RHSA-2017:0931: Important: kernel-rt security and bug fix update

First published: Wed Apr 12 2017(Updated: )

The kernel-rt packages provide the Real Time Linux Kernel, which enables fine-tuning for systems with extremely high determinism requirements.<br>Security Fix(es):<br><li> A race condition flaw was found in the N_HLDC Linux kernel driver when accessing n_hdlc.tbuf list that can lead to double free. A local, unprivileged user able to set the HDLC line discipline on the tty device could use this flaw to increase their privileges on the system. (CVE-2017-2636, Important)</li> <li> A flaw was found in the Linux kernel key management subsystem in which a local attacker could crash the kernel or corrupt the stack and additional memory (denial of service) by supplying a specially crafted RSA key. This flaw panics the machine during the verification of the RSA key. (CVE-2016-8650, Moderate)</li> <li> A flaw was found in the Linux kernel's implementation of setsockopt for the SO_{SND|RCV}BUFFORCE setsockopt() system call. Users with non-namespace CAP_NET_ADMIN are able to trigger this call and create a situation in which the sockets sendbuff data size could be negative. This could adversely affect memory allocations and create situations where the system could crash or cause memory corruption. (CVE-2016-9793, Moderate)</li> <li> A flaw was found in the Linux kernel's handling of clearing SELinux attributes on /proc/pid/attr files. An empty (null) write to this file can crash the system by causing the system to attempt to access unmapped kernel memory. (CVE-2017-2618, Moderate)</li> Red Hat would like to thank Alexander Popov for reporting CVE-2017-2636 and Ralf Spenneberg for reporting CVE-2016-8650. The CVE-2017-2618 issue was discovered by Paul Moore (Red Hat Engineering).<br>Bug Fix(es):<br><li> Previously, a cgroups data structure was sometimes corrupted due to a race condition in the kernel-rt cgroups code. Consequently, several system tasks were blocked, and the operating system became unresponsive. This update adds a lock that prevents the race condition. As a result, the cgroups data structure no longer gets corrupted and the operating system no longer hangs under the described circumstances. (BZ#1420784)</li> <li> The kernel-rt packages have been upgraded to the 3.10.0-514.16.1 source tree, which provides a number of bug fixes over the previous version. (BZ#1430749)</li>

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