Re: [PATCH bpf-next v4 1/4] bpf: Fix an off-by-one error in check_indirect_jump

[Xu Kuohai]

On 1/14/2026 6:29 PM, Anton Protopopov wrote:
> On 26/01/14 05:39PM, Xu Kuohai wrote:
> > From: Xu Kuohai <xukuohai@xxxxxxxxxx>
> >
> > Fix an off-by-one error in check_indirect_jump() that skips the last
> > element returned by copy_insn_array_uniq().
> >
> > Fixes: 493d9e0d6083 ("bpf, x86: add support for indirect jumps")
> > Signed-off-by: Xu Kuohai <xukuohai@xxxxxxxxxx>
> > ---
> >   kernel/bpf/verifier.c | 2 +-
> >   1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
> > index faa1ecc1fe9d..22605d9e0ffa 100644
> > --- a/kernel/bpf/verifier.c
> > +++ b/kernel/bpf/verifier.c
> > @@ -20336,7 +20336,7 @@ static int check_indirect_jump(struct bpf_verifier_env *env, struct bpf_insn *in
> >   		return -EINVAL;
> >   	}
> >   
> > -	for (i = 0; i < n - 1; i++) {
> > +	for (i = 0; i < n; i++) {
> >   		other_branch = push_stack(env, env->gotox_tmp_buf->items[i],
> >   					  env->insn_idx, env->cur_state->speculative);
> >   		if (IS_ERR(other_branch))
> > --
> > 2.47.3
>
> Nack, the last state doesn't require a push_stack() call, it is
> verified directly under this loop. Instead of this patch, just
> add another call to mark_indirect_target().

Ok, I see. Thanks for the explanation.