

This non-security issue was fixed:

• bsc#1072834: Prevent unchecked MSR access error
• bsc#1057493: Prevent DomU crashes
• bsc#1086107: Fixed problems with backports for XSA-246 and XSA-247

This update for xen fixes several issues.

These security issues were fixed:

• CVE-2018-8897: Prevent mishandling of debug exceptions on x86 (XSA-260, bsc#1090820)
• Handle HPET timers in IO-APIC mode correctly to prevent malicious or buggy HVM guests from causing a hypervisor crash or potentially privilege escalation/information leaks (XSA-261, bsc#1090822)
• Prevent unbounded loop, induced by qemu allowing an attacker to permanently keep a physical CPU core busy (XSA-262, bsc#1090823)
• CVE-2018-10472: x86 HVM guest OS users (in certain configurations) were able to read arbitrary dom0 files via QMP live insertion of a CDROM, in conjunction with specifying the target file as the backing file of a snapshot (bsc#1089152).
• CVE-2018-10471: x86 PV guest OS users were able to cause a denial of service (out-of-bounds zero write and hypervisor crash) via unexpected INT 80 processing, because of an incorrect fix for CVE-2017-5754 (bsc#1089635).
• CVE-2018-7550: The load_multiboot function allowed local guest OS users to execute arbitrary code on the host via a mh_load_end_addr value greater than mh_bss_end_addr, which triggers an out-of-bounds read or write memory access (bsc#1083292).

These non-security issues were fixed:

• bsc#1072834: Prevent unchecked MSR access error
• bsc#1035442: Increase the value of LIBXL_DESTROY_TIMEOUT from 10 to 100 seconds, allowing for more domUs to be shutdown in parallel
• bsc#1057493: Prevent DomU crash

This update for xen fixes several issues.

These security issues were fixed:

• CVE-2018-8897: Prevent mishandling of debug exceptions on x86 (XSA-260, bsc#1090820)
• Handle HPET timers in IO-APIC mode correctly to prevent malicious or buggy HVM guests from causing a hypervisor crash or potentially privilege escalation/information leaks (XSA-261, bsc#1090822)
• Prevent unbounded loop, induced by qemu allowing an attacker to permanently keep a physical CPU core busy (XSA-262, bsc#1090823)
• CVE-2018-10472: x86 HVM guest OS users (in certain configurations) were able to read arbitrary dom0 files via QMP live insertion of a CDROM, in conjunction with specifying the target file as the backing file of a snapshot (bsc#1089152).
• CVE-2018-10471: x86 PV guest OS users were able to cause a denial of service (out-of-bounds zero write and hypervisor crash) via unexpected INT 80 processing, because of an incorrect fix for CVE-2017-5754 (bsc#1089635).
• CVE-2018-7550: The load_multiboot function allowed local guest OS users to execute arbitrary code on the host via a mh_load_end_addr value greater than mh_bss_end_addr, which triggers an out-of-bounds read or write memory access (bsc#1083292).

This update for xen fixes several issues.

These security issues were fixed:

• CVE-2018-8897: Prevent mishandling of debug exceptions on x86 (XSA-260, bsc#1090820)
• Handle HPET timers in IO-APIC mode correctly to prevent malicious or buggy HVM guests from causing a hypervisor crash or potentially privilege escalation/information leaks (XSA-261, bsc#1090822)
• Prevent unbounded loop, induced by qemu allowing an attacker to permanently keep a physical CPU core busy (XSA-262, bsc#1090823)
• CVE-2018-10472: x86 HVM guest OS users (in certain configurations) were able to read arbitrary dom0 files via QMP live insertion of a CDROM, in conjunction with specifying the target file as the backing file of a snapshot (bsc#1089152).
• CVE-2018-10471: x86 PV guest OS users were able to cause a denial of service (out-of-bounds zero write and hypervisor crash) via unexpected INT 80 processing, because of an incorrect fix for CVE-2017-5754 (bsc#1089635).
• CVE-2018-7550: The load_multiboot function allowed local guest OS users to execute arbitrary code on the host via a mh_load_end_addr value greater than mh_bss_end_addr, which triggers an out-of-bounds read or write memory access (bsc#1083292).

This update for kvm fixes the following issues:

This update has the next round of Spectre v2 related patches, which now integrates with corresponding changes in libvirt. A January 2018 release of qemu initially addressed the Spectre v2 vulnerability for KVM guests by exposing the spec-ctrl feature for all x86 vcpu types, which was the quick and dirty approach, but not the proper solution. We remove that initial patch and now rely on patches from upstream. This update defines spec_ctrl and ibpb cpu feature flags as well as new cpu models which are clones of existing models with either -IBRS or -IBPB added to the end of the model name. These new vcpu models explicitly include the new feature(s), whereas the feature flags can be added to the cpu parameter as with other features. In short, for continued Spectre v2 protection, ensure that either the appropriate cpu feature flag is added to the QEMU command-line, or one of the new cpu models is used. Although migration from older versions is supported, the new cpu features won't be properly exposed to the guest until it is restarted with the cpu features explicitly added. A reboot is insufficient.

A warning patch is added which attempts to detect a migration from a qemu version which had the quick and dirty fix (it only detects certain cases, but hopefully is helpful.)

For additional information on Spectre v2 as it relates to QEMU, see: https://www.qemu.org/2018/02/14/qemu-2-11-1-and-spectre-update/

(CVE-2017-5715 bsc#1068032)

A patch is added to continue to detect Spectre v2 mitigation features (as shown by cpuid), and if found provide that feature to guests, even if running on older KVM (kernel) versions which do not yet expose that feature to QEMU. (bsc#1082276)

Additional security fixes:

• CVE-2018-5683: An out-of-bounds read in vga_draw_text routine was fixed which could lead to crashes or information leakage. (bsc#1076114)

• CVE-2018-7550: multiboot OOB access while loading kernel image was fixed that could lead to crashes (bsc#1083291)

• CVE-2017-18030: An out-of-bounds access in cirrus_invalidate_region routine could lead to crashes or information leakage (bsc#1076179)

• Eliminate bogus use of CPUID_7_0_EDX_PRED_CMD which we've carried since the initial Spectre v2 patch was added. EDX bit 27 of CPUID Leaf 07H, Sub-leaf 0 provides status on STIBP, and not the PRED_CMD MSR. Exposing the STIBP CPUID feature bit to the guest is wrong in general, since the VM doesn't directly control the scheduling of physical hyperthreads. This is left strictly to the L0 hypervisor.

This update for qemu to version 2.11.2 fixes the following issues:

Security issue fixed:

• CVE-2018-11806: Fix heap buffer overflow issue that can happen while reassembling fragmented datagrams (bsc#1096223).
• CVE-2018-3639: Mitigation functionality for Speculative Store Bypass issue in x86 (bsc#1087082).
• CVE-2018-7550: Fix out of bounds read and write memory access, potentially leading to code execution (bsc#1083291)

Bug fixes:

• bsc#1091695: SEV guest will not lauchh with qemu-system-x86_64 version 2.11.1.
• bsc#1094898: qemu-guest-agent service doesn't work in version Leap 15.0.
• bsc#1094725: virsh blockresize does not work with Xen qdisks.
• bsc#1094913: QEMU crashes when starting a guest with more than 7.999TB.

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 18.04 LTS. (CVE-2017-16845)

Cyrille Chatras 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. (CVE-2018-7550)

Ross Lagerwall 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. This issue only affected Ubuntu 17.10 and Ubuntu 18.04 LTS. (CVE-2018-7858)