[PATCH v6 mm-new 08/10] selftests/bpf: add test cases for invalid thp_adjust usage

[Yafang Shao <laoar.shao@gmail.com>]

1. The trusted VMA pointer can be null and must be checked before
   dereferencing.
2. Resources acquired via bpf_mm_get_task() must be released with
   bpf_task_release().
3. Memory groups obtained through bpf_mm_get_mem_cgroup() must be released
   using bpf_put_mem_cgroup().

Signed-off-by: Yafang Shao <laoar.shao@gmail.com>
---
 .../selftests/bpf/prog_tests/thp_adjust.c     |  7 +++++
 .../bpf/progs/test_thp_adjust_trusted_vma.c   | 27 +++++++++++++++++++
 .../progs/test_thp_adjust_unreleased_memcg.c  | 24 +++++++++++++++++
 .../progs/test_thp_adjust_unreleased_task.c   | 25 +++++++++++++++++
 4 files changed, 83 insertions(+)
 create mode 100644 tools/testing/selftests/bpf/progs/test_thp_adjust_trusted_vma.c
 create mode 100644 tools/testing/selftests/bpf/progs/test_thp_adjust_unreleased_memcg.c
 create mode 100644 tools/testing/selftests/bpf/progs/test_thp_adjust_unreleased_task.c

diff --git a/tools/testing/selftests/bpf/prog_tests/thp_adjust.c b/tools/testing/selftests/bpf/prog_tests/thp_adjust.c
index 6e65d7b0eb80..846679acaff2 100644
--- a/tools/testing/selftests/bpf/prog_tests/thp_adjust.c
+++ b/tools/testing/selftests/bpf/prog_tests/thp_adjust.c
@@ -11,6 +11,9 @@
 #include <test_progs.h>
 #include "cgroup_helpers.h"
 #include "test_thp_adjust.skel.h"
+#include "test_thp_adjust_trusted_vma.skel.h"
+#include "test_thp_adjust_unreleased_task.skel.h"
+#include "test_thp_adjust_unreleased_memcg.skel.h"
 
 #define LEN (16 * 1024 * 1024) /* 16MB */
 #define THP_ENABLED_FILE "/sys/kernel/mm/transparent_hugepage/enabled"
@@ -333,4 +336,8 @@ void test_thp_adjust(void)
 		subtest_thp_policy_update();
 
 	thp_adjust_destroy();
+
+	RUN_TESTS(test_thp_adjust_trusted_vma);
+	RUN_TESTS(test_thp_adjust_unreleased_task);
+	RUN_TESTS(test_thp_adjust_unreleased_memcg);
 }
diff --git a/tools/testing/selftests/bpf/progs/test_thp_adjust_trusted_vma.c b/tools/testing/selftests/bpf/progs/test_thp_adjust_trusted_vma.c
new file mode 100644
index 000000000000..caa73bebefcf
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/test_thp_adjust_trusted_vma.c
@@ -0,0 +1,27 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include "vmlinux.h"
+#include <bpf/bpf_helpers.h>
+#include <bpf/bpf_tracing.h>
+
+#include "bpf_misc.h"
+
+char _license[] SEC("license") = "GPL";
+
+SEC("struct_ops/get_suggested_order")
+__failure __msg("R1 invalid mem access 'trusted_ptr_or_null_'")
+int BPF_PROG(thp_trusted_vma, struct mm_struct *mm, struct vm_area_struct *vma__nullable,
+	     u64 vma_flags, u64 tva_flags, int orders)
+{
+	struct mem_cgroup *memcg = bpf_mm_get_mem_cgroup(vma__nullable->vm_mm);
+
+	if (!memcg)
+		return 0;
+
+	bpf_put_mem_cgroup(memcg);
+	return 1;
+}
+SEC(".struct_ops.link")
+struct bpf_thp_ops thp_memcg_ops = {
+	.get_suggested_order = (void *)thp_trusted_vma,
+};
diff --git a/tools/testing/selftests/bpf/progs/test_thp_adjust_unreleased_memcg.c b/tools/testing/selftests/bpf/progs/test_thp_adjust_unreleased_memcg.c
new file mode 100644
index 000000000000..467befebb35f
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/test_thp_adjust_unreleased_memcg.c
@@ -0,0 +1,24 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include "vmlinux.h"
+#include <bpf/bpf_helpers.h>
+#include <bpf/bpf_tracing.h>
+
+#include "bpf_misc.h"
+
+char _license[] SEC("license") = "GPL";
+
+SEC("struct_ops/get_suggested_order")
+__failure __msg("Unreleased reference")
+int BPF_PROG(thp_unreleased_memcg, struct mm_struct *mm, struct vm_area_struct *vma__nullable,
+	     u64 vma_flags, u64 tva_flags, int orders)
+{
+	struct mem_cgroup *memcg = bpf_mm_get_mem_cgroup(mm);
+
+	/* The memcg should be released with bpf_put_mem_cgroup() */
+	return memcg ? 0 : 1;
+}
+SEC(".struct_ops.link")
+struct bpf_thp_ops thp_memcg_ops = {
+	.get_suggested_order = (void *)thp_unreleased_memcg,
+};
diff --git a/tools/testing/selftests/bpf/progs/test_thp_adjust_unreleased_task.c b/tools/testing/selftests/bpf/progs/test_thp_adjust_unreleased_task.c
new file mode 100644
index 000000000000..50d756810412
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/test_thp_adjust_unreleased_task.c
@@ -0,0 +1,25 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include "vmlinux.h"
+#include <bpf/bpf_helpers.h>
+#include <bpf/bpf_tracing.h>
+
+#include "bpf_misc.h"
+
+char _license[] SEC("license") = "GPL";
+
+SEC("struct_ops/get_suggested_order")
+__failure __msg("Unreleased reference")
+int BPF_PROG(thp_unreleased_task, struct mm_struct *mm, struct vm_area_struct *vma__nullable,
+	     u64 vma_flags, u64 tva_flags, int orders)
+{
+	struct task_struct *p = bpf_mm_get_task(mm);
+
+	/* The task should be released with bpf_task_release() */
+	return p ? 0 : 1;
+}
+
+SEC(".struct_ops.link")
+struct bpf_thp_ops thp_task_ops = {
+	.get_suggested_order = (void *)thp_unreleased_task,
+};
-- 
2.47.3