(RHSA-2016:1815) Important: kernel security and bug fix update

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

Security Fix(es):

• It was found that the RFC 5961 challenge ACK rate limiting as implemented in the Linux kernel’s networking subsystem allowed an off-path attacker to leak certain information about a given connection by creating congestion on the global challenge ACK rate limit counter and then measuring the changes by probing packets. An off-path attacker could use this flaw to either terminate TCP connection and/or inject payload into non-secured TCP connection between two endpoints on the network. (CVE-2016-5696, Important)

Red Hat would like to thank Yue Cao (Cyber Security Group of the CS department of University of California in Riverside) for reporting this issue.

Bug Fix(es):

• When an interrupt request occurred and the new API was scheduled on a different CPU, the enic driver previously generated a warning message. This behavior was caused by a race condition between the vnic_intr_unmask() function and the enic_poll_unlock_napi() function. This update fixes the napi_poll() function to unlock before unmasking the interrupt. As a result, the warning message no longer occurs in the described situation. (BZ#1351192)