In the Linux kernel, the following vulnerability has been resolved: bpf: reject BPF_PSEUDO_FUNC reference to the main program fixups.c:jit_subprogs() rewrites BPF_PSEUDO_FUNC loads to contain real function addresses

Overview

In the Linux kernel, the following vulnerability has been resolved:

bpf: reject BPF_PSEUDO_FUNC reference to the main program

fixups.c:jit_subprogs() rewrites BPF_PSEUDO_FUNC loads to contain real function addresses. This function is invoked from bpf_jit_subprogs() only when env->subprog_cnt > 1. Meaning that for any program like below:

int main(void *ctx) { void *ptr = main; ... bpf_timer_set_callback(..., ptr); ... }

The 'ptr' won't be ever converted to contain an address. In combination with e.g. bpf_timer_set_callback() this would lead to a function call at a bogus address.

Instead of complicating the implementation, just assume that no useful program needs main to be a sync or async callback and reject BPF_PSEUDO_FUNC loads for the main subprogram.

Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.

Vendor advisories

• Red Hat VEX · Moderate · affected: Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 8, Red Hat Enterprise Linux 9, Red Hat OpenShift Container Platform 4 · no fix planned: Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 8, Red Hat Enterprise Linux 9, Red Hat OpenShift Container Platform 4 · updated 2026-10-23 · vex