DSA-3981-1 linux -- security update

Several vulnerabilities have been discovered in the Linux kernel that may lead to privilege escalation, denial of service or information leaks. CVE-2017-7518 Andy Lutomirski discovered that KVM is prone to an incorrect debug exception (#DB) error occurring while emulating a syscall instruction. A process inside a guest can take advantage of this flaw for privilege escalation inside a guest. CVE-2017-7558 (stretch only) Stefano Brivio of Red Hat discovered that the SCTP subsystem is prone to a data leak vulnerability due to an out-of-bounds read flaw, allowing to leak up to 100 uninitialized bytes to userspace. CVE-2017-10661 (jessie only) Dmitry Vyukov of Google reported that the timerfd facility does not properly handle certain concurrent operations on a single file descriptor. This allows a local attacker to cause a denial of service or potentially execute arbitrary code. CVE-2017-11600 Bo Zhang reported that the xfrm subsystem does not properly validate one of the parameters to a netlink message. Local users with the CAP_NET_ADMIN capability can use this to cause a denial of service or potentially to execute arbitrary code. CVE-2017-12134 / #866511 / XSA-229 Jan H. Schoenherr of Amazon discovered that when Linux is running in a Xen PV domain on an x86 system, it may incorrectly merge block I/O requests. A buggy or malicious guest may trigger this bug in dom0 or a PV driver domain, causing a denial of service or potentially execution of arbitrary code. This issue can be mitigated by disabling merges on the underlying back-end block devices, e.g.: echo 2> /sys/block/nvme0n1/queue/nomerges CVE-2017-12146 (stretch only) Adrian Salido of Google reported a race condition in access to the driver_override attribute for platform devices in sysfs. If unprivileged users are permitted to access this attribute, this might allow them to gain privileges. CVE-2017-12153 Bo Zhang reported that the cfg80211 (wifi) subsystem does not properly validate the parameters to a netlink message. Local users with the CAP_NET_ADMIN capability (in any user namespace with a wifi device) can use this to cause a denial of service. CVE-2017-12154 Jim Mattson of Google reported that the KVM implementation for Intel x86 processors did not correctly handle certain nested hypervisor configurations. A malicious guest (or nested guest in a suitable L1 hypervisor) could use this for denial of service. CVE-2017-14106 Andrey Konovalov discovered that a user-triggerable division by zero in the tcp_disconnect() function could result in local denial of service. CVE-2017-14140 Otto Ebeling reported that the move_pages() system call performed insufficient validation of the UIDs of the calling and target processes, resulting in a partial ASLR bypass. This made it easier for local users to exploit vulnerabilities in programs installed with the set-UID permission bit set. CVE-2017-14156 sohu0106 reported an information leak in the atyfb video driver. A local user with access to a framebuffer device handled by this driver could use this to obtain sensitive information. CVE-2017-14340 Richard Wareing discovered that the XFS implementation allows the creation of files with the realtime flag on a filesystem with no realtime device, which can result in a crash (oops). A local user with access to an XFS filesystem that does not have a realtime device can use this for denial of service. CVE-2017-14489 ChunYu Wang of Red Hat discovered that the iSCSI subsystem does not properly validate the length of a netlink message, leading to memory corruption. A local user with permission to manage iSCSI devices can use this for denial of service or possibly to execute arbitrary code. CVE-2017-14497 (stretch only) Benjamin Poirier of SUSE reported that vnet headers are not properly handled within the tpacket_rcv() function in the raw packet (af_packet) feature. A local user with the CAP_NET_RAW capability can take advantage of this flaw to cause a denial of service (buffer overflow, and disk and memory corruption) or have other impact. CVE-2017-1000111 Andrey Konovalov of Google reported a race condition in the raw packet (af_packet) feature. Local users with the CAP_NET_RAW capability can use this for denial of service or possibly to execute arbitrary code. CVE-2017-1000112 Andrey Konovalov of Google reported a race condition flaw in the UDP Fragmentation Offload (UFO) code. A local user can use this flaw for denial of service or possibly to execute arbitrary code. CVE-2017-1000251 / #875881 Armis Labs discovered that the Bluetooth subsystem does not properly validate L2CAP configuration responses, leading to a stack buffer overflow. This is one of several vulnerabilities dubbed Blueborne. A nearby attacker can use this to cause a denial of service or possibly to execute arbitrary code on a system with Bluetooth enabled. CVE-2017-1000252 (stretch only) Jan H. Schoenherr of Amazon reported that the KVM implementation for Intel x86 processors did not correctly validate interrupt injection requests. A local user with permission to use KVM could use this for denial of service. CVE-2017-1000370 The Qualys Research Labs reported that a large argument or environment list can result in ASLR bypass for 32-bit PIE binaries. CVE-2017-1000371 The Qualys Research Labs reported that a large argument or environment list can result in a stack/heap clash for 32-bit PIE binaries. CVE-2017-1000380 Alexander Potapenko of Google reported a race condition in the ALSA (sound) timer driver, leading to an information leak. A local user with permission to access sound devices could use this to obtain sensitive information. Debian disables unprivileged user namespaces by default, but if they are enabled (via the kernel.unprivileged_userns_clone sysctl) then CVE-2017-11600, CVE-2017-14497 and CVE-2017-1000111 can be exploited by any local user. For the oldstable distribution (jessie), these problems have been fixed in version 3.16.43-2+deb8u5. For the stable distribution (stretch), these problems have been fixed in version 4.9.30-2+deb9u5. We recommend that you upgrade your linux packages.