[LTP] [PATCH 4/4] futex_cmp_requeue03: Add EFAULT and EACCES error coverage test

[Michael Menasherov]

---
 runtest/syscalls                              |  1 +
 testcases/kernel/syscalls/futex/.gitignore    |  1 +
 .../syscalls/futex/futex_cmp_requeue03.c      | 96 +++++++++++++++++++
 3 files changed, 98 insertions(+)
 create mode 100644 testcases/kernel/syscalls/futex/futex_cmp_requeue03.c

diff --git a/runtest/syscalls b/runtest/syscalls
index 4d85a1d26..65baa44dc 100644
--- a/runtest/syscalls
+++ b/runtest/syscalls
@@ -1908,3 +1908,4 @@ perf_event_open03 perf_event_open03
 futex_wait06 futex_wait06
 futex_wait07 futex_wait07
 futex_wake05 futex_wake05
+futex_cmp_requeue03 futex_cmp_requeue03
diff --git a/testcases/kernel/syscalls/futex/.gitignore b/testcases/kernel/syscalls/futex/.gitignore
index c11546e07..231b6bd25 100644
--- a/testcases/kernel/syscalls/futex/.gitignore
+++ b/testcases/kernel/syscalls/futex/.gitignore
@@ -16,3 +16,4 @@
 /futex_wait06
 /futex_wait07
 /futex_wake05
+/futex_cmp_requeue03
diff --git a/testcases/kernel/syscalls/futex/futex_cmp_requeue03.c b/testcases/kernel/syscalls/futex/futex_cmp_requeue03.c
new file mode 100644
index 000000000..099d5e35c
--- /dev/null
+++ b/testcases/kernel/syscalls/futex/futex_cmp_requeue03.c
@@ -0,0 +1,96 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Copyright (C) 2026 Red Hat, Inc.
+ */
+
+/*\
+ * Check that futex(FUTEX_CMP_REQUEUE) returns EFAULT when uaddr or
+ * uaddr2 points to unmapped memory, and EACCES (or EFAULT on older kernels)
+ * when uaddr points to memory without read permission (PROT_NONE).
+ *
+ * The EACCES behavior for PROT_NONE was introduced in kernel 5.9.
+ */
+
+#include <errno.h>
+#include <sys/mman.h>
+
+#include "futextest.h"
+
+static futex_t futex_var = FUTEX_INITIALIZER;
+static futex_t *prot_none_addr;
+
+static struct futex_test_variants variants[] = {
+#if (__NR_futex != __LTP__NR_INVALID_SYSCALL)
+	{ .fntype = FUTEX_FN_FUTEX, .desc = "syscall with old kernel spec"},
+#endif
+
+#if (__NR_futex_time64 != __LTP__NR_INVALID_SYSCALL)
+	{ .fntype = FUTEX_FN_FUTEX64, .desc = "syscall time64 with kernel spec"},
+#endif
+};
+
+static struct testcase {
+	const char *desc;
+	futex_t *uaddr;
+	futex_t *uaddr2;
+	int exp_errno;
+} testcases[3];
+
+static void run(unsigned int n)
+{
+	struct futex_test_variants *tv = &variants[tst_variant];
+	struct testcase *tc = &testcases[n];
+
+	TST_EXP_FAIL(futex_cmp_requeue(tv->fntype, tc->uaddr, futex_var,
+		tc->uaddr2, 1, 1, 0), tc->exp_errno, "%s", tc->desc);
+}
+
+static void setup(void)
+{
+	struct futex_test_variants *tv = &variants[tst_variant];
+	size_t pagesize = getpagesize();
+	futex_t *unmapped;
+
+	tst_res(TINFO, "Testing variant: %s", tv->desc);
+	futex_supported_by_kernel(tv->fntype);
+
+	unmapped = SAFE_MMAP(NULL, pagesize, PROT_READ | PROT_WRITE,
+		MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
+	SAFE_MUNMAP(unmapped, pagesize);
+
+	prot_none_addr = SAFE_MMAP(NULL, pagesize, PROT_NONE,
+		MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
+
+	testcases[0] = (struct testcase){
+		.desc = "uaddr unmapped",
+		.uaddr = unmapped,
+		.uaddr2 = &futex_var,
+		.exp_errno = EFAULT,
+	};
+	testcases[1] = (struct testcase){
+		.desc = "uaddr2 unmapped",
+		.uaddr = &futex_var,
+		.uaddr2 = unmapped,
+		.exp_errno = EFAULT,
+	};
+	testcases[2] = (struct testcase){
+		.desc = "uaddr PROT_NONE",
+		.uaddr = prot_none_addr,
+		.uaddr2 = &futex_var,
+		.exp_errno = tst_kvercmp(5, 9, 0) >= 0 ? EACCES : EFAULT,
+	};
+}
+
+static void cleanup(void)
+{
+	if (prot_none_addr)
+		SAFE_MUNMAP(prot_none_addr, getpagesize());
+}
+
+static struct tst_test test = {
+	.setup = setup,
+	.cleanup = cleanup,
+	.test = run,
+	.tcnt = ARRAY_SIZE(testcases),
+	.test_variants = ARRAY_SIZE(variants),
+};
-- 
2.53.0