Oracle has issued an update for kernel-uek included in Oracle VM Server for x86 to patch a vulnerability that could cause a DoS.
PUBLISH DATE: 17-09-2018
Linux kernel versions 4.9+ can be forced to make very expensive calls to tcp_collapse_ofo_queue() and tcp_prune_ofo_queue() for every incoming packet which can lead to a denial of service. Oracle has released updates for the vulnerability.
Linux kernel’s handling of specially crafted TCP packets was found to be flawed with an error called SegmentSmack. The flaw can be exploited by a remote attacker by injecting specially modified packets in the out_of_order_queue to induce expensive calls to tcp_collapse_ofo_queue() and tcp_prune_ofo_queue() functions, within ongoing TCP sessions. This could lead to a CPU saturation and hence a denial of service on the system.
Maintaining the denial of service condition requires continuous two-way TCP sessions to a reachable open port, thus the attacks cannot be performed using spoofed IP addresses.
This patch series makes sure we cut cpu cycles enough to render the attack not critical.
Oracle VM Server 3.x
Apply updated packages concerning Oracle VM Server for x86 version 3.4.
Follow vendor’s advisory for further help.