(RHSA-2016:1657) Important: kernel security update

The kernel packages contain the Linux kernel, the core of any Linux operating system.

Security Fix(es):

• A flaw was found in the Linux kernel’s keyring handling code, where in key_reject_and_link() an uninitialised variable would eventually lead to arbitrary free address which could allow attacker to use a use-after-free style attack. (CVE-2016-4470, Important)

• A flaw was found in the way certain interfaces of the Linux kernel’s Infiniband subsystem used write() as bi-directional ioctl() replacement, which could lead to insufficient memory security checks when being invoked using the splice() system call. A local unprivileged user on a system with either Infiniband hardware present or RDMA Userspace Connection Manager Access module explicitly loaded, could use this flaw to escalate their privileges on the system. (CVE-2016-4565, Important)

• A flaw was found in the implementation of the Linux kernel’s handling of networking challenge ack where an attacker is able to determine the shared counter which could be used to determine sequence numbers for TCP stream injection. (CVE-2016-5696, Important)

Red Hat would like to thank Jann Horn for reporting CVE-2016-4565 and Yue Cao (Cyber Security Group of the CS department of University of California in Riverside) for reporting CVE-2016-5696. The CVE-2016-4470 issue was discovered by David Howells (Red Hat Inc.).