New Linux kernel security updates have been released for Ubuntu 17.10 (Artful Aardvark), Ubuntu 16.04 LTS (Xenial Xerus), Ubuntu 14.04 LTS (Trusty Tahr), and Ubuntu 12.04 ESM (Extended Security Maintenance), adding the compiler-based retpoline kernel mitigation for the Spectre Variant 2 vulnerability on amd64 and i386 architectures.
Canonical fixed the Spectre Variant 2 security vulnerability last month on January 22, but only for 64-bit Ubuntu installations. This update apparently mitigates the issue for 32-bit installations too. Spectre is a nasty hardware bug in microprocessors that use branch prediction and speculative execution and it could allow unauthorized memory reads via side-channel attacks.
In addition to this, the new kernel updates address a race condition (CVE-2017-17712) in Linux kernel’s IPv4 raw socket implementation and a use-after-free vulnerability (CVE-2017-8824) in the DCCP protocol implementation, allowing a local attacker to execute arbitrary code or cause a denial of service. Both security flaws were discovered by Mohamed Ghannam.
Also, the new kernel patches a use-after-free vulnerability (CVE-2017-15115) discovered by ChunYu Wang in Linux kernel’s SCTP protocol implementation, which could allow a local attacker to crash the system by causing a denial of service or execute arbitrary code. These security issues affect Ubuntu 17.10, Ubuntu 16.04 LTS, and Ubuntu 14.04 LTS.
Submitted by: Arnfried Walbrecht