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| author |   Edward Cree <ecree@solarflare.com> | 2017-08-07 15:29:51 +0100 |
|---|---|---|
| committer |   David S. Miller <davem@davemloft.net> | 2017-08-08 17:51:35 -0700 |
| commit | 69c4e8ada616ce5ad4e37d6acca851d648dbdfa9 (patch) | |
| tree | 67cea8f40e147278ce13b4804474b7b22e42d651 /tools | |
| parent | selftests/bpf: add tests for subtraction & negative numbers (diff) | |
| download | linux-dev-69c4e8ada616ce5ad4e37d6acca851d648dbdfa9.tar.xz linux-dev-69c4e8ada616ce5ad4e37d6acca851d648dbdfa9.zip | |
selftests/bpf: variable offset negative tests
Variable ctx accesses and stack accesses aren't allowed, because we can't
determine what type of value will be read.
Signed-off-by: Edward Cree <ecree@solarflare.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'tools')
| -rw-r--r-- | tools/testing/selftests/bpf/test_verifier.c | 41 |
1 files changed, 41 insertions, 0 deletions
diff --git a/tools/testing/selftests/bpf/test_verifier.c b/tools/testing/selftests/bpf/test_verifier.c index 876b8785fd83..65aa562cff87 100644 --- a/tools/testing/selftests/bpf/test_verifier.c +++ b/tools/testing/selftests/bpf/test_verifier.c @@ -5980,6 +5980,47 @@ static struct bpf_test tests[] = { .errstr = "R0 min value is negative, either use unsigned index or do a if (index >=0) check.", .result = REJECT, }, + { + "variable-offset ctx access", + .insns = { + /* Get an unknown value */ + BPF_LDX_MEM(BPF_W, BPF_REG_2, BPF_REG_1, 0), + /* Make it small and 4-byte aligned */ + BPF_ALU64_IMM(BPF_AND, BPF_REG_2, 4), + /* add it to skb. We now have either &skb->len or + * &skb->pkt_type, but we don't know which + */ + BPF_ALU64_REG(BPF_ADD, BPF_REG_1, BPF_REG_2), + /* dereference it */ + BPF_LDX_MEM(BPF_W, BPF_REG_0, BPF_REG_1, 0), + BPF_EXIT_INSN(), + }, + .errstr = "variable ctx access var_off=(0x0; 0x4)", + .result = REJECT, + .prog_type = BPF_PROG_TYPE_LWT_IN, + }, + { + "variable-offset stack access", + .insns = { + /* Fill the top 8 bytes of the stack */ + BPF_ST_MEM(BPF_DW, BPF_REG_10, -8, 0), + /* Get an unknown value */ + BPF_LDX_MEM(BPF_W, BPF_REG_2, BPF_REG_1, 0), + /* Make it small and 4-byte aligned */ + BPF_ALU64_IMM(BPF_AND, BPF_REG_2, 4), + BPF_ALU64_IMM(BPF_SUB, BPF_REG_2, 8), + /* add it to fp. We now have either fp-4 or fp-8, but + * we don't know which + */ + BPF_ALU64_REG(BPF_ADD, BPF_REG_2, BPF_REG_10), + /* dereference it */ + BPF_LDX_MEM(BPF_W, BPF_REG_0, BPF_REG_2, 0), + BPF_EXIT_INSN(), + }, + .errstr = "variable stack access var_off=(0xfffffffffffffff8; 0x4)", + .result = REJECT, + .prog_type = BPF_PROG_TYPE_LWT_IN, + }, }; static int probe_filter_length(const struct bpf_insn *fp) |