Add a test that the verifier rejects kfunc calls where a stack argument exceeds 8 bytes (the register-sized slot limit). Signed-off-by: Yonghong Song --- .../selftests/bpf/prog_tests/stack_arg_fail.c | 24 ++++++++++++++ .../selftests/bpf/progs/stack_arg_fail.c | 32 +++++++++++++++++++ .../selftests/bpf/test_kmods/bpf_testmod.c | 7 ++++ .../bpf/test_kmods/bpf_testmod_kfunc.h | 7 ++++ 4 files changed, 70 insertions(+) create mode 100644 tools/testing/selftests/bpf/prog_tests/stack_arg_fail.c create mode 100644 tools/testing/selftests/bpf/progs/stack_arg_fail.c diff --git a/tools/testing/selftests/bpf/prog_tests/stack_arg_fail.c b/tools/testing/selftests/bpf/prog_tests/stack_arg_fail.c new file mode 100644 index 000000000000..328a79edee45 --- /dev/null +++ b/tools/testing/selftests/bpf/prog_tests/stack_arg_fail.c @@ -0,0 +1,24 @@ +// SPDX-License-Identifier: GPL-2.0 +/* Copyright (c) 2026 Meta Platforms, Inc. and affiliates. */ + +#include +#include "stack_arg_fail.skel.h" + +void test_stack_arg_fail(void) +{ + struct stack_arg_fail *skel; + + skel = stack_arg_fail__open(); + if (!ASSERT_OK_PTR(skel, "open")) + return; + + if (!skel->rodata->has_stack_arg) { + test__skip(); + goto out; + } + + ASSERT_ERR(stack_arg_fail__load(skel), "load_should_fail"); + +out: + stack_arg_fail__destroy(skel); +} diff --git a/tools/testing/selftests/bpf/progs/stack_arg_fail.c b/tools/testing/selftests/bpf/progs/stack_arg_fail.c new file mode 100644 index 000000000000..caa63b6f6a80 --- /dev/null +++ b/tools/testing/selftests/bpf/progs/stack_arg_fail.c @@ -0,0 +1,32 @@ +// SPDX-License-Identifier: GPL-2.0 +/* Copyright (c) 2026 Meta Platforms, Inc. and affiliates. */ + +#include +#include +#include "../test_kmods/bpf_testmod_kfunc.h" + +#if defined(__BPF_FEATURE_STACK_ARGUMENT) + +const volatile bool has_stack_arg = true; + +SEC("tc") +int test_stack_arg_big(struct __sk_buff *skb) +{ + struct prog_test_big_arg s = { .a = 1, .b = 2 }; + + return bpf_kfunc_call_stack_arg_big(1, 2, 3, 4, 5, s); +} + +#else + +const volatile bool has_stack_arg = false; + +SEC("tc") +int test_stack_arg_big(struct __sk_buff *skb) +{ + return 0; +} + +#endif + +char _license[] SEC("license") = "GPL"; diff --git a/tools/testing/selftests/bpf/test_kmods/bpf_testmod.c b/tools/testing/selftests/bpf/test_kmods/bpf_testmod.c index d88ab1dc5106..00d0b238219d 100644 --- a/tools/testing/selftests/bpf/test_kmods/bpf_testmod.c +++ b/tools/testing/selftests/bpf/test_kmods/bpf_testmod.c @@ -843,6 +843,12 @@ __bpf_kfunc u64 bpf_kfunc_call_stack_arg_mix(u64 a, u64 b, u64 c, u64 d, u64 e, return a + b + c + d + e + p->x0 + f + q->x1; } +__bpf_kfunc u64 bpf_kfunc_call_stack_arg_big(u64 a, u64 b, u64 c, u64 d, u64 e, + struct prog_test_big_arg s) +{ + return a + b + c + d + e + s.a + s.b; +} + static struct prog_test_ref_kfunc prog_test_struct = { .a = 42, .b = 108, @@ -1309,6 +1315,7 @@ BTF_ID_FLAGS(func, bpf_kfunc_call_test5) BTF_ID_FLAGS(func, bpf_kfunc_call_stack_arg) BTF_ID_FLAGS(func, bpf_kfunc_call_stack_arg_ptr) BTF_ID_FLAGS(func, bpf_kfunc_call_stack_arg_mix) +BTF_ID_FLAGS(func, bpf_kfunc_call_stack_arg_big) BTF_ID_FLAGS(func, bpf_kfunc_call_test_mem_len_pass1) BTF_ID_FLAGS(func, bpf_kfunc_call_test_mem_len_fail1) BTF_ID_FLAGS(func, bpf_kfunc_call_test_mem_len_fail2) diff --git a/tools/testing/selftests/bpf/test_kmods/bpf_testmod_kfunc.h b/tools/testing/selftests/bpf/test_kmods/bpf_testmod_kfunc.h index f93cf2db12b2..b142b87e9f60 100644 --- a/tools/testing/selftests/bpf/test_kmods/bpf_testmod_kfunc.h +++ b/tools/testing/selftests/bpf/test_kmods/bpf_testmod_kfunc.h @@ -48,6 +48,11 @@ struct prog_test_pass2 { } x; }; +struct prog_test_big_arg { + long a; + long b; +}; + struct prog_test_fail1 { void *p; int x; @@ -118,6 +123,8 @@ __u64 bpf_kfunc_call_stack_arg_ptr(__u64 a, __u64 b, __u64 c, __u64 d, __u64 e, __u64 bpf_kfunc_call_stack_arg_mix(__u64 a, __u64 b, __u64 c, __u64 d, __u64 e, struct prog_test_pass1 *p, __u64 f, struct prog_test_pass1 *q) __ksym; +__u64 bpf_kfunc_call_stack_arg_big(__u64 a, __u64 b, __u64 c, __u64 d, __u64 e, + struct prog_test_big_arg s) __ksym; void bpf_kfunc_call_test_pass_ctx(struct __sk_buff *skb) __ksym; void bpf_kfunc_call_test_pass1(struct prog_test_pass1 *p) __ksym; -- 2.52.0