CVE-2026-98075bpf: reject BPF_PSEUDO_FUNC reference to the main program

Official description

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.

Affected packages & fixed versions

Affected products (as reported)

References

• https://git.kernel.org/stable/c/c74750dca96f40a1adb9d334f5a3152f44b270c3
• https://git.kernel.org/stable/c/314c8caa9cb64ad60c5b969fe9a3e2dcdccf156f
• https://git.kernel.org/stable/c/8cb75f7ada25b1cf25f2f74dec3ba649b9064a09
• https://git.kernel.org/stable/c/118212417ba0120d99f84154799f8880f07411f4
• https://git.kernel.org/stable/c/d6c39774ae093c9f7009cc4ae918f18fc1af7ae7
• https://git.kernel.org/stable/c/92f0bd0e2b632c6565ac2214a4d7d2ed37e5b9f6
• https://git.kernel.org/stable/c/374b2c5561db80fcdd7cdce44af37a49416f61c7