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| author | Edward Cree <ecree@solarflare.com> | 2017-07-21 14:36:57 +0100 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2017-07-24 14:02:55 -0700 |
| commit | 545722cb0fc993226a01844fb27cf832459eb1c0 (patch) | |
| tree | 4797885bb9959ee5a792938e42fa927522bf8719 | |
| parent | 70dba204a396c1c094749c4ef9bd27d5e8176a08 (diff) | |
| download | linux-stable-545722cb0fc993226a01844fb27cf832459eb1c0.tar.gz linux-stable-545722cb0fc993226a01844fb27cf832459eb1c0.tar.bz2 linux-stable-545722cb0fc993226a01844fb27cf832459eb1c0.zip | |
selftests/bpf: subtraction bounds test
There is a bug in the verifier's handling of BPF_SUB: [a,b] - [c,d] yields
was [a-c, b-d] rather than the correct [a-d, b-c]. So here is a test
which, with the bogus handling, will produce ranges of [0,0] and thus
allowed accesses; whereas the correct handling will give a range of
[-255, 255] (and hence the right-shift will give a range of [0, 255]) and
the accesses will be rejected.
Signed-off-by: Edward Cree <ecree@solarflare.com>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
| -rw-r--r-- | tools/testing/selftests/bpf/test_verifier.c | 28 |
1 files changed, 28 insertions, 0 deletions
diff --git a/tools/testing/selftests/bpf/test_verifier.c b/tools/testing/selftests/bpf/test_verifier.c index af7d173910f4..addea82f76c9 100644 --- a/tools/testing/selftests/bpf/test_verifier.c +++ b/tools/testing/selftests/bpf/test_verifier.c @@ -5980,6 +5980,34 @@ static struct bpf_test tests[] = { .result = REJECT, .result_unpriv = REJECT, }, + { + "subtraction bounds (map value)", + .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, 9), + BPF_LDX_MEM(BPF_B, BPF_REG_1, BPF_REG_0, 0), + BPF_JMP_IMM(BPF_JGT, BPF_REG_1, 0xff, 7), + BPF_LDX_MEM(BPF_B, BPF_REG_3, BPF_REG_0, 1), + BPF_JMP_IMM(BPF_JGT, BPF_REG_3, 0xff, 5), + BPF_ALU64_REG(BPF_SUB, BPF_REG_1, BPF_REG_3), + BPF_ALU64_IMM(BPF_RSH, BPF_REG_1, 56), + BPF_ALU64_REG(BPF_ADD, BPF_REG_0, BPF_REG_1), + BPF_LDX_MEM(BPF_B, BPF_REG_0, BPF_REG_0, 0), + BPF_EXIT_INSN(), + BPF_MOV64_IMM(BPF_REG_0, 0), + BPF_EXIT_INSN(), + }, + .fixup_map1 = { 3 }, + .errstr_unpriv = "R0 pointer arithmetic prohibited", + .errstr = "R0 min value is negative, either use unsigned index or do a if (index >=0) check.", + .result = REJECT, + .result_unpriv = REJECT, + }, }; static int probe_filter_length(const struct bpf_insn *fp) |