Updated qemu-kvm packages that fix multiple security issues, several bugs, and add various enhancements are now available for Red Hat Enterprise Linux 7.

Red Hat Product Security has rated this update as having Important security impact. Common Vulnerability Scoring System (CVSS) base scores, which give detailed severity ratings, are available for each vulnerability from the CVE links in the References section.

KVM (Kernel-based Virtual Machine) is a full virtualization solution for Linux on AMD64 and Intel 64 systems. The qemu-kvm packages provide the user-space component for running virtual machines using KVM.

It was found that the Cirrus blit region checks were insufficient. A privileged guest user could use this flaw to write outside of VRAM-allocated buffer boundaries in the host's QEMU process address space with attacker-provided data. (CVE-2014-8106)

An uninitialized data structure use flaw was found in the way the set_pixel_format() function sanitized the value of bits_per_pixel. An attacker able to access a guest's VNC console could use this flaw to crash the guest. (CVE-2014-7815)

It was found that certain values that were read when loading RAM during migration were not validated. A user able to alter the savevm data (either on the disk or over the wire during migration) could use either of these flaws to corrupt QEMU process memory on the (destination) host, which could potentially result in arbitrary code execution on the host with the privileges of the QEMU process.
(CVE-2014-7840)

A NULL pointer dereference flaw was found in the way QEMU handled UDP packets with a source port and address of 0 when QEMU's user networking was in use. A local guest user could use this flaw to crash the guest. (CVE-2014-3640)

Red Hat would like to thank James Spadaro of Cisco for reporting CVE-2014-7815, and Xavier Mehrenberger and Stephane Duverger of Airbus for reporting CVE-2014-3640. The CVE-2014-8106 issue was found by Paolo Bonzini of Red Hat, and the CVE-2014-7840 issue was discovered by Michael S. Tsirkin of Red Hat.

Bug fixes :

* The KVM utility executed demanding routing update system calls every time it performed an MSI vector mask/unmask operation. Consequently, guests running legacy systems such as Red Hat Enterprise Linux 5 could, under certain circumstances, experience significant slowdown.
Now, the routing system calls during mask/unmask operations are skipped, and the performance of legacy guests is now more consistent.
(BZ#1098976)

* Due to a bug in the Internet Small Computer System Interface (iSCSI) driver, a qemu-kvm process terminated unexpectedly with a segmentation fault when the 'write same' command was executed in guest mode under the iSCSI protocol. This update fixes the bug, and the 'write same' command now functions in guest mode under iSCSI as intended.
(BZ#1083413)

* The QEMU command interface did not properly handle resizing of cache memory during guest migration, causing QEMU to terminate unexpectedly with a segmentation fault. This update fixes the related code, and QEMU no longer crashes in the described situation. (BZ#1066338)

Enhancements :

* The maximum number of supported virtual CPUs (vCPUs) in a KVM guest has been increased to 240. This increases the number of virtual processing units that the user can assign to the guest, and therefore improves its performance potential. (BZ#1134408)

* Support for the 5th Generation Intel Core processors has been added to the QEMU hypervisor, the KVM kernel code, and the libvirt API. This allows KVM guests to use the following instructions and features:
ADCX, ADOX, RDSFEED, PREFETCHW, and supervisor mode access prevention (SMAP). (BZ#1116117)

* The 'dump-guest-memory' command now supports crash dump compression.
This makes it possible for users who cannot use the 'virsh dump' command to require less hard disk space for guest crash dumps. In addition, saving a compressed guest crash dump frequently takes less time than saving a non-compressed one. (BZ#1157798)

* This update introduces support for flight recorder tracing, which uses SystemTap to automatically capture qemu-kvm data while the guest machine is running. For detailed instructions on how to configure and use flight recorder tracing, see the Virtualization Deployment and Administration Guide, linked to in the References section below.
(BZ#1088112)

The Linux/Unix host has one or more packages installed that are impacted by a vulnerability without a vendor supplied patch available.

  - The host_from_stream_offset function in arch_init.c in QEMU, when loading RAM during migration, allows     remote attackers to execute arbitrary code via a crafted (1) offset or (2) length value in savevm data.
    (CVE-2014-7840)

Note that Nessus relies on the presence of the package as reported by the vendor.

- Fix qemu-img convert corruption for unflushed files (bz     #1167249)

    - Fix SLES11 migration issue (bz #1109427)

    - CVE-2014-7840: insufficient parameter validation       during ram load (bz #1163080)

Note that Tenable Network Security has extracted the preceding description block directly from the Fedora security advisory. Tenable has attempted to automatically clean and format it as much as possible without introducing additional issues.

Updated qemu packages fix security vulnerabilities :

During migration, the values read from migration stream during ram load are not validated. Especially offset in host_from_stream_offset() and also the length of the writes in the callers of the said function.
A user able to alter the savevm data (either on the disk or over the wire during migration) could use either of these flaws to corrupt QEMU process memory on the (destination) host, which could potentially result in arbitrary code execution on the host with the privileges of the QEMU process (CVE-2014-7840).

Paolo Bonzini of Red Hat discovered that the blit region checks were insufficient in the Cirrus VGA emulator in qemu. A privileged guest user could use this flaw to write into qemu address space on the host, potentially escalating their privileges to those of the qemu host process (CVE-2014-8106).

The remote Ubuntu 14.04 LTS host has packages installed that are affected by multiple vulnerabilities as referenced in the USN-2439-1 advisory.

    Michael S. Tsirkin discovered that QEMU incorrectly handled certain parameters during ram load while     performing a migration. An attacker able to manipulate savevm data could use this issue to possibly     execute arbitrary code on the host. This issue only affected Ubuntu 12.04 LTS, Ubuntu 14.04 LTS, and     Ubuntu 14.10. (CVE-2014-7840)

    Paolo Bonzini discovered that QEMU incorrectly handled memory in the Cirrus VGA device. A malicious guest     could possibly use this issue to write into memory of the host, leading to privilege escalation.
    (CVE-2014-8106)

Tenable has extracted the preceding description block directly from the Ubuntu security advisory.

Note that Nessus has not tested for these issues but has instead relied only on the application's self-reported version number.

Updated qemu packages fix multiple security vulnerabilities :

Sibiao Luo discovered that QEMU incorrectly handled device hot-unplugging. A local user could possibly use this flaw to cause a denial of service (CVE-2013-4377).

Michael S. Tsirkin discovered that QEMU incorrectly handled vmxnet3 devices. A local guest could possibly use this issue to cause a denial of service, or possibly execute arbitrary code on the host (CVE-2013-4544).

Multiple integer overflow, input validation, logic error, and buffer overflow flaws were discovered in various QEMU block drivers. An attacker able to modify a disk image file loaded by a guest could use these flaws to crash the guest, or corrupt QEMU process memory on the host, potentially resulting in arbitrary code execution on the host with the privileges of the QEMU process (CVE-2014-0143, CVE-2014-0144, CVE-2014-0145, CVE-2014-0147).

A buffer overflow flaw was found in the way the virtio_net_handle_mac() function of QEMU processed guest requests to update the table of MAC addresses. A privileged guest user could use this flaw to corrupt QEMU process memory on the host, potentially resulting in arbitrary code execution on the host with the privileges of the QEMU process (CVE-2014-0150).

A divide-by-zero flaw was found in the seek_to_sector() function of the parallels block driver in QEMU. An attacker able to modify a disk image file loaded by a guest could use this flaw to crash the guest (CVE-2014-0142).

A NULL pointer dereference flaw was found in the QCOW2 block driver in QEMU. An attacker able to modify a disk image file loaded by a guest could use this flaw to crash the guest (CVE-2014-0146).

It was found that the block driver for Hyper-V VHDX images did not correctly calculate BAT (Block Allocation Table) entries due to a missing bounds check. An attacker able to modify a disk image file loaded by a guest could use this flaw to crash the guest (CVE-2014-0148).

An out-of-bounds memory access flaw was found in the way QEMU's IDE device driver handled the execution of SMART EXECUTE OFFLINE commands.
A privileged guest user could use this flaw to corrupt QEMU process memory on the host, which could potentially result in arbitrary code execution on the host with the privileges of the QEMU process (CVE-2014-2894).

Two integer overflow flaws were found in the QEMU block driver for QCOW version 1 disk images. A user able to alter the QEMU disk image files loaded by a guest could use either of these flaws to corrupt QEMU process memory on the host, which could potentially result in arbitrary code execution on the host with the privileges of the QEMU process (CVE-2014-0222, CVE-2014-0223).

Multiple buffer overflow, input validation, and out-of-bounds write flaws were found in the way the virtio, virtio-net, virtio-scsi, and usb drivers of QEMU handled state loading after migration. A user able to alter the savevm data (either on the disk or over the wire during migration) could use either of these flaws to corrupt QEMU process memory on the (destination) host, which could potentially result in arbitrary code execution on the host with the privileges of the QEMU process (CVE-2013-4148, CVE-2013-4151, CVE-2013-4535, CVE-2013-4536, CVE-2013-4541, CVE-2013-4542, CVE-2013-6399, CVE-2014-0182, CVE-2014-3461).

An information leak flaw was found in the way QEMU's VGA emulator accessed frame buffer memory for high resolution displays. A privileged guest user could use this flaw to leak memory contents of the host to the guest by setting the display to use a high resolution in the guest (CVE-2014-3615).

When guest sends udp packet with source port and source addr 0, uninitialized socket is picked up when looking for matching and already created udp sockets, and later passed to sosendto() where NULL pointer dereference is hit during so->slirp->vnetwork_mask.s_addr access Only guests using qemu user networking are affected (CVE-2014-3640).

The Advanced Threat Research team at Intel Security reported that guest provided parameter were insufficiently validated in rectangle functions in the vmware-vga driver. A privileged guest user could use this flaw to write into qemu address space on the host, potentially escalating their privileges to those of the qemu host process (CVE-2014-3689).

It was discovered that QEMU incorrectly handled USB xHCI controller live migration. An attacker could possibly use this issue to cause a denial of service, or possibly execute arbitrary code (CVE-2014-5263).

James Spadaro of Cisco reported insufficiently sanitized bits_per_pixel from the client in the QEMU VNC display driver. An attacker having access to the guest's VNC console could use this flaw to crash the guest (CVE-2014-7815).

During migration, the values read from migration stream during ram load are not validated. Especially offset in host_from_stream_offset() and also the length of the writes in the callers of the said function.
A user able to alter the savevm data (either on the disk or over the wire during migration) could use either of these flaws to corrupt QEMU process memory on the (destination) host, which could potentially result in arbitrary code execution on the host with the privileges of the QEMU process (CVE-2014-7840).

Paolo Bonzini of Red Hat discovered that the blit region checks were insufficient in the Cirrus VGA emulator in qemu. A privileged guest user could use this flaw to write into qemu address space on the host, potentially escalating their privileges to those of the qemu host process (CVE-2014-8106).

This update also provides usbredirparser 0.6 as a prerequisite of qemu-1.6.2

It was found that the Cirrus blit region checks were insufficient. A privileged guest user could use this flaw to write outside of VRAM- allocated buffer boundaries in the host's QEMU process address space with attacker-provided data. (CVE-2014-8106)

An uninitialized data structure use flaw was found in the way the set_pixel_format() function sanitized the value of bits_per_pixel. An attacker able to access a guest's VNC console could use this flaw to crash the guest. (CVE-2014-7815)

It was found that certain values that were read when loading RAM during migration were not validated. A user able to alter the savevm data (either on the disk or over the wire during migration) could use either of these flaws to corrupt QEMU process memory on the (destination) host, which could potentially result in arbitrary code execution on the host with the privileges of the QEMU process.
(CVE-2014-7840)

A NULL pointer dereference flaw was found in the way QEMU handled UDP packets with a source port and address of 0 when QEMU's user networking was in use. A local guest user could use this flaw to crash the guest. (CVE-2014-3640)

Bug fixes :

  - The KVM utility executed demanding routing update system     calls every time it performed an MSI vector mask/unmask     operation. Consequently, guests running legacy systems     such as Scientific Linux 5 could, under certain     circumstances, experience significant slowdown. Now, the     routing system calls during mask/unmask operations are     skipped, and the performance of legacy guests is now     more consistent.

  - Due to a bug in the Internet Small Computer System     Interface (iSCSI) driver, a qemu-kvm process terminated     unexpectedly with a segmentation fault when the 'write     same' command was executed in guest mode under the iSCSI     protocol. This update fixes the bug, and the 'write     same' command now functions in guest mode under iSCSI as     intended.

  - The QEMU command interface did not properly handle     resizing of cache memory during guest migration, causing     QEMU to terminate unexpectedly with a segmentation     fault. This update fixes the related code, and QEMU no     longer crashes in the described situation.

Enhancements :

  - The maximum number of supported virtual CPUs (vCPUs) in     a KVM guest has been increased to 240. This increases     the number of virtual processing units that the user can     assign to the guest, and therefore improves its     performance potential.

  - Support for the 5th Generation Intel Core processors has     been added to the QEMU hypervisor, the KVM kernel code,     and the libvirt API. This allows KVM guests to use the     following instructions and features: ADCX, ADOX,     RDSFEED, PREFETCHW, and supervisor mode access     prevention (SMAP).

  - The 'dump-guest-memory' command now supports crash dump     compression. This makes it possible for users who cannot     use the 'virsh dump' command to require less hard disk     space for guest crash dumps. In addition, saving a     compressed guest crash dump frequently takes less time     than saving a non-compressed one.

QEMU was updated to fix various bugs and security issues.

Following security issues were fixed: CVE-2014-8106: Heap-based buffer overflow in the Cirrus VGA emulator (hw/display/cirrus_vga.c) in QEMU allowed local guest users to execute arbitrary code via vectors related to blit regions.

  - CVE-2014-7840: The host_from_stream_offset function in     arch_init.c in QEMU, when loading RAM during migration,     allowed remote attackers to execute arbitrary code via a     crafted (1) offset or (2) length value in savevm data.

Also a bug was fixed where qemu-img convert could occasionaly corrupt images. (bsc#908380)

Note that Tenable Network Security has extracted the preceding description block directly from the SUSE security advisory. Tenable has attempted to automatically clean and format it as much as possible without introducing additional issues.

ID	名称	产品	系列	发布时间	最近更新时间	严重程度
81891	CentOS 7 : qemu-kvm (CESA-2015:0349)	Nessus	CentOS Local Security Checks	2015/3/18	2021/1/4	high
218555	Linux Distros Unpatched Vulnerability : CVE-2014-7840	Nessus	Misc.	2025/3/4	2025/8/18	critical
79912	Fedora 21 : qemu-2.1.2-7.fc21 (2014-16075)	Nessus	Fedora Local Security Checks	2014/12/15	2021/1/11	high
79994	Mandriva Linux Security Advisory : qemu (MDVSA-2014:249)	Nessus	Mandriva Local Security Checks	2014/12/15	2021/1/6	high
80026	Ubuntu 14.04 LTS : QEMU vulnerabilities (USN-2439-1)	Nessus	Ubuntu Local Security Checks	2014/12/15	2025/9/3	critical
80233	Fedora 20 : qemu-1.6.2-12.fc20 (2014-16626)	Nessus	Fedora Local Security Checks	2014/12/26	2021/1/11	high
81944	Mandriva Linux Security Advisory : qemu (MDVSA-2015:061)	Nessus	Mandriva Local Security Checks	2015/3/19	2021/1/6	high
82260	Scientific Linux Security Update : qemu-kvm on SL7.x x86_64 (20150305)	Nessus	Scientific Linux Local Security Checks	2015/3/26	2021/1/14	high
81632	RHEL 7 : qemu-kvm (RHSA-2015:0349)	Nessus	Red Hat Local Security Checks	2015/3/5	2019/10/24	high
83686	SUSE SLED12 / SLES12 Security Update : qemu (SUSE-SU-2015:0349-1)	Nessus	SuSE Local Security Checks	2015/5/20	2021/1/6	high

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