Buffer overflow in hw/scsi-disk.c in the SCSI subsystem in QEMU before 0.15.2, as used by Xen, might allow local guest users with permission to access the CD-ROM to cause a denial of service (guest crash) via a crafted SAI READ CAPACITY SCSI command. NOTE: this is only a vulnerability when root has manually modified certain permissions or ACLs.

The remote Oracle Linux 5 host has packages installed that are affected by a vulnerability as referenced in the ELSA-2011-1401 advisory.

    [3.0.3-132.el5_7.2]
    - Release device backends before restarting guest on the destination machine (rhbz 743850)
    - Fix SCSI buffer overflow and disable SCSI CD-ROMs (rhbz 736289)

    [3.0.3-132.el5_7.1]
    - hotplug: set netback/tap MTU to the same value as the bridge MTU (rhbz 738608)
    - copy the MTU of the physical interface to the Xen bridge (rhbz 738610)

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

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

The xen packages contain administration tools and the xend service for managing the kernel-xen kernel for virtualization on Scientific Linux.

A buffer overflow flaw was found in the Xen hypervisor SCSI subsystem emulation. An unprivileged, local guest user could provide a large number of bytes that are used to zero out a fixed-sized buffer via a SAI READ CAPACITY SCSI command, overwriting memory and causing the guest to crash. (CVE-2011-3346)

This update also fixes the following bugs :

  - Prior to this update, the vif-bridge script used a     maximum transmission unit (MTU) of 1500 for a new     Virtual Interface (VIF). As a result, the MTU of the VIF     could differ from that of the target bridge. This update     fixes the VIF hot-plug script so that the default MTU     for new VIFs will match that of the target Xen     hypervisor bridge. In combination with a new enough     kernel, this enables the use of jumbo frames in Xen     hypervisor guests.

  - Prior to this update, the network-bridge script set the     MTU of the bridge to 1500. As a result, the MTU of the     Xen hypervisor bridge could differ from that of the     physical interface. This update fixes the network script     so the MTU of the bridge can be set higher than 1500,     thus also providing support for jumbo frames. Now, the     MTU of the Xen hypervisor bridge will match that of the     physical interface.

  - Scientific Linux 5.6 introduced an optimized migration     handling that speeds up the migration of guests with     large memory. However, the new migration procedure can     theoretically cause data corruption. While no cases were     observed in practice, with this update, the xend daemon     properly waits for correct device release before the     guest is started on a destination machine, thus fixing     this bug.

Note: Before a guest is using a new enough kernel, the MTU of the VIF will drop back to 1500 (if it was set higher) after migration.

All xen users are advised to upgrade to these updated packages, which contain backported patches to correct these issues. After installing the updated packages, the xend service must be restarted for this update to take effect.

The remote Redhat Enterprise Linux 5 host has packages installed that are affected by a vulnerability as referenced in the RHSA-2011:1401 advisory.

  - qemu: local DoS with SCSI CD-ROM (CVE-2011-3346)

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

Updated xen packages that fix one security issue and three bugs are now available for Red Hat Enterprise Linux 5.

The Red Hat Security Response Team has rated this update as having moderate security impact. A Common Vulnerability Scoring System (CVSS) base score, which gives a detailed severity rating, is available from the CVE link in the References section.

The xen packages contain administration tools and the xend service for managing the kernel-xen kernel for virtualization on Red Hat Enterprise Linux.

A buffer overflow flaw was found in the Xen hypervisor SCSI subsystem emulation. An unprivileged, local guest user could provide a large number of bytes that are used to zero out a fixed-sized buffer via a SAI READ CAPACITY SCSI command, overwriting memory and causing the guest to crash. (CVE-2011-3346)

This update also fixes the following bugs :

* Prior to this update, the vif-bridge script used a maximum transmission unit (MTU) of 1500 for a new Virtual Interface (VIF). As a result, the MTU of the VIF could differ from that of the target bridge. This update fixes the VIF hot-plug script so that the default MTU for new VIFs will match that of the target Xen hypervisor bridge.
In combination with a new enough kernel (RHSA-2011:1386), this enables the use of jumbo frames in Xen hypervisor guests. (BZ#738608)

* Prior to this update, the network-bridge script set the MTU of the bridge to 1500. As a result, the MTU of the Xen hypervisor bridge could differ from that of the physical interface. This update fixes the network script so the MTU of the bridge can be set higher than 1500, thus also providing support for jumbo frames. Now, the MTU of the Xen hypervisor bridge will match that of the physical interface.
(BZ#738610)

* Red Hat Enterprise Linux 5.6 introduced an optimized migration handling that speeds up the migration of guests with large memory.
However, the new migration procedure can theoretically cause data corruption. While no cases were observed in practice, with this update, the xend daemon properly waits for correct device release before the guest is started on a destination machine, thus fixing this bug. (BZ#743850)

Note: Before a guest is using a new enough kernel (RHSA-2011:1386), the MTU of the VIF will drop back to 1500 (if it was set higher) after migration.

All xen users are advised to upgrade to these updated packages, which contain backported patches to correct these issues. After installing the updated packages, the xend service must be restarted for this update to take effect.

ID	Name	Product	Family	Severity
74540	openSUSE Security Update : kvm (openSUSE-2011-95)	Nessus	SuSE Local Security Checks	medium
68378	Oracle Linux 5 : xen (ELSA-2011-1401)	Nessus	Oracle Linux Local Security Checks	medium
61163	Scientific Linux Security Update : xen on SL5.x i386/x86_64	Nessus	Scientific Linux Local Security Checks	medium
56628	RHEL 5 : xen (RHSA-2011:1401)	Nessus	Red Hat Local Security Checks	medium
56621	CentOS 5 : xen (CESA-2011:1401)	Nessus	CentOS Local Security Checks	medium

Detections

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CVE-2011-3346

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Tenable Plugins

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