From: Hao Sun <sunhao.th@xxxxxxxxx> [ Upstream commit cedebd74cf3883f0384af9ec26b4e6f8f1964dd4 ] Verify that nullness information is not porpagated in the branches of register to register JEQ and JNE operations if one of them is PTR_TO_BTF_ID. Implement this in C level so we can use CO-RE. Signed-off-by: Hao Sun <sunhao.th@xxxxxxxxx> Suggested-by: Martin KaFai Lau <martin.lau@xxxxxxxxxx> Link: https://lore.kernel.org/r/20221222024414.29539-2-sunhao.th@xxxxxxxxx Signed-off-by: Martin KaFai Lau <martin.lau@xxxxxxxxxx> Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> --- .../bpf/prog_tests/jeq_infer_not_null.c | 9 ++++ .../bpf/progs/jeq_infer_not_null_fail.c | 42 +++++++++++++++++++ 2 files changed, 51 insertions(+) create mode 100644 tools/testing/selftests/bpf/prog_tests/jeq_infer_not_null.c create mode 100644 tools/testing/selftests/bpf/progs/jeq_infer_not_null_fail.c diff --git a/tools/testing/selftests/bpf/prog_tests/jeq_infer_not_null.c b/tools/testing/selftests/bpf/prog_tests/jeq_infer_not_null.c new file mode 100644 index 000000000000..3add34df5767 --- /dev/null +++ b/tools/testing/selftests/bpf/prog_tests/jeq_infer_not_null.c @@ -0,0 +1,9 @@ +// SPDX-License-Identifier: GPL-2.0 + +#include <test_progs.h> +#include "jeq_infer_not_null_fail.skel.h" + +void test_jeq_infer_not_null(void) +{ + RUN_TESTS(jeq_infer_not_null_fail); +} diff --git a/tools/testing/selftests/bpf/progs/jeq_infer_not_null_fail.c b/tools/testing/selftests/bpf/progs/jeq_infer_not_null_fail.c new file mode 100644 index 000000000000..f46965053acb --- /dev/null +++ b/tools/testing/selftests/bpf/progs/jeq_infer_not_null_fail.c @@ -0,0 +1,42 @@ +// SPDX-License-Identifier: GPL-2.0 + +#include "vmlinux.h" +#include <bpf/bpf_helpers.h> +#include "bpf_misc.h" + +char _license[] SEC("license") = "GPL"; + +struct { + __uint(type, BPF_MAP_TYPE_HASH); + __uint(max_entries, 1); + __type(key, u64); + __type(value, u64); +} m_hash SEC(".maps"); + +SEC("?raw_tp") +__failure __msg("R8 invalid mem access 'map_value_or_null") +int jeq_infer_not_null_ptr_to_btfid(void *ctx) +{ + struct bpf_map *map = (struct bpf_map *)&m_hash; + struct bpf_map *inner_map = map->inner_map_meta; + u64 key = 0, ret = 0, *val; + + val = bpf_map_lookup_elem(map, &key); + /* Do not mark ptr as non-null if one of them is + * PTR_TO_BTF_ID (R9), reject because of invalid + * access to map value (R8). + * + * Here, we need to inline those insns to access + * R8 directly, since compiler may use other reg + * once it figures out val==inner_map. + */ + asm volatile("r8 = %[val];\n" + "r9 = %[inner_map];\n" + "if r8 != r9 goto +1;\n" + "%[ret] = *(u64 *)(r8 +0);\n" + : [ret] "+r"(ret) + : [inner_map] "r"(inner_map), [val] "r"(val) + : "r8", "r9"); + + return ret; +} -- 2.35.1
