[PATCH bpf-next v3 2/2] selftests/bpf: Add trampolines multi-level pointer params test coverage

[Slava Imameev]

Multi-level pointer params and return value test coverage for BPF
trampolines:
- fentry/fexit programs covering struct and void double/triple
  pointer parameters and returned values
- verifier context tests covering multi-level pointers as parameters
- verifier context tests covering multi-level pointers as returned
  values
- verifier context tests for lsm to check trusted parameters handling
- verifier context tests covering out-of-bound access after cast
- verifier BPF helper tests to validate no change in verifier
  behaviour

Signed-off-by: Slava Imameev <slava.imameev@xxxxxxxxxxxxxxx>
---
 net/bpf/test_run.c                            | 130 ++++++
 .../prog_tests/fentry_fexit_multi_level_ptr.c | 206 +++++++++
 .../selftests/bpf/prog_tests/verifier.c       |   2 +
 .../progs/fentry_fexit_pptr_nullable_test.c   |  56 +++
 .../bpf/progs/fentry_fexit_pptr_test.c        |  67 +++
 .../bpf/progs/fentry_fexit_void_ppptr_test.c  |  38 ++
 .../bpf/progs/fentry_fexit_void_pptr_test.c   |  71 +++
 .../bpf/progs/verifier_ctx_multilevel_ptr.c   | 435 ++++++++++++++++++
 8 files changed, 1005 insertions(+)
 create mode 100644 tools/testing/selftests/bpf/prog_tests/fentry_fexit_multi_level_ptr.c
 create mode 100644 tools/testing/selftests/bpf/progs/fentry_fexit_pptr_nullable_test.c
 create mode 100644 tools/testing/selftests/bpf/progs/fentry_fexit_pptr_test.c
 create mode 100644 tools/testing/selftests/bpf/progs/fentry_fexit_void_ppptr_test.c
 create mode 100644 tools/testing/selftests/bpf/progs/fentry_fexit_void_pptr_test.c
 create mode 100644 tools/testing/selftests/bpf/progs/verifier_ctx_multilevel_ptr.c

diff --git a/net/bpf/test_run.c b/net/bpf/test_run.c
index 178c4738e63b..9f6ee2eb01cd 100644
--- a/net/bpf/test_run.c
+++ b/net/bpf/test_run.c
@@ -24,6 +24,9 @@
 #include <net/netdev_rx_queue.h>
 #include <net/xdp.h>
 #include <net/netfilter/nf_bpf_link.h>
+#include <linux/set_memory.h>
+#include <linux/string.h>
+#include <asm/tlbflush.h>
 
 #define CREATE_TRACE_POINTS
 #include <trace/events/bpf_test_run.h>
@@ -563,6 +566,42 @@ noinline int bpf_fentry_test10(const void *a)
 	return (long)a;
 }
 
+struct bpf_fentry_test_pptr_t {
+	u32 value1;
+	u32 value2;
+};
+
+noinline int bpf_fentry_test11_pptr_nullable(struct bpf_fentry_test_pptr_t **pptr__nullable)
+{
+	if (!pptr__nullable)
+		return -1;
+
+	return (*pptr__nullable)->value1;
+}
+
+noinline u32 **bpf_fentry_test12_pptr(u32 id, u32 **pptr)
+{
+	/* prevent DCE */
+	asm volatile("" : "+r"(id));
+	asm volatile("" : "+r"(pptr));
+	return pptr;
+}
+
+noinline u8 bpf_fentry_test13_pptr(void **pptr)
+{
+	void *ptr;
+
+	return copy_from_kernel_nofault(&ptr, pptr, sizeof(pptr)) == 0;
+}
+
+/* Test the verifier can handle multi-level pointer types with qualifiers. */
+noinline void ***bpf_fentry_test14_ppptr(void **volatile *const ppptr)
+{
+	/* prevent DCE */
+	asm volatile("" :: "r"(ppptr) : "memory");
+	return (void ***)ppptr;
+}
+
 noinline void bpf_fentry_test_sinfo(struct skb_shared_info *sinfo)
 {
 }
@@ -670,20 +709,110 @@ static void *bpf_test_init(const union bpf_attr *kattr, u32 user_size,
 	return data;
 }
 
+static void *create_bad_kaddr(void)
+{
+	/*
+	 * Try to get an address that passes kernel range checks but causes
+	 * a page fault handler invocation if accessed from a BPF program.
+	 */
+#if defined(CONFIG_ARCH_HAS_SET_MEMORY) && defined(CONFIG_X86)
+	void *addr = vmalloc(PAGE_SIZE);
+
+	if (!addr)
+		return NULL;
+	/* Make it non-present - any access will fault */
+	if (set_memory_np((unsigned long)addr, 1)) {
+		vfree(addr);
+		return NULL;
+	}
+	return addr;
+#elif defined(CONFIG_ARCH_HAS_SET_DIRECT_MAP)
+	struct page *page = alloc_page(GFP_KERNEL);
+
+	if (!page)
+		return NULL;
+	/* Remove from direct map - any access will fault */
+	if (set_direct_map_invalid_noflush(page)) {
+		__free_page(page);
+		return NULL;
+	}
+	flush_tlb_kernel_range((unsigned long)page_address(page),
+			       (unsigned long)page_address(page) + PAGE_SIZE);
+	return page_address(page);
+#endif
+	return NULL;
+}
+
+static void free_bad_kaddr(void *addr)
+{
+	if (!addr)
+		return;
+
+	/*
+	 * Free an invalid test address created by create_bad_kaddr().
+	 * Restores the page to present state before freeing.
+	 */
+#if defined(CONFIG_ARCH_HAS_SET_MEMORY) && defined(CONFIG_X86)
+	set_memory_p((unsigned long)addr, 1);
+	vfree(addr);
+#elif defined(CONFIG_ARCH_HAS_SET_DIRECT_MAP)
+	struct page *page = virt_to_page(addr);
+
+	set_direct_map_default_noflush(page);
+	flush_tlb_kernel_range((unsigned long)addr,
+			       (unsigned long)addr + PAGE_SIZE);
+	__free_page(page);
+#endif
+}
+
+#define CONSUME(val) do { \
+	typeof(val) __var = (val); \
+	__asm__ __volatile__("" : "+r" (__var)); \
+	(void)__var; \
+} while (0)
+
 int bpf_prog_test_run_tracing(struct bpf_prog *prog,
 			      const union bpf_attr *kattr,
 			      union bpf_attr __user *uattr)
 {
 	struct bpf_fentry_test_t arg = {};
+	struct bpf_fentry_test_pptr_t ts = { .value1 = 1979, .value2 = 2026 };
+	struct bpf_fentry_test_pptr_t *ptr = &ts;
+	void *kaddr = NULL;
+	u32 *u32_ptr = (u32 *)29;
 	u16 side_effect = 0, ret = 0;
 	int b = 2, err = -EFAULT;
 	u32 retval = 0;
+	const char *attach_name;
 
 	if (kattr->test.flags || kattr->test.cpu || kattr->test.batch_size)
 		return -EINVAL;
 
+	attach_name = prog->aux->attach_func_name;
+	if (!attach_name)
+		attach_name = "!";
+
 	switch (prog->expected_attach_type) {
 	case BPF_TRACE_FENTRY:
+		if (!strcmp(attach_name, "bpf_fentry_test11_pptr_nullable")) {
+			CONSUME(bpf_fentry_test11_pptr_nullable(&ptr));
+			break;
+		} else if (!strcmp(attach_name, "bpf_fentry_test12_pptr")) {
+			CONSUME(bpf_fentry_test12_pptr(0, &u32_ptr));
+			CONSUME(bpf_fentry_test12_pptr(1, (u32 **)17));
+			break;
+		} else if (!strcmp(attach_name, "bpf_fentry_test13_pptr")) {
+			/* If kaddr is NULL, the test handles this gracefully. */
+			kaddr = create_bad_kaddr();
+			CONSUME(bpf_fentry_test13_pptr(kaddr));
+			CONSUME(bpf_fentry_test13_pptr((void **)19));
+			CONSUME(bpf_fentry_test13_pptr(ERR_PTR(-ENOMEM)));
+			break;
+		} else if (!strcmp(attach_name, "bpf_fentry_test14_ppptr")) {
+			CONSUME(bpf_fentry_test14_ppptr(ERR_PTR(-ENOMEM)));
+			break;
+		}
+		fallthrough;
 	case BPF_TRACE_FEXIT:
 	case BPF_TRACE_FSESSION:
 		if (bpf_fentry_test1(1) != 2 ||
@@ -717,6 +846,7 @@ int bpf_prog_test_run_tracing(struct bpf_prog *prog,
 
 	err = 0;
 out:
+	free_bad_kaddr(kaddr);
 	trace_bpf_test_finish(&err);
 	return err;
 }
diff --git a/tools/testing/selftests/bpf/prog_tests/fentry_fexit_multi_level_ptr.c b/tools/testing/selftests/bpf/prog_tests/fentry_fexit_multi_level_ptr.c
new file mode 100644
index 000000000000..54a4d2720ba4
--- /dev/null
+++ b/tools/testing/selftests/bpf/prog_tests/fentry_fexit_multi_level_ptr.c
@@ -0,0 +1,206 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (c) 2026 CrowdStrike, Inc. */
+#include <test_progs.h>
+#include "fentry_fexit_pptr_nullable_test.skel.h"
+#include "fentry_fexit_pptr_test.skel.h"
+#include "fentry_fexit_void_pptr_test.skel.h"
+#include "fentry_fexit_void_ppptr_test.skel.h"
+
+static void test_fentry_fexit_pptr_nullable(void)
+{
+	struct fentry_fexit_pptr_nullable_test *skel = NULL;
+	int err, prog_fd;
+	LIBBPF_OPTS(bpf_test_run_opts, topts);
+
+	skel = fentry_fexit_pptr_nullable_test__open_and_load();
+	if (!ASSERT_OK_PTR(skel, "fentry_fexit_pptr_nullable_test__open_and_load"))
+		return;
+
+	err = fentry_fexit_pptr_nullable_test__attach(skel);
+	if (!ASSERT_OK(err, "fentry_fexit_pptr_nullable_test__attach"))
+		goto cleanup;
+
+	/* Trigger fentry/fexit programs. */
+	prog_fd = bpf_program__fd(skel->progs.test_fentry_pptr_nullable);
+	err = bpf_prog_test_run_opts(prog_fd, &topts);
+	ASSERT_OK(err, "test_run");
+	ASSERT_EQ(topts.retval, 0, "test_run retval");
+
+	/* Verify fentry was called and captured the correct value. */
+	ASSERT_EQ(skel->bss->fentry_called, 1, "fentry_called");
+	ASSERT_EQ(skel->bss->fentry_ptr_field_value1, 1979, "fentry_ptr_field_value1");
+	ASSERT_EQ(skel->bss->fentry_ptr_field_value2, 2026, "fentry_ptr_field_value2");
+
+	/* Verify fexit captured correct values and return code. */
+	ASSERT_EQ(skel->bss->fexit_called, 1, "fexit_called");
+	ASSERT_EQ(skel->bss->fexit_ptr_field_value1, 1979, "fexit_ptr_field_value1");
+	ASSERT_EQ(skel->bss->fexit_ptr_field_value2, 2026, "fexit_ptr_field_value2");
+	ASSERT_EQ(skel->bss->fexit_retval, 1979, "fexit_retval");
+
+cleanup:
+	fentry_fexit_pptr_nullable_test__destroy(skel);
+}
+
+static void test_fentry_fexit_pptr(void)
+{
+	struct fentry_fexit_pptr_test *skel = NULL;
+	int err, prog_fd, i;
+	LIBBPF_OPTS(bpf_test_run_opts, topts);
+
+	skel = fentry_fexit_pptr_test__open_and_load();
+	if (!ASSERT_OK_PTR(skel, "fentry_fexit_pptr_test__open_and_load"))
+		return;
+
+	/* Poison some values which should be modified by BPF programs. */
+	for (i = 0; i < ARRAY_SIZE(skel->bss->telemetry); ++i) {
+		skel->bss->telemetry[i].id = 30;
+		skel->bss->telemetry[i].fentry_pptr = 31;
+		skel->bss->telemetry[i].fentry_ptr = 32;
+		skel->bss->telemetry[i].fexit_pptr = 33;
+		skel->bss->telemetry[i].fexit_ptr = 34;
+		skel->bss->telemetry[i].fexit_ret_pptr = 35;
+		skel->bss->telemetry[i].fexit_ret_ptr = 36;
+	}
+
+	err = fentry_fexit_pptr_test__attach(skel);
+	if (!ASSERT_OK(err, "fentry_fexit_pptr_test__attach"))
+		goto cleanup;
+
+	/* Trigger fentry/fexit programs */
+	prog_fd = bpf_program__fd(skel->progs.test_fentry_pptr);
+	err = bpf_prog_test_run_opts(prog_fd, &topts);
+	ASSERT_OK(err, "test_run");
+	ASSERT_EQ(topts.retval, 0, "test_run retval");
+
+	for (i = 0; i < ARRAY_SIZE(skel->bss->telemetry); ++i) {
+		ASSERT_TRUE(skel->bss->telemetry[i].id == 0 ||
+			skel->bss->telemetry[i].id == 1, "id");
+		if (skel->bss->telemetry[i].id == 0) {
+			/* Verify fentry captured the correct value. */
+			ASSERT_EQ(skel->bss->telemetry[i].fentry_called, 1, "fentry_called");
+			ASSERT_EQ(skel->bss->telemetry[i].fentry_ptr, (u64)29, "fentry_ptr");
+
+			/* Verify fexit captured correct values and return address. */
+			ASSERT_EQ(skel->bss->telemetry[i].fexit_called, 1, "fexit_called");
+			ASSERT_EQ(skel->bss->telemetry[i].fexit_pptr,
+				skel->bss->telemetry[i].fentry_pptr, "fexit_pptr");
+			ASSERT_EQ(skel->bss->telemetry[i].fexit_ptr, (u64)29, "fexit_ptr");
+			ASSERT_EQ(skel->bss->telemetry[i].fexit_ret_pptr,
+				skel->bss->telemetry[i].fentry_pptr, "fexit_ret_pptr");
+			ASSERT_EQ(skel->bss->telemetry[i].fexit_ret_ptr, (u64)29, "fexit_ret_ptr");
+		} else if (skel->bss->telemetry[i].id == 1) {
+			/* Verify fentry captured the correct value */
+			ASSERT_EQ(skel->bss->telemetry[i].fentry_called, 1, "fentry_called");
+			ASSERT_EQ(skel->bss->telemetry[i].fentry_pptr, 17, "fentry_pptr");
+
+			/*
+			 * Verify fexit captured correct values and return address,
+			 * fentry_ptr value depends on kernel address space layout
+			 * and a mapped page presence at NULL.
+			 */
+			ASSERT_EQ(skel->bss->telemetry[i].fexit_called, 1, "fexit_called");
+			ASSERT_EQ(skel->bss->telemetry[i].fexit_pptr, 17, "fexit_pptr");
+			ASSERT_EQ(skel->bss->telemetry[i].fexit_ptr,
+				skel->bss->telemetry[i].fentry_ptr, "fexit_ptr");
+			ASSERT_EQ(skel->bss->telemetry[i].fexit_ret_pptr, 17, "fexit_ret_pptr");
+			ASSERT_EQ(skel->bss->telemetry[i].fexit_ret_ptr,
+				skel->bss->telemetry[i].fentry_ptr, "fexit_ret_ptr");
+		}
+	}
+
+cleanup:
+	fentry_fexit_pptr_test__destroy(skel);
+}
+
+static void test_fentry_fexit_void_pptr(void)
+{
+	struct fentry_fexit_void_pptr_test *skel = NULL;
+	int err, prog_fd, i;
+	LIBBPF_OPTS(bpf_test_run_opts, topts);
+
+	skel = fentry_fexit_void_pptr_test__open_and_load();
+	if (!ASSERT_OK_PTR(skel, "fentry_fexit_void_pptr_test__open_and_load"))
+		return;
+
+	/* Poison some values which should be modified by BPF programs. */
+	for (i = 0; i < ARRAY_SIZE(skel->bss->telemetry); ++i) {
+		skel->bss->telemetry[i].fentry_pptr = 30;
+		skel->bss->telemetry[i].fentry_ptr = 31;
+		skel->bss->telemetry[i].fexit_pptr = 32;
+		skel->bss->telemetry[i].fexit_ptr = 33;
+	}
+
+	err = fentry_fexit_void_pptr_test__attach(skel);
+	if (!ASSERT_OK(err, "fentry_fexit_void_pptr_test__attach"))
+		goto cleanup;
+
+	/* Trigger fentry/fexit programs. */
+	prog_fd = bpf_program__fd(skel->progs.test_fentry_void_pptr);
+	err = bpf_prog_test_run_opts(prog_fd, &topts);
+	ASSERT_OK(err, "test_run");
+	ASSERT_EQ(topts.retval, 0, "test_run retval");
+	for (i = 0; i < ARRAY_SIZE(skel->bss->telemetry); ++i) {
+		ASSERT_EQ(skel->bss->telemetry[i].fentry_called, 1, "fentry_called");
+		ASSERT_EQ(skel->bss->telemetry[i].fexit_called, 1, "fexit_called");
+		ASSERT_EQ(skel->bss->telemetry[i].fentry_pptr, skel->bss->telemetry[i].fexit_pptr,
+			"fentry_pptr == fexit_pptr");
+		ASSERT_EQ(skel->bss->telemetry[i].fexit_ptr, skel->bss->telemetry[i].fentry_ptr,
+			"fexit_ptr");
+		ASSERT_EQ(skel->bss->telemetry[i].fentry_pptr_addr_valid,
+			skel->bss->telemetry[i].fexit_pptr_addr_valid, "fexit_pptr_addr_valid");
+		if (!skel->bss->telemetry[i].fentry_pptr_addr_valid) {
+			/* Should be set to 0 by kernel address boundaries check or an exception handler. */
+			ASSERT_EQ(skel->bss->telemetry[i].fentry_ptr, 0, "fentry_ptr");
+			ASSERT_EQ(skel->bss->telemetry[i].fexit_ptr, 0, "fexit_ptr");
+		}
+	}
+cleanup:
+	fentry_fexit_void_pptr_test__destroy(skel);
+}
+
+static void test_fentry_fexit_void_ppptr(void)
+{
+	struct fentry_fexit_void_ppptr_test *skel = NULL;
+	int err, prog_fd;
+	LIBBPF_OPTS(bpf_test_run_opts, topts);
+
+	skel = fentry_fexit_void_ppptr_test__open_and_load();
+	if (!ASSERT_OK_PTR(skel, "fentry_fexit_void_ppptr_test__open_and_load"))
+		return;
+
+	/* Poison some values which should be modified by BPF programs */
+	skel->bss->fentry_pptr = 31;
+
+	err = fentry_fexit_void_ppptr_test__attach(skel);
+	if (!ASSERT_OK(err, "fentry_fexit_void_ppptr_test__attach"))
+		goto cleanup;
+
+	/* Trigger fentry/fexit programs */
+	prog_fd = bpf_program__fd(skel->progs.test_fentry_void_ppptr);
+	err = bpf_prog_test_run_opts(prog_fd, &topts);
+	ASSERT_OK(err, "test_run");
+	ASSERT_EQ(topts.retval, 0, "test_run retval");
+
+	/* Verify invalid memory access results in zeroed register */
+	ASSERT_EQ(skel->bss->fentry_called, 1, "fentry_called");
+	ASSERT_EQ(skel->bss->fentry_pptr, 0, "fentry_pptr");
+
+	/* Verify fexit captured correct values and return value */
+	ASSERT_EQ(skel->bss->fexit_called, 1, "fexit_called");
+	ASSERT_EQ(skel->bss->fexit_retval, (u64)ERR_PTR(-ENOMEM), "fexit_retval");
+
+cleanup:
+	fentry_fexit_void_ppptr_test__destroy(skel);
+}
+
+void test_fentry_fexit_multi_level_ptr(void)
+{
+	if (test__start_subtest("pptr_nullable"))
+		test_fentry_fexit_pptr_nullable();
+	if (test__start_subtest("pptr"))
+		test_fentry_fexit_pptr();
+	if (test__start_subtest("void_pptr"))
+		test_fentry_fexit_void_pptr();
+	if (test__start_subtest("void_ppptr"))
+		test_fentry_fexit_void_ppptr();
+}
diff --git a/tools/testing/selftests/bpf/prog_tests/verifier.c b/tools/testing/selftests/bpf/prog_tests/verifier.c
index 8cdfd74c95d7..5bcc6406c0b2 100644
--- a/tools/testing/selftests/bpf/prog_tests/verifier.c
+++ b/tools/testing/selftests/bpf/prog_tests/verifier.c
@@ -115,6 +115,7 @@
 #include "verifier_lsm.skel.h"
 #include "verifier_jit_inline.skel.h"
 #include "irq.skel.h"
+#include "verifier_ctx_multilevel_ptr.skel.h"
 
 #define MAX_ENTRIES 11
 
@@ -259,6 +260,7 @@ void test_verifier_lsm(void)                  { RUN(verifier_lsm); }
 void test_irq(void)			      { RUN(irq); }
 void test_verifier_mtu(void)		      { RUN(verifier_mtu); }
 void test_verifier_jit_inline(void)               { RUN(verifier_jit_inline); }
+void test_verifier_ctx_multilevel_ptr(void)       { RUN(verifier_ctx_multilevel_ptr); }
 
 static int init_test_val_map(struct bpf_object *obj, char *map_name)
 {
diff --git a/tools/testing/selftests/bpf/progs/fentry_fexit_pptr_nullable_test.c b/tools/testing/selftests/bpf/progs/fentry_fexit_pptr_nullable_test.c
new file mode 100644
index 000000000000..9cfd21a042e6
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/fentry_fexit_pptr_nullable_test.c
@@ -0,0 +1,56 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (c) 2026 CrowdStrike, Inc. */
+#include <linux/bpf.h>
+#include <bpf/bpf_helpers.h>
+#include <bpf/bpf_tracing.h>
+#include <bpf/bpf_core_read.h>
+
+char _license[] SEC("license") = "GPL";
+
+struct bpf_fentry_test_pptr_t {
+	__u32 value1;
+	__u32 value2;
+};
+
+/*
+ * Workaround for a bug in LLVM:
+ * fatal error: error in backend: Empty type name for BTF_TYPE_ID_REMOTE reloc
+ */
+typedef struct bpf_fentry_test_pptr_t *bpf_fentry_test_pptr_p;
+
+__u32 fentry_called = 0;
+__u32 fentry_ptr_field_value1 = 0;
+__u32 fentry_ptr_field_value2 = 0;
+__u32 fexit_called = 0;
+__u32 fexit_ptr_field_value1 = 0;
+__u32 fexit_ptr_field_value2 = 0;
+__u32 fexit_retval = 0;
+
+SEC("fentry/bpf_fentry_test11_pptr_nullable")
+int BPF_PROG(test_fentry_pptr_nullable, struct bpf_fentry_test_pptr_t **pptr__nullable)
+{
+	struct bpf_fentry_test_pptr_t *ptr;
+
+	fentry_called = 1;
+	/* For scalars, the verifier does not enforce NULL pointer checks. */
+	ptr = *bpf_core_cast(pptr__nullable, bpf_fentry_test_pptr_p);
+	bpf_probe_read_kernel(&fentry_ptr_field_value1, sizeof(fentry_ptr_field_value1), &ptr->value1);
+	bpf_probe_read_kernel(&fentry_ptr_field_value2, sizeof(fentry_ptr_field_value2), &ptr->value2);
+	return 0;
+}
+
+SEC("fexit/bpf_fentry_test11_pptr_nullable")
+int BPF_PROG(test_fexit_pptr_nullable, struct bpf_fentry_test_pptr_t **pptr__nullable, int ret)
+{
+	struct bpf_fentry_test_pptr_t **pptr;
+	struct bpf_fentry_test_pptr_t *ptr;
+
+	fexit_called = 1;
+	fexit_retval = ret;
+	/* For scalars, the verifier does not enforce NULL pointer checks. */
+	pptr = bpf_core_cast(pptr__nullable, bpf_fentry_test_pptr_p);
+	ptr = bpf_core_cast((*pptr), struct bpf_fentry_test_pptr_t);
+	fexit_ptr_field_value1 = ptr->value1;
+	fexit_ptr_field_value2 = ptr->value2;
+	return 0;
+}
diff --git a/tools/testing/selftests/bpf/progs/fentry_fexit_pptr_test.c b/tools/testing/selftests/bpf/progs/fentry_fexit_pptr_test.c
new file mode 100644
index 000000000000..77c5c09d7117
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/fentry_fexit_pptr_test.c
@@ -0,0 +1,67 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (c) 2026 CrowdStrike, Inc. */
+#include <linux/bpf.h>
+#include <bpf/bpf_helpers.h>
+#include <bpf/bpf_tracing.h>
+#include <bpf/bpf_core_read.h>
+
+char _license[] SEC("license") = "GPL";
+
+#define TELEMETRY_COUNT 2
+
+struct {
+	__u32 id;
+	__u32 fentry_called;
+	__u32 fexit_called;
+	__u64 fentry_pptr;
+	__u64 fentry_ptr;
+	__u64 fexit_pptr;
+	__u64 fexit_ptr;
+	__u64 fexit_ret_pptr;
+	__u64 fexit_ret_ptr;
+} telemetry[TELEMETRY_COUNT];
+
+volatile unsigned int current_index = 0;
+
+/*
+ * Workaround for a bug in LLVM:
+ * fatal error: error in backend: Empty type name for BTF_TYPE_ID_REMOTE reloc
+ */
+typedef __u32 *__u32_p;
+
+SEC("fentry/bpf_fentry_test12_pptr")
+int BPF_PROG(test_fentry_pptr, __u32 id, __u32 **pptr)
+{
+	void *ptr;
+	unsigned int i = current_index;
+
+	if (i >= TELEMETRY_COUNT)
+		return 0;
+
+	if (bpf_probe_read_kernel(&ptr, sizeof(ptr), pptr) != 0)
+		ptr = NULL;
+
+	telemetry[i].id = id;
+	telemetry[i].fentry_called = 1;
+	telemetry[i].fentry_pptr = (__u64)pptr;
+	telemetry[i].fentry_ptr = (__u64)ptr;
+	return 0;
+}
+
+SEC("fexit/bpf_fentry_test12_pptr")
+int BPF_PROG(test_fexit_pptr, __u32 id, __u32 **pptr, __u32 **ret)
+{
+	unsigned int i = current_index;
+
+	if (i >= TELEMETRY_COUNT)
+		return 0;
+
+	telemetry[i].fexit_called = 1;
+	telemetry[i].fexit_pptr = (__u64)pptr;
+	telemetry[i].fexit_ptr = (__u64)*bpf_core_cast(pptr, __u32_p);
+	telemetry[i].fexit_ret_pptr = (__u64)ret;
+	telemetry[i].fexit_ret_ptr = ret ? (__u64)*bpf_core_cast(ret, __u32_p) : 0;
+
+	current_index = i + 1;
+	return 0;
+}
diff --git a/tools/testing/selftests/bpf/progs/fentry_fexit_void_ppptr_test.c b/tools/testing/selftests/bpf/progs/fentry_fexit_void_ppptr_test.c
new file mode 100644
index 000000000000..26cb7285f808
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/fentry_fexit_void_ppptr_test.c
@@ -0,0 +1,38 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (c) 2026 CrowdStrike, Inc. */
+#include <linux/bpf.h>
+#include <bpf/bpf_helpers.h>
+#include <bpf/bpf_tracing.h>
+#include <bpf/bpf_core_read.h>
+
+char _license[] SEC("license") = "GPL";
+
+__u32 fentry_called = 0;
+__u32 fexit_called = 0;
+__u64 fentry_pptr = 0;
+__u64 fexit_retval = 0;
+
+typedef void **volatile *const ppvpc_t;
+
+/*
+ * Workaround for a bug in LLVM:
+ * fatal error: error in backend: Empty type name for BTF_TYPE_ID_REMOTE reloc
+ */
+typedef void **void_pp;
+
+SEC("fentry/bpf_fentry_test14_ppptr")
+int BPF_PROG(test_fentry_void_ppptr, ppvpc_t ppptr)
+{
+	fentry_called = 1;
+	/* Invalid memory access is fixed by boundaries check or exception handler */
+	fentry_pptr = (__u64)*bpf_core_cast((void ***)ppptr, void_pp);
+	return 0;
+}
+
+SEC("fexit/bpf_fentry_test14_ppptr")
+int BPF_PROG(test_fexit_void_ppptr, ppvpc_t ppptr, void ***ret)
+{
+	fexit_called = 1;
+	fexit_retval = ret ? (__u64)ret : 0;
+	return 0;
+}
diff --git a/tools/testing/selftests/bpf/progs/fentry_fexit_void_pptr_test.c b/tools/testing/selftests/bpf/progs/fentry_fexit_void_pptr_test.c
new file mode 100644
index 000000000000..588050b9607d
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/fentry_fexit_void_pptr_test.c
@@ -0,0 +1,71 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (c) 2026 CrowdStrike, Inc. */
+#include <linux/bpf.h>
+#include <bpf/bpf_helpers.h>
+#include <bpf/bpf_tracing.h>
+#include <bpf/bpf_core_read.h>
+
+char _license[] SEC("license") = "GPL";
+
+#define TELEMETRY_COUNT 3
+
+struct {
+	__u32 fentry_called;
+	__u32 fexit_called;
+	__u32 fentry_pptr_addr_valid;
+	__u32 fexit_pptr_addr_valid;
+	__u64 fentry_pptr;
+	__u64 fentry_ptr;
+	__u64 fexit_pptr;
+	__u64 fexit_ptr;
+} telemetry[TELEMETRY_COUNT];
+
+volatile unsigned int current_index = 0;
+
+/*
+ * Workaround for a bug in LLVM:
+ * fatal error: error in backend: Empty type name for BTF_TYPE_ID_REMOTE reloc
+ */
+typedef void *void_p;
+
+SEC("fentry/bpf_fentry_test13_pptr")
+int BPF_PROG(test_fentry_void_pptr, void **pptr)
+{
+	void *ptr;
+	unsigned int i = current_index;
+
+	if (i >= TELEMETRY_COUNT)
+		return 0;
+
+	telemetry[i].fentry_pptr_addr_valid =
+		(bpf_probe_read_kernel(&ptr, sizeof(ptr), pptr) == 0);
+	if (!telemetry[i].fentry_pptr_addr_valid)
+		ptr = NULL;
+
+	telemetry[i].fentry_called = 1;
+	telemetry[i].fentry_pptr = (__u64)pptr;
+	telemetry[i].fentry_ptr = (__u64)ptr;
+	return 0;
+}
+
+SEC("fexit/bpf_fentry_test13_pptr")
+int BPF_PROG(test_fexit_void_pptr, void **pptr, __u8 ret)
+{
+	unsigned int i = current_index;
+
+	if (i >= TELEMETRY_COUNT)
+		return 0;
+
+	telemetry[i].fexit_called = 1;
+	telemetry[i].fexit_pptr = (__u64)pptr;
+	telemetry[i].fexit_pptr_addr_valid = ret;
+
+	/*
+	 * For invalid addresses, the destination register for *dptr is set
+	 * to 0 by the BPF exception handler, JIT address range check, or
+	 * the BPF interpreter.
+	 */
+	telemetry[i].fexit_ptr = (__u64)*bpf_core_cast(pptr, void_p);
+	current_index = i + 1;
+	return 0;
+}
diff --git a/tools/testing/selftests/bpf/progs/verifier_ctx_multilevel_ptr.c b/tools/testing/selftests/bpf/progs/verifier_ctx_multilevel_ptr.c
new file mode 100644
index 000000000000..e508a6fbf430
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/verifier_ctx_multilevel_ptr.c
@@ -0,0 +1,435 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Verifier tests for double and triple pointer parameter handling
+ * Copyright (c) 2026 CrowdStrike, Inc.
+ */
+
+#include <linux/bpf.h>
+#include <bpf/bpf_helpers.h>
+#include <bpf/bpf_tracing.h>
+#include <bpf/bpf_core_read.h>
+#include "bpf_misc.h"
+
+SEC("fentry/bpf_fentry_test11_pptr_nullable")
+__description("fentry/double pointer parameter - valid ctx access")
+__success __retval(0)
+__naked void ctx_double_ptr_fentry_valid_ctx_access(void)
+{
+	asm volatile ("				\
+	/* load double pointer - SCALAR_VALUE */\
+	r2 = *(u64 *)(r1 + 0);		\
+	r0 = 0;						\
+	exit;						\
+"	::: __clobber_all);
+}
+
+SEC("fexit/bpf_fentry_test11_pptr_nullable")
+__description("fexit/double pointer parameter - valid ctx access")
+__success __retval(0)
+__naked void ctx_double_ptr_fexit_valid_ctx_access(void)
+{
+	asm volatile ("				\
+	/* load double pointer - SCALAR_VALUE */\
+	r2 = *(u64 *)(r1 + 0);		\
+	r0 = 0;						\
+	exit;						\
+"	::: __clobber_all);
+}
+
+SEC("fentry/bpf_fentry_test11_pptr_nullable")
+__description("fentry/double pointer nullable parameter - valid ctx access")
+__success __retval(0)
+__naked void ctx_double_ptr_valid_ctx_access_nullable(void)
+{
+	asm volatile ("				\
+	/* load double pointer - SCALAR_VALUE */\
+	r2 = *(u64 *)(r1 + 0);		\
+	r0 = 0;						\
+	exit;						\
+"	::: __clobber_all);
+}
+
+SEC("fentry/bpf_fentry_test11_pptr_nullable")
+__description("fentry/double pointer nullable parameter - invalid load with scalar")
+__failure __msg("R2 invalid mem access 'scalar'")
+__naked void ctx_double_ptr_invalid_load(void)
+{
+	asm volatile ("				\
+	/* load double pointer - SCALAR_VALUE */\
+	r2 = *(u64 *)(r1 + 0);		\
+	r3 = *(u64 *)(r2 + 0);		\
+	r0 = 0;						\
+	exit;						\
+"	::: __clobber_all);
+}
+
+SEC("fentry/bpf_fentry_test11_pptr_nullable")
+__description("fentry/double pointer nullable parameter - invalid load with scalar by offset")
+__failure __msg("R2 invalid mem access 'scalar'")
+__naked void ctx_double_ptr_invalid_load_with_offset(void)
+{
+	asm volatile ("				\
+	/* load double pointer - SCALAR_VALUE */\
+	r2 = *(u64 *)(r1 + 0);		\
+	r3 = *(u64 *)(r2 + 0x80);		\
+	r0 = 0;						\
+	exit;						\
+"	::: __clobber_all);
+}
+
+SEC("fentry/bpf_fentry_test11_pptr_nullable")
+__description("fentry/double pointer nullable parameter - invalid store by scalar")
+__failure __msg("R2 invalid mem access 'scalar'")
+__naked void ctx_double_ptr_store_with_scalar(void)
+{
+	asm volatile ("				\
+	/* load double pointer - SCALAR_VALUE */\
+	r2 = *(u64 *)(r1 + 0);		\
+	*(u64 *)(r2 + 0x0) = 1;		\
+	r0 = 0;						\
+	exit;						\
+"	::: __clobber_all);
+}
+
+SEC("fentry/bpf_fentry_test14_ppptr")
+__description("fentry/triple pointer parameter - valid ctx access")
+__success __retval(0)
+__naked void ctx_triple_ptr_valid_ctx_access(void)
+{
+	asm volatile ("				\
+	/* load triple pointer - SCALAR_VALUE */\
+	r2 = *(u64 *)(r1 + 0);		\
+	r0 = 0;						\
+	exit;						\
+"	::: __clobber_all);
+}
+
+SEC("fentry/bpf_fentry_test14_ppptr")
+__description("fentry/triple pointer parameter - invalid load with scalar")
+__failure __msg("R2 invalid mem access 'scalar'")
+__naked void ctx_triple_ptr_load_with_scalar(void)
+{
+	asm volatile ("				\
+	/* load triple pointer - SCALAR_VALUE */\
+	r2 = *(u64 *)(r1 + 0);		\
+	r3 = *(u64 *)(r2 + 0);		\
+	r0 = 0;						\
+	exit;						\
+"	::: __clobber_all);
+}
+
+SEC("fentry/bpf_fentry_test14_ppptr")
+__description("fentry/triple pointer parameter - invalid store with scalar")
+__failure __msg("R2 invalid mem access 'scalar'")
+__naked void ctx_triple_ptr_store_with_scalar(void)
+{
+	asm volatile ("				\
+	/* load triple pointer - SCALAR_VALUE */\
+	r2 = *(u64 *)(r1 + 0);		\
+	*(u64 *)(r2 + 0) = 1;		\
+	r0 = 0;						\
+	exit;						\
+"	::: __clobber_all);
+}
+
+SEC("lsm/sb_eat_lsm_opts")
+__description("lsm/double pointer parameter trusted - valid ctx access")
+__success
+__naked void sb_eat_lsm_opts_trusted_valid_ctx_access(void)
+{
+	asm volatile ("				\
+	/* load double pointer - SCALAR_VALUE */\
+	r2 = *(u64 *)(r1 + 8);		\
+	r0 = 0;						\
+	exit;						\
+"	::: __clobber_all);
+}
+
+SEC("lsm/sb_eat_lsm_opts")
+__description("lsm/double pointer parameter trusted - invalid load with scalar")
+__failure __msg("R2 invalid mem access 'scalar'")
+__naked void sb_eat_lsm_opts_trusted_load_with_scalar(void)
+{
+	asm volatile ("				\
+	/* load double pointer - SCALAR_VALUE */\
+	r2 = *(u64 *)(r1 + 8);		\
+	r3 = *(u64 *)(r2 + 0);		\
+	r0 = 0;						\
+	exit;						\
+"	::: __clobber_all);
+}
+
+SEC("lsm/sb_eat_lsm_opts")
+__description("lsm/double pointer parameter trusted - invalid store with scalar")
+__failure __msg("R2 invalid mem access 'scalar'")
+__naked void sb_eat_lsm_opts_trusted_store_with_scalar(void)
+{
+	asm volatile ("				\
+	/* load double pointer - SCALAR_VALUE */\
+	r2 = *(u64 *)(r1 + 8);		\
+	*(u64 *)(r2 + 0) = 1;		\
+	r0 = 0;						\
+	exit;						\
+"	::: __clobber_all);
+}
+
+struct bpf_fentry_test_pptr_t;
+
+SEC("fentry/bpf_fentry_test11_pptr_nullable")
+__description("fentry/double pointer parameter - bpf helpers with nullable var")
+__success __retval(0)
+int BPF_PROG(ctx_double_ptr_nulable_var_access_bpf_helpers,
+	struct bpf_fentry_test_pptr_t **pptr__nullable)
+{
+	/* Check compatibility with BPF helpers; NULL checks should not be required. */
+	void *ptr;
+
+	bpf_probe_read_kernel(&ptr, sizeof(ptr), pptr__nullable);
+	return 0;
+}
+
+/*
+ * Workaround for a bug in LLVM:
+ * fatal error: error in backend: Empty type name for BTF_TYPE_ID_REMOTE reloc
+ */
+typedef __u32 *__u32_p;
+
+/*
+ * Workaround for:
+ * kfunc bpf_rdonly_cast type ID argument must be of a struct or void
+ */
+struct __u32_wrap {
+	__u32 v;
+};
+
+SEC("fexit/bpf_fentry_test12_pptr")
+__description("fexit/double pointer return value - valid dereference of return val")
+__success __retval(0)
+int BPF_PROG(ctx_double_ptr_return_access, __u32 id,
+	__u32 **pptr, __u32 **ret)
+{
+	__u32 **ppu32;
+	struct __u32_wrap *pu32;
+	ppu32 = bpf_core_cast(ret, __u32_p);
+	pu32 = bpf_core_cast(ppu32, struct __u32_wrap);
+	bpf_printk("%d", pu32->v);
+	return 0;
+}
+
+SEC("fexit/bpf_fentry_test12_pptr")
+__description("fexit/double pointer parameter - bpf helpers with return val")
+__success __retval(0)
+int BPF_PROG(ctx_double_ptr_return_access_bpf_helpers, __u32 id,
+	__u32 **pptr, __u32 **ret)
+{
+	/* Check compatibility with BPF helpers; NULL checks should not be required. */
+	void *ptr;
+
+	bpf_probe_read_kernel(&ptr, sizeof(ptr), pptr);
+	bpf_probe_read_kernel(&ptr, sizeof(ptr), ret);
+	return 0;
+}
+
+SEC("fentry/bpf_fentry_test11_pptr_nullable")
+__description("fentry/double pointer parameter - bpf helpers with nullable var, direct ctx pointer")
+__success __retval(0)
+int BPF_PROG(ctx_double_ptr_nulable_var_access_bpf_helpers_ctx,
+	struct bpf_fentry_test_pptr_t **pptr__nullable)
+{
+	/* Check compatibility with BPF helpers; NULL checks should not be required. */
+	void *ptr;
+
+	bpf_probe_read_kernel(&ptr, sizeof(ptr), &ctx[0] /*pptr__nullable*/);
+	return 0;
+}
+
+SEC("fexit/bpf_fentry_test12_pptr")
+__description("fexit/double pointer parameter - bpf helpers with return val, direct ctx pointer")
+__success __retval(0)
+int BPF_PROG(ctx_double_ptr_return_access_bpf_helpers_ctx, __u32 id,
+	__u32 **pptr, __u32 **ret)
+{
+	/* Check compatibility with BPF helpers; NULL checks should not be required. */
+	void *ptr;
+
+	bpf_probe_read_kernel(&ptr, sizeof(ptr), &ctx[1] /*pptr*/);
+	bpf_probe_read_kernel(&ptr, sizeof(ptr), &ctx[2] /*ret*/);
+	return 0;
+}
+
+struct bpf_fentry_test_pptr_t {
+	__u32 value1;
+	__u32 value2;
+};
+
+/*
+ * Workaround for a bug in LLVM:
+ * fatal error: error in backend: Empty type name for BTF_TYPE_ID_REMOTE reloc
+ */
+typedef struct bpf_fentry_test_pptr_t *bpf_fentry_test_pptr_p;
+
+SEC("fentry/bpf_fentry_test11_pptr_nullable")
+__description("fentry/double pointer parameter - dereference followed by valid load of field 1")
+__success __retval(0)
+int BPF_PROG(ctx_double_ptr_deref_with_field_1_load,
+	struct bpf_fentry_test_pptr_t **pptr__nullable)
+{
+	struct bpf_fentry_test_pptr_t **pptr;
+	struct bpf_fentry_test_pptr_t *ptr;
+
+	pptr = bpf_core_cast(pptr__nullable, bpf_fentry_test_pptr_p);
+	ptr = bpf_core_cast((*pptr), struct bpf_fentry_test_pptr_t);
+	bpf_printk("%d", ptr->value1);
+	return 0;
+}
+
+SEC("fentry/bpf_fentry_test11_pptr_nullable")
+__description("fentry/double pointer parameter - dereference followed by valid load of field 2")
+__success __retval(0)
+int BPF_PROG(ctx_double_ptr_deref_with_field_2_load, struct bpf_fentry_test_pptr_t **pptr__nullable)
+{
+	struct bpf_fentry_test_pptr_t **pptr;
+	struct bpf_fentry_test_pptr_t *ptr;
+
+	pptr = bpf_core_cast(pptr__nullable, bpf_fentry_test_pptr_p);
+	ptr = bpf_core_cast((*pptr), struct bpf_fentry_test_pptr_t);
+	bpf_printk("%d", ptr->value2);
+	return 0;
+}
+
+SEC("fentry/bpf_fentry_test11_pptr_nullable")
+__description("fentry/double pointer parameter - dereference followed by invalid out-of-bounds offset load")
+__failure __msg("access beyond struct bpf_fentry_test_pptr_t at off 128 size 4")
+int BPF_PROG(ctx_double_ptr_deref_with_load_by_positive_out_of_bound_offset,
+	struct bpf_fentry_test_pptr_t **pptr__nullable)
+{
+	struct bpf_fentry_test_pptr_t **pptr;
+	struct bpf_fentry_test_pptr_t *ptr;
+	__u32 value;
+
+	pptr = bpf_core_cast(pptr__nullable, bpf_fentry_test_pptr_p);
+	ptr = bpf_core_cast((*pptr), struct bpf_fentry_test_pptr_t);
+
+	asm volatile ("					\
+		r2 = %1;					\
+		/* Load with out-of-bounds offset */\
+		%0 = *(u32 *)(r2 + 0x80)	\
+		" : "=r" (value) : "r" (ptr) : "r2");
+
+	bpf_printk("%d", value);
+	return 0;
+}
+
+SEC("fentry/bpf_fentry_test11_pptr_nullable")
+__description("fentry/double pointer parameter - dereference followed by invalid out-of-bounds offset load")
+__failure __msg("R2 is ptr_bpf_fentry_test_pptr_t invalid negative access: off=-128")
+int BPF_PROG(ctx_double_ptr_deref_with_load_by_negative_out_of_bound_offset,
+	struct bpf_fentry_test_pptr_t **pptr__nullable)
+{
+	struct bpf_fentry_test_pptr_t **pptr;
+	struct bpf_fentry_test_pptr_t *ptr;
+	__u32 value;
+
+	pptr = bpf_core_cast(pptr__nullable, bpf_fentry_test_pptr_p);
+	ptr = bpf_core_cast((*pptr), struct bpf_fentry_test_pptr_t);
+
+	asm volatile ("					\
+		r2 = %1;					\
+		/* Load with out-of-bounds offset */\
+		%0 = *(u32 *)(r2 - 0x80);	\
+		" : "=r" (value) : "r" (ptr) : "r2");
+
+	bpf_printk("%d", value);
+	return 0;
+}
+
+SEC("fentry/bpf_fentry_test11_pptr_nullable")
+__description("fentry/double pointer parameter - dereference followed by invalid store to field 1")
+__failure __msg("only read is supported")
+int BPF_PROG(ctx_double_ptr_deref_with_field_1_modification, struct bpf_fentry_test_pptr_t **pptr__nullable)
+{
+	struct bpf_fentry_test_pptr_t **pptr;
+	struct bpf_fentry_test_pptr_t *ptr;
+
+	pptr = bpf_core_cast(pptr__nullable, bpf_fentry_test_pptr_p);
+	ptr = bpf_core_cast((*pptr), struct bpf_fentry_test_pptr_t);
+
+	asm volatile ("					\
+		/* Load immediate 1 into w2 */\
+		w2 = 1;						\
+		/* Store to ptr->value1 */	\
+		*(u32 *)(%0 + 0) = r2;		\
+		" :: "r" (ptr) : "r2");
+
+	return 0;
+}
+
+SEC("fentry/bpf_fentry_test11_pptr_nullable")
+__description("fentry/double pointer parameter - dereference followed by invalid store to field 2")
+__failure __msg("only read is supported")
+int BPF_PROG(ctx_double_ptr_deref_with_field_2_modification,
+	struct bpf_fentry_test_pptr_t **pptr__nullable)
+{
+	struct bpf_fentry_test_pptr_t **pptr;
+	struct bpf_fentry_test_pptr_t *ptr;
+
+	pptr = bpf_core_cast(pptr__nullable, bpf_fentry_test_pptr_p);
+	ptr = bpf_core_cast((*pptr), struct bpf_fentry_test_pptr_t);
+
+	asm volatile ("					\
+		/* Load immediate 2 into w2 */\
+		w2 = 2;						\
+		/* Store to ptr->value2 */	\
+		*(u32 *)(%0 + 4) = r2;		\
+		" :: "r" (ptr) : "r2");
+
+	return 0;
+}
+
+SEC("fentry/bpf_fentry_test11_pptr_nullable")
+__description("fentry/double pointer parameter - dereference followed by invalid store to positive offset beyond struct boundaries")
+__failure __msg("only read is supported")
+int BPF_PROG(ctx_double_ptr_deref_with_store_by_positive_invalid_offset,
+	struct bpf_fentry_test_pptr_t **pptr__nullable)
+{
+	struct bpf_fentry_test_pptr_t **pptr;
+	struct bpf_fentry_test_pptr_t *ptr;
+
+	pptr = bpf_core_cast(pptr__nullable, bpf_fentry_test_pptr_p);
+	ptr = bpf_core_cast((*pptr), struct bpf_fentry_test_pptr_t);
+
+	asm volatile ("					\
+		r3 = %0;					\
+		/* Load immediate 3 into w2 */\
+		w2 = 3;						\
+		/* Store with offset outside struct size */	\
+		*(u32 *)(r3 + 0x80) = r2;		\
+		" :: "r" (ptr) : "r2", "r3");
+
+	return 0;
+}
+
+SEC("fentry/bpf_fentry_test11_pptr_nullable")
+__description("fentry/double pointer parameter - dereference followed by invalid store to negative offset beyond struct boundaries")
+__failure __msg("R3 is ptr_bpf_fentry_test_pptr_t invalid negative access: off=-128")
+int BPF_PROG(ctx_double_ptr_deref_with_store_by_negative_invalid_offset,
+	struct bpf_fentry_test_pptr_t **pptr__nullable)
+{
+	struct bpf_fentry_test_pptr_t **pptr;
+	struct bpf_fentry_test_pptr_t *ptr;
+
+	pptr = bpf_core_cast(pptr__nullable, bpf_fentry_test_pptr_p);
+	ptr = bpf_core_cast((*pptr), struct bpf_fentry_test_pptr_t);
+
+	asm volatile ("					\
+		r3 = %0;					\
+		/* Load immediate 3 into w2 */\
+		w2 = 3;						\
+		/* Store with offset outside struct size */	\
+		*(u32 *)(r3 - 0x80) = r2;		\
+		" :: "r" (ptr) : "r2", "r3");
+
+	return 0;
+}
+
+char _license[] SEC("license") = "GPL";
-- 
2.34.1