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selftests/bpf: add a test for a pruning bug in the verifier 

The test makes a read through a map value pointer, then considers pruning
 a branch where the register holds an adjusted map value pointer.  It
 should not prune, but currently it does.

Signed-off-by: Alexei Starovoitov <ast@fb.com>
[ecree@solarflare.com: added test-name and patch description]
Signed-off-by: Edward Cree <ecree@solarflare.com>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Alexei Starovoitov 2017-08-23 15:10:26 +01:00 committed by David S. Miller
parent 63f45f8406
commit df20cb7ec1
1 changed files with 28 additions and 0 deletions
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28
tools/testing/selftests/bpf/test_verifier.c
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@ -6503,6 +6503,34 @@ static struct bpf_test tests[] = {
.result = REJECT,
.prog_type = BPF_PROG_TYPE_LWT_IN,
},
{
"varlen_map_value_access pruning",
.insns = {
BPF_ST_MEM(BPF_DW, BPF_REG_10, -8, 0),
BPF_MOV64_REG(BPF_REG_2, BPF_REG_10),
BPF_ALU64_IMM(BPF_ADD, BPF_REG_2, -8),
BPF_LD_MAP_FD(BPF_REG_1, 0),
BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 0, 0,
BPF_FUNC_map_lookup_elem),
BPF_JMP_IMM(BPF_JEQ, BPF_REG_0, 0, 8),
BPF_LDX_MEM(BPF_DW, BPF_REG_1, BPF_REG_0, 0),
BPF_MOV32_IMM(BPF_REG_2, MAX_ENTRIES),
BPF_JMP_REG(BPF_JSGT, BPF_REG_2, BPF_REG_1, 1),
BPF_MOV32_IMM(BPF_REG_1, 0),
BPF_ALU32_IMM(BPF_LSH, BPF_REG_1, 2),
BPF_ALU64_REG(BPF_ADD, BPF_REG_0, BPF_REG_1),
BPF_JMP_IMM(BPF_JA, 0, 0, 0),
BPF_ST_MEM(BPF_DW, BPF_REG_0, 0,
offsetof(struct test_val, foo)),
BPF_EXIT_INSN(),
},
.fixup_map2 = { 3 },
.errstr_unpriv = "R0 leaks addr",
.errstr = "R0 unbounded memory access",
.result_unpriv = REJECT,
.result = REJECT,
.flags = F_NEEDS_EFFICIENT_UNALIGNED_ACCESS,
},
};
static int probe_filter_length(const struct bpf_insn *fp)