MGASA-2018-0127

This kernel-linus update is based on the upstream 4.14.18 and and adds some support for mitigating Spectre, variant 1 (CVE-2017-5753) and as it is built with the retpoline-aware gcc-5.5.0-1.mga6, it now provides full retpoline mitigation for Spectre, variant 2 (CVE-2017-5715).

The BPF interpreter has been used as part of the spectre 2 attack CVE-2017-5715. To make attacker job harder introduce BPFJITALWAYS_ON config option that removes interpreter from the kernel in favor of JIT-only mode. This is now enabled by default in Mageia kernels.

Other security fixes in this update:

Linux kernel version 3.3-rc1 and later is affected by a vulnerability lies in the processing of incoming L2CAP commands - ConfigRequest, and ConfigResponse messages. This info leak is a result of uninitialized stack variables that may be returned to an attacker in their uninitialized state. By manipulating the code flows that precede the handling of these configuration messages, an attacker can also gain some control over which data will be held in the uninitialized stack variables. This can allow him to bypass KASLR, and stack canaries protection - as both pointers and stack canaries may be leaked in this manner (CVE-2017-1000410).

A use-after-free vulnerability was found in network namespaces code affecting the Linux kernel before 4.14.11. The function getnetnsbyid() in net/core/netnamespace.c does not check for the net::count value after it has found a peer network in netnsids idr, which could lead to double free and memory corruption. This vulnerability could allow an unprivileged local user to induce kernel memory corruption on the system, leading to a crash. Due to the nature of the flaw, privilege escalation cannot be fully ruled out, although it is thought to be unlikely (CVE-2017-15129).

The KVM implementation in the Linux kernel through 4.14.7 allows attackers to obtain potentially sensitive information from kernel memory, aka a write_mmio stack-based out-of-bounds read, related to arch/x86/kvm/x86.c and include/trace/events/kvm.h (CVE-2017-17741).

For other fixes in this update, read the referenced changelogs.