In the following bpf subprogram:
static int timer_cb(void *map, void *key, void *value)
{
bpf_timer_set_callback(.., timer_cb);
}
the 'timer_cb' is a pointer to a function.
ld_imm64 insn is used to carry this pointer.
bpf_pseudo_func() returns true for such ld_imm64 insn.
Unlike bpf_for_each_map_elem() the bpf_timer_set_callback() is asynchronous.
Relax control flow check to allow such "recursion" that is seen as an infinite
loop by check_cfg(). The distinction between bpf_for_each_map_elem() the
bpf_timer_set_callback() is done in the follow up patch.
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Toke Høiland-Jørgensen <toke@redhat.com>
Link: https://lore.kernel.org/bpf/20210715005417.78572-8-alexei.starovoitov@gmail.com
init_explored_state(env, t + 1);
if (visit_callee) {
init_explored_state(env, t);
- ret = push_insn(t, t + insns[t].imm + 1, BRANCH,
- env, false);
+ ret = push_insn(t, t + insns[t].imm + 1, BRANCH, env,
+ /* It's ok to allow recursion from CFG point of
+ * view. __check_func_call() will do the actual
+ * check.
+ */
+ bpf_pseudo_func(insns + t));
}
return ret;
}