7.6 - DSA-3791

Several vulnerabilities have been discovered in the Linux kernel that may lead to a privilege escalation, denial of service or have other impacts.

CVE-2016-6786 / CVE-2016-6787

It was discovered that the performance events subsystem does not properly manage locks during certain migrations, allowing a local attacker to escalate privileges. This can be mitigated by disabling unprivileged use of performance events: sysctl kernel.perf_event_paranoid=3

CVE-2016-8405

Peter Pi of Trend Micro discovered that the frame buffer video subsystem does not properly check bounds while copying color maps to userspace, causing a heap buffer out-of-bounds read, leading to information disclosure.

CVE-2016-9191

CAI Qian discovered that reference counting is not properly handled within proc_sys_readdir in the sysctl implementation, allowing a local denial of service (system hang) or possibly privilege escalation.

CVE-2017-2583

Xiaohan Zhang reported that KVM for amd64 does not correctly emulate loading of a null stack selector. This can be used by a user in a guest VM for denial of service (on an Intel CPU) or to escalate privileges within the VM (on an AMD CPU).

CVE-2017-2584

Dmitry Vyukov reported that KVM for x86 does not correctly emulate memory access by the SGDT and SIDT instructions, which can result in a use-after-free and information leak.

CVE-2017-2596

Dmitry Vyukov reported that KVM leaks page references when emulating a VMON for a nested hypervisor. This can be used by a privileged user in a guest VM for denial of service or possibly to gain privileges in the host.

CVE-2017-2618

It was discovered that an off-by-one in the handling of SELinux attributes in /proc/pid/attr could result in local denial of service.

CVE-2017-5549

It was discovered that the KLSI KL5KUSB105 serial USB device driver could log the contents of uninitialised kernel memory, resulting in an information leak.

CVE-2017-5551

Jan Kara found that changing the POSIX ACL of a file on tmpfs never cleared its set-group-ID flag, which should be done if the user changing it is not a member of the group-owner. In some cases, this would allow the user-owner of an executable to gain the privileges of the group-owner.

CVE-2017-5897

Andrey Konovalov discovered an out-of-bounds read flaw in the ip6gre_err function in the IPv6 networking code.

CVE-2017-5970

Andrey Konovalov discovered a denial-of-service flaw in the IPv4 networking code. This can be triggered by a local or remote attacker if a local UDP or raw socket has the IP_RETOPTS option enabled.

CVE-2017-6001

Di Shen discovered a race condition between concurrent calls to the performance events subsystem, allowing a local attacker to escalate privileges. This flaw exists because of an incomplete fix of CVE-2016-6786. This can be mitigated by disabling unprivileged use of performance events: sysctl kernel.perf_event_paranoid=3

CVE-2017-6074

Andrey Konovalov discovered a use-after-free vulnerability in the DCCP networking code, which could result in denial of service or local privilege escalation. On systems that do not already have the dccp module loaded, this can be mitigated by disabling it: echo >> /etc/modprobe.d/disable-dccp.conf install dccp false

For the stable distribution (jessie), these problems have been fixed in version 3.16.39-1+deb8u1.

We recommend that you upgrade your linux packages.