Medium [CVE-2026-53092] Fix linked reg delta tracking when src_reg == dst_reg

In the Linux kernel, the following vulnerability has been resolved: bpf: Fix linked reg delta tracking when src_reg == dst_reg Consider the case of rX += rX where src_reg and dst_reg are pointers to the same bpf_reg_state in adjust_reg_min_max_vals().

The latter first modifies the dst_reg in-place, and later in the delta tracking, the subsequent is_reg_const(src_reg)/reg_const_value(src_reg) reads the post-{add,sub} value instead of the original source.

This is problematic since it sets an incorrect delta, which sync_linked_regs() then propagates to linked registers, thus creating a verifier-vs-runtime mismatch. Fix it by just skipping this corner case.

A flaw was found in the Linux kernel's Berkeley Packet Filter (BPF) subsystem. This vulnerability occurs due to incorrect delta tracking when source and destination registers are the same during register value adjustments.

This can lead to a mismatch between the BPF verifier's analysis and the actual runtime behavior of BPF programs, potentially allowing a malicious BPF program to bypass security checks. This CVE has been rated as Moderate because eBPF (and XDP) is restricted to root-only on Red Hat Enterprise Linux.

Red Hat severity: Moderate — CVSS 6.4 (CVSS:3.1/AV:L/AC:H/PR:H/UI:N/S:U/C:H/I:H/A:H). Weakness: CWE-393.

Affected Red Hat products: Red Hat Enterprise Linux 10; Red Hat Enterprise Linux 9.