From aada9ce644e53410954daa6beb1f7c4ca158abd7 Mon Sep 17 00:00:00 2001 From: Alexei Starovoitov Date: Mon, 25 Dec 2017 13:15:42 -0800 Subject: [PATCH] bpf: fix max call depth check fix off by one error in max call depth check and add a test Fixes: f4d7e40a5b71 ("bpf: introduce function calls (verification)") Signed-off-by: Alexei Starovoitov Signed-off-by: Daniel Borkmann --- kernel/bpf/verifier.c | 4 ++-- tools/testing/selftests/bpf/test_verifier.c | 35 +++++++++++++++++++++++++++++ 2 files changed, 37 insertions(+), 2 deletions(-) diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index 738e919..52ad60b 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -2126,9 +2126,9 @@ static int check_func_call(struct bpf_verifier_env *env, struct bpf_insn *insn, struct bpf_func_state *caller, *callee; int i, subprog, target_insn; - if (state->curframe >= MAX_CALL_FRAMES) { + if (state->curframe + 1 >= MAX_CALL_FRAMES) { verbose(env, "the call stack of %d frames is too deep\n", - state->curframe); + state->curframe + 2); return -E2BIG; } diff --git a/tools/testing/selftests/bpf/test_verifier.c b/tools/testing/selftests/bpf/test_verifier.c index b5a7a6c..5d0a574 100644 --- a/tools/testing/selftests/bpf/test_verifier.c +++ b/tools/testing/selftests/bpf/test_verifier.c @@ -8885,6 +8885,41 @@ static struct bpf_test tests[] = { .errstr = "combined stack", }, { + "calls: stack depth check using three frames. test5", + .insns = { + /* main */ + BPF_RAW_INSN(BPF_JMP|BPF_CALL, 0, 1, 0, 1), /* call A */ + BPF_EXIT_INSN(), + /* A */ + BPF_RAW_INSN(BPF_JMP|BPF_CALL, 0, 1, 0, 1), /* call B */ + BPF_EXIT_INSN(), + /* B */ + BPF_RAW_INSN(BPF_JMP|BPF_CALL, 0, 1, 0, 1), /* call C */ + BPF_EXIT_INSN(), + /* C */ + BPF_RAW_INSN(BPF_JMP|BPF_CALL, 0, 1, 0, 1), /* call D */ + BPF_EXIT_INSN(), + /* D */ + BPF_RAW_INSN(BPF_JMP|BPF_CALL, 0, 1, 0, 1), /* call E */ + BPF_EXIT_INSN(), + /* E */ + BPF_RAW_INSN(BPF_JMP|BPF_CALL, 0, 1, 0, 1), /* call F */ + BPF_EXIT_INSN(), + /* F */ + BPF_RAW_INSN(BPF_JMP|BPF_CALL, 0, 1, 0, 1), /* call G */ + BPF_EXIT_INSN(), + /* G */ + BPF_RAW_INSN(BPF_JMP|BPF_CALL, 0, 1, 0, 1), /* call H */ + BPF_EXIT_INSN(), + /* H */ + BPF_MOV64_IMM(BPF_REG_0, 0), + BPF_EXIT_INSN(), + }, + .prog_type = BPF_PROG_TYPE_XDP, + .errstr = "call stack", + .result = REJECT, + }, + { "calls: spill into caller stack frame", .insns = { BPF_ST_MEM(BPF_DW, BPF_REG_10, -8, 0), -- 2.7.4