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bpf: fix max call depth check

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fix off by one error in max call depth check
and add a test

Fixes: f4d7e40a5b ("bpf: introduce function calls (verification)")
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
This commit is contained in:
Alexei Starovoitov 2017-12-25 13:15:42 -08:00 committed by Daniel Borkmann
parent 6b86c4217c
commit aada9ce644
2 changed files with 37 additions and 2 deletions
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4
kernel/bpf/verifier.c
View File

@ -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;
}

35
tools/testing/selftests/bpf/test_verifier.c
View File

@ -8884,6 +8884,41 @@ static struct bpf_test tests[] = {
.result = REJECT,
.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 = {