Oracle Linux: CVE-2021-3489: ELSA-2021-4356: kernel security, bug fix, and enhancement update (MODERATE) (Multiple Advisories)

The eBPF RINGBUF bpf_ringbuf_reserve() function in the Linux kernel did not check that the allocated size was smaller than the ringbuf size, allowing an attacker to perform out-of-bounds writes within the kernel and therefore, arbitrary code execution. This issue was fixed via commit 4b81ccebaeee ("bpf, ringbuf: Deny reserve of buffers larger than ringbuf") (v5.13-rc4) and backported to the stable kernels in v5.12.4, v5.11.21, and v5.10.37. It was introduced via 457f44363a88 ("bpf: Implement BPF ring buffer and verifier support for it") (v5.8-rc1).
A flaw out of bound memory write in the Linux kernel BPF subsystem was found in the way user writes to BPF ring buffer too fast, so larger buffer than available memory could be allocated. A local user could use this flaw to crash the system or possibly escalate their privileges on the system.