On Mon, 2023-12-04 at 15:39 -0800, Andrii Nakryiko wrote: [...] > diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c > index 16d5550eda4d..642260d277ce 100644 > --- a/kernel/bpf/verifier.c > +++ b/kernel/bpf/verifier.c > @@ -19899,18 +19899,6 @@ static int do_check_common(struct bpf_verifier_env *env, int subprog) > /* 1st arg to a function */ > regs[BPF_REG_1].type = PTR_TO_CTX; > mark_reg_known_zero(env, regs, BPF_REG_1); > - ret = btf_check_subprog_arg_match(env, subprog, regs); Not sure if this is important or not. btf_check_subprog_arg_match() might have set 'func_info_aux[subprog].unreliable = true'. bpf_check_attach_target() checks this flag for subprograms that are being replaced, and seem to be ok accepting 'subprog == 0'. This change makes it so .unreliable is never set for 'subprog == 0'. [...]
