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bpf: Factor out visit_func_call_insn() in check_cfg()

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During verifier check_cfg(), all instructions are
visited to ensure verifier can handle program control flows.
This patch factored out function visit_func_call_insn()
so it can be reused in later patch to visit callback function
calls. There is no functionality change for this patch.

Signed-off-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20210226204920.3884136-1-yhs@fb.com
This commit is contained in:
Yonghong Song 2021-02-26 12:49:20 -08:00 committed by Alexei Starovoitov
parent 86fd166575
commit efdb22de7d
1 changed files with 23 additions and 12 deletions
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35
kernel/bpf/verifier.c
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@ -8592,6 +8592,27 @@ static int push_insn(int t, int w, int e, struct bpf_verifier_env *env,
return DONE_EXPLORING;
}
static int visit_func_call_insn(int t, int insn_cnt,
struct bpf_insn *insns,
struct bpf_verifier_env *env,
bool visit_callee)
{
int ret;
ret = push_insn(t, t + 1, FALLTHROUGH, env, false);
if (ret)
return ret;
if (t + 1 < insn_cnt)
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);
}
return ret;
}
/* Visits the instruction at index t and returns one of the following:
* < 0 - an error occurred
* DONE_EXPLORING - the instruction was fully explored
@ -8612,18 +8633,8 @@ static int visit_insn(int t, int insn_cnt, struct bpf_verifier_env *env)
return DONE_EXPLORING;
case BPF_CALL:
ret = push_insn(t, t + 1, FALLTHROUGH, env, false);
if (ret)
return ret;
if (t + 1 < insn_cnt)
init_explored_state(env, t + 1);
if (insns[t].src_reg == BPF_PSEUDO_CALL) {
init_explored_state(env, t);
ret = push_insn(t, t + insns[t].imm + 1, BRANCH,
env, false);
}
return ret;
return visit_func_call_insn(t, insn_cnt, insns, env,
insns[t].src_reg == BPF_PSEUDO_CALL);
case BPF_JA:
if (BPF_SRC(insns[t].code) != BPF_K)