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a=openpgp; fpr=AB9274C96F151C01D3CDB790439744C315ADF86B BPF_MAP_TYPE_ARENA supports direct-value pseudo loads, but unlike array maps its map value_size is zero and the valid direct-value range is the arena mmap size, max_entries * PAGE_SIZE. Commit 3ac1a467e376 ("bpf: Fix off-by-one boundary validation in arena direct-value access") fixed arena_map_direct_value_addr() to reject an offset exactly at the end of the arena mapping. Add a regression test that loads a BPF_PSEUDO_MAP_VALUE with off =3D=3D arena_size and verifies that the verifier rejects it with the expected offset in the log. Unlike __arena global relocation, where insn[1].imm depends on compiler/layout, this raw instruction directly drives map_direct_value_addr(map, &addr, off) with off =3D=3D arena_size, so the boundary check is exercised directly. Assisted-by: ChatGPT:gpt-5.5 Signed-off-by: Woojin Ji --- Tested with a reduced test_progs runner because the local source/output combination has unrelated build failures in progs/bpf_cubic.c and test_kmods/bpf_testmod.ko, so the stock full test_progs binary is not produced. Before fix, on host Arch kernel 7.0.10-arch1-1: arena_direct_value/one_past_end: FAIL, prog_load returned fd 5 After fix, on QEMU guest 7.1.0-rc6-00063-gba3e43a9e601: #1/1 arena_direct_value/one_past_end:OK #1 arena_direct_value:OK Summary: 1/1 PASSED, 0 SKIPPED, 0 FAILED --- .../selftests/bpf/prog_tests/arena_direct_value.c | 73 ++++++++++++++++++= ++++ 1 file changed, 73 insertions(+) diff --git a/tools/testing/selftests/bpf/prog_tests/arena_direct_value.c b/= tools/testing/selftests/bpf/prog_tests/arena_direct_value.c new file mode 100644 index 000000000000..b7760b021670 --- /dev/null +++ b/tools/testing/selftests/bpf/prog_tests/arena_direct_value.c @@ -0,0 +1,73 @@ +// SPDX-License-Identifier: GPL-2.0 + +#include +#include +#include +#include +#include + +#define ARENA_PAGES 32 + +static void test_arena_direct_value_one_past_end(void) +{ + char log_buf[16384] =3D {}, expected[128]; + __u32 arena_sz =3D ARENA_PAGES * getpagesize(); + struct bpf_insn insns[] =3D { + BPF_LD_IMM64_RAW(BPF_REG_1, BPF_PSEUDO_MAP_VALUE, 0), + BPF_MOV64_IMM(BPF_REG_0, 0), + BPF_EXIT_INSN(), + }; + LIBBPF_OPTS(bpf_map_create_opts, map_opts); + LIBBPF_OPTS(bpf_prog_load_opts, prog_opts); + void *arena =3D MAP_FAILED; + int map_fd, prog_fd; + + map_opts.map_flags =3D BPF_F_MMAPABLE; + prog_opts.log_buf =3D log_buf; + prog_opts.log_size =3D sizeof(log_buf); + prog_opts.log_level =3D 1; + + map_fd =3D bpf_map_create(BPF_MAP_TYPE_ARENA, "arena_direct_value", + 0, 0, ARENA_PAGES, &map_opts); + if (map_fd < 0) { + if (errno =3D=3D EOPNOTSUPP || errno =3D=3D EINVAL) { + test__skip(); + return; + } + ASSERT_GE(map_fd, 0, "bpf_map_create"); + return; + } + + arena =3D mmap(NULL, arena_sz, PROT_READ | PROT_WRITE, MAP_SHARED, map_fd= , 0); + if (!ASSERT_NEQ(arena, MAP_FAILED, "arena_mmap")) + goto cleanup; + + insns[0].imm =3D map_fd; + insns[1].imm =3D arena_sz; + + prog_fd =3D bpf_prog_load(BPF_PROG_TYPE_RAW_TRACEPOINT, + "arena_direct_value", "GPL", insns, + ARRAY_SIZE(insns), &prog_opts); + if (!ASSERT_LT(prog_fd, 0, "prog_load")) { + if (prog_fd >=3D 0) + close(prog_fd); + prog_fd =3D -1; + goto cleanup; + } + + snprintf(expected, sizeof(expected), + "invalid access to map value pointer, value_size=3D0 off=3D%u", + arena_sz); + ASSERT_HAS_SUBSTR(log_buf, expected, "verifier_log"); + +cleanup: + if (arena !=3D MAP_FAILED) + munmap(arena, arena_sz); + close(map_fd); +} + +void test_arena_direct_value(void) +{ + if (test__start_subtest("one_past_end")) + test_arena_direct_value_one_past_end(); +} --- base-commit: ba3e43a9e601636f5edb54e259a74f96ca3b8fd8 change-id: 20260603-arena-direct-value-v1-ef4df857b98b Best regards, -- =20 Woojin Ji