Medium [CVE-2022-1012] Kernel: memory leak problem was found in the TCP source port generation algorithm in net/ipv4/tcp.c due to the small table perturb size

A memory leak problem was found in the TCP source port generation algorithm in net/ipv4/tcp.c due to the small table perturb size. This flaw may allow an attacker to information leak and may cause a denial of service problem.

This flaw allows an attacker to positively distinguish a system among devices with identical hardware and software, which lasts until the device restarts. An attacker can guess the evolution of the internal state used for source port generation.

This information is used to infer the TCP traffic patterns of the victim, guessing the number of outgoing TCP connections established in a specific time frame, which can lead to a system fingerprinting. Red Hat Enterprise Linux version 7 (RHEL7) is not affected by this issue.

While RHEL7 implements the TCP port randomization algorithm 3 (the Simple Hash-Based Port Selection Algorithm), which knowingly has shortcomings (as per RFC 6056, item 3.3.3), the object of study of this flaw was the TCP port selector algorithm 4, the Double-Hash Port Selection Algorithm, which is not existent in RHEL7.

This flaw is ranked as a Moderate impact due to: * Limited exposure of the data in the TCP stack; * The impact of this vulnerability is limited to a system fingerprinting; * The requirements to carry the attack are elevated, requiring monitoring of the data flow.