[LTP] [PATCH v16 0/2] futex: Add EFAULT coverage for wake and cmp_requeue

[LTP] [PATCH v16 0/2] futex: Add EFAULT coverage for wake and cmp_requeue

[Michael Menasherov via ltp]

futex_wait06 and futex_wait07 were already merged. This series
contains the two remaining patches.

Patch 1/2 (futex_wake05) is v16 — updated based on review feedback
to add a kernel-space address test case and clarify the comment
explaining the different code paths in get_futex_key().

Patch 2/2 (futex_cmp_requeue03) — updated to also cover PROT_NONE
on uaddr2, and has not yet received a human review. Would appreciate
a review of this patch as well.

GitHub PR: https://github.com/linux-test-project/ltp/pull/1301

Michael Menasherov (2):
  futex_wake05: Add EFAULT error coverage test
  futex_cmp_requeue03: Add EFAULT error coverage test

 runtest/syscalls                              |   2 +
 testcases/kernel/syscalls/futex/.gitignore    |   2 +
 .../syscalls/futex/futex_cmp_requeue03.c      | 108 ++++++++++++++++++
 .../kernel/syscalls/futex/futex_wake05.c      | 100 ++++++++++++++++
 4 files changed, 212 insertions(+)
 create mode 100644 testcases/kernel/syscalls/futex/futex_cmp_requeue03.c
 create mode 100644 testcases/kernel/syscalls/futex/futex_wake05.c

-- 
2.54.0


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[LTP] [PATCH v16 1/2] futex_wake05: Add EFAULT error coverage test

[Michael Menasherov via ltp]

futex(FUTEX_WAKE) has no existing test for EFAULT. Add coverage for
unmapped, PROT_NONE, and kernel-space uaddr, each exercising a
different code path in the kernel's address validation.

Signed-off-by: Michael Menasherov <mmenashe@redhat.com>
---
 runtest/syscalls                              |   1 +
 testcases/kernel/syscalls/futex/.gitignore    |   1 +
 .../kernel/syscalls/futex/futex_wake05.c      | 100 ++++++++++++++++++
 3 files changed, 102 insertions(+)
 create mode 100644 testcases/kernel/syscalls/futex/futex_wake05.c

diff --git a/runtest/syscalls b/runtest/syscalls
index a021c79da..67509826f 100644
--- a/runtest/syscalls
+++ b/runtest/syscalls
@@ -1878,6 +1878,7 @@ futex_wake01 futex_wake01
 futex_wake02 futex_wake02
 futex_wake03 futex_wake03
 futex_wake04 futex_wake04
+futex_wake05 futex_wake05
 futex_wait_bitset01 futex_wait_bitset01
 
 memfd_create01 memfd_create01
diff --git a/testcases/kernel/syscalls/futex/.gitignore b/testcases/kernel/syscalls/futex/.gitignore
index 74ac9a926..c11546e07 100644
--- a/testcases/kernel/syscalls/futex/.gitignore
+++ b/testcases/kernel/syscalls/futex/.gitignore
@@ -15,3 +15,4 @@
 /futex_waitv03
 /futex_wait06
 /futex_wait07
+/futex_wake05
diff --git a/testcases/kernel/syscalls/futex/futex_wake05.c b/testcases/kernel/syscalls/futex/futex_wake05.c
new file mode 100644
index 000000000..597426f0a
--- /dev/null
+++ b/testcases/kernel/syscalls/futex/futex_wake05.c
@@ -0,0 +1,100 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Copyright (C) 2026 Red Hat, Inc.
+ * Copyright (C) 2026 Michael Menasherov <mmenashe@redhat.com>
+ */
+
+/*\
+ * Check that futex(FUTEX_WAKE) returns EFAULT when uaddr points to
+ * unmapped, PROT_NONE, or kernel-space memory.
+ *
+ * For opflags=0 (no FUTEX_PRIVATE_FLAG) futex_wake() takes the
+ * shared-futex path in get_futex_key() which must resolve the physical
+ * page.
+ *
+ * The three cases exercise different code paths: a kernel-space address
+ * is rejected by the kernel's user-space address check before physical
+ * page resolution; unmapped memory fails at find_vma() (no VMA exists);
+ * PROT_NONE memory fails at get_user_pages_fast() (VMA exists but page
+ * is inaccessible).
+ */
+
+#include <errno.h>
+#include <sys/mman.h>
+
+#include "futextest.h"
+
+static futex_t *unmapped_addr;
+static futex_t *prot_none_addr;
+static futex_t *kernel_addr = (futex_t *)-1L;
+
+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 **addr;
+	int exp_errno;
+} testcases[] = {
+	{
+		.desc = "uaddr unmapped",
+		.addr = &unmapped_addr,
+		.exp_errno = EFAULT,
+	},
+	{
+		.desc = "uaddr PROT_NONE",
+		.addr = &prot_none_addr,
+		.exp_errno = EFAULT,
+	},
+	{
+		.desc = "uaddr kernel address",
+		.addr = &kernel_addr,
+		.exp_errno = EFAULT,
+	},
+};
+
+static void run(unsigned int n)
+{
+	struct futex_test_variants *tv = &variants[tst_variant];
+	struct testcase *tc = &testcases[n];
+
+	TST_EXP_FAIL(futex_wake(tv->fntype, *tc->addr, 1, 0),
+		     tc->exp_errno, "%s", tc->desc);
+}
+
+static void setup(void)
+{
+	struct futex_test_variants *tv = &variants[tst_variant];
+	size_t pagesize = getpagesize();
+
+	tst_res(TINFO, "Testing variant: %s", tv->desc);
+	futex_supported_by_kernel(tv->fntype);
+
+	unmapped_addr = SAFE_MMAP(NULL, pagesize, PROT_READ | PROT_WRITE,
+				  MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
+	SAFE_MUNMAP((void *)unmapped_addr, pagesize);
+
+	prot_none_addr = SAFE_MMAP(NULL, pagesize, PROT_NONE,
+				   MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
+}
+
+static void cleanup(void)
+{
+	if (prot_none_addr)
+		SAFE_MUNMAP((void *)prot_none_addr, getpagesize());
+}
+
+static struct tst_test test = {
+	.setup = setup,
+	.cleanup = cleanup,
+	.test = run,
+	.tcnt = ARRAY_SIZE(testcases),
+	.test_variants = ARRAY_SIZE(variants),
+};
-- 
2.54.0


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[LTP] [PATCH v16 2/2] futex_cmp_requeue03: Add EFAULT error coverage test

[Michael Menasherov via ltp]

futex(FUTEX_CMP_REQUEUE) has no existing test for EFAULT. Add coverage
for the cases where uaddr or uaddr2 points to unmapped or inaccessible
(PROT_NONE) memory.

Signed-off-by: Michael Menasherov <mmenashe@redhat.com>
---
 runtest/syscalls                              |   1 +
 testcases/kernel/syscalls/futex/.gitignore    |   1 +
 .../syscalls/futex/futex_cmp_requeue03.c      | 108 ++++++++++++++++++
 3 files changed, 110 insertions(+)
 create mode 100644 testcases/kernel/syscalls/futex/futex_cmp_requeue03.c

diff --git a/runtest/syscalls b/runtest/syscalls
index 67509826f..0cb4e3dba 100644
--- a/runtest/syscalls
+++ b/runtest/syscalls
@@ -1864,6 +1864,7 @@ perf_event_open02 perf_event_open02
 
 futex_cmp_requeue01 futex_cmp_requeue01
 futex_cmp_requeue02 futex_cmp_requeue02
+futex_cmp_requeue03 futex_cmp_requeue03
 futex_wait01 futex_wait01
 futex_wait02 futex_wait02
 futex_wait03 futex_wait03
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..c71c8f4cb
--- /dev/null
+++ b/testcases/kernel/syscalls/futex/futex_cmp_requeue03.c
@@ -0,0 +1,108 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Copyright (C) 2026 Red Hat, Inc.
+ * Copyright (C) 2026 Michael Menasherov <mmenashe@redhat.com>
+ */
+
+/*\
+ * Check that futex(FUTEX_CMP_REQUEUE) returns EFAULT when uaddr or
+ * uaddr2 points to unmapped memory, or when uaddr or uaddr2 points to
+ * memory without read permission (PROT_NONE).
+ *
+ * The test uses opflags=0 (no FUTEX_PRIVATE_FLAG) so get_futex_key()
+ * takes the shared-futex path and resolves the physical page; this
+ * lookup fails with EFAULT for unmapped and PROT_NONE addresses.
+ * get_futex_key() is called for both uaddr and uaddr2 before the
+ * *uaddr == val check; futex_var and val are both FUTEX_INITIALIZER.
+ */
+
+#include <errno.h>
+#include <sys/mman.h>
+
+#include "futextest.h"
+
+static futex_t futex_var = FUTEX_INITIALIZER;
+static futex_t *futex_ptr = &futex_var;
+static futex_t *unmapped_addr;
+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[] = {
+	{
+		.desc = "uaddr unmapped",
+		.uaddr = &unmapped_addr,
+		.uaddr2 = &futex_ptr,
+		.exp_errno = EFAULT,
+	},
+	{
+		.desc = "uaddr2 unmapped",
+		.uaddr = &futex_ptr,
+		.uaddr2 = &unmapped_addr,
+		.exp_errno = EFAULT,
+	},
+	{
+		.desc = "uaddr PROT_NONE",
+		.uaddr = &prot_none_addr,
+		.uaddr2 = &futex_ptr,
+		.exp_errno = EFAULT,
+	},
+	{
+		.desc = "uaddr2 PROT_NONE",
+		.uaddr = &futex_ptr,
+		.uaddr2 = &prot_none_addr,
+		.exp_errno = EFAULT,
+	},
+};
+
+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();
+
+	tst_res(TINFO, "Testing variant: %s", tv->desc);
+	futex_supported_by_kernel(tv->fntype);
+
+	unmapped_addr = SAFE_MMAP(NULL, pagesize, PROT_READ | PROT_WRITE,
+				  MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
+	SAFE_MUNMAP((void *)unmapped_addr, pagesize);
+
+	prot_none_addr = SAFE_MMAP(NULL, pagesize, PROT_NONE,
+				   MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
+}
+
+static void cleanup(void)
+{
+	if (prot_none_addr)
+		SAFE_MUNMAP((void *)prot_none_addr, getpagesize());
+}
+
+static struct tst_test test = {
+	.setup = setup,
+	.cleanup = cleanup,
+	.test = run,
+	.tcnt = ARRAY_SIZE(testcases),
+	.test_variants = ARRAY_SIZE(variants),
+};
-- 
2.54.0


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Re: [LTP] futex_wake05: Add EFAULT error coverage test

[linuxtestproject.agent]

Hi Michael,

On Sun, 21 Jun 2026 18:09:50 +0300, Michael Menasherov wrote:
> futex_wake05: Add EFAULT error coverage test

Verdict - Reviewed

---
Note:

The agent can sometimes produce false positives although often its
findings are genuine. If you find issues with the review, please
comment this email or ignore the suggestions.

Regards,
LTP AI Reviewer

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Re: [LTP] [PATCH v16 1/2] futex_wake05: Add EFAULT error coverage test

[Andrea Cervesato via ltp]

Reviewed-by: Andrea Cervesato <andrea.cervesato@suse.com>

--
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SUSE QE Automation Engineer Linux
andrea.cervesato@suse.com

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Re: [LTP] [PATCH v16 2/2] futex_cmp_requeue03: Add EFAULT error coverage test

[Andrea Cervesato via ltp]

Reviewed-by: Andrea Cervesato <andrea.cervesato@suse.com>

--
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SUSE QE Automation Engineer Linux
andrea.cervesato@suse.com

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Re: [LTP] [PATCH v16 1/2] futex_wake05: Add EFAULT error coverage test

[Petr Vorel]

Hi Michael,

> futex(FUTEX_WAKE) has no existing test for EFAULT. Add coverage for
> unmapped, PROT_NONE, and kernel-space uaddr, each exercising a
> different code path in the kernel's address validation.

Generally LGTM, few comments below.

> diff --git a/testcases/kernel/syscalls/futex/futex_wake05.c b/testcases/kernel/syscalls/futex/futex_wake05.c
> new file mode 100644
> index 000000000..597426f0a
> --- /dev/null
> +++ b/testcases/kernel/syscalls/futex/futex_wake05.c
> @@ -0,0 +1,100 @@
> +// SPDX-License-Identifier: GPL-2.0-or-later
> +/*
> + * Copyright (C) 2026 Red Hat, Inc.
> + * Copyright (C) 2026 Michael Menasherov <mmenashe@redhat.com>
> + */
> +
> +/*\
> + * Check that futex(FUTEX_WAKE) returns EFAULT when uaddr points to
> + * unmapped, PROT_NONE, or kernel-space memory.
> + *
> + * For opflags=0 (no FUTEX_PRIVATE_FLAG) futex_wake() takes the
> + * shared-futex path in get_futex_key() which must resolve the physical
> + * page.
> + *
> + * The three cases exercise different code paths: a kernel-space address
> + * is rejected by the kernel's user-space address check before physical
> + * page resolution; unmapped memory fails at find_vma() (no VMA exists);
> + * PROT_NONE memory fails at get_user_pages_fast() (VMA exists but page
> + * is inaccessible).
nit: It'd be more readable using list:

 * The three cases exercise different code paths:

 * - a kernel-space address * is rejected by the kernel's user-space address
 *    check before physical page resolution
 * - unmapped memory fails at find_vma() (no VMA exists)
 * - PROT_NONE memory fails at get_user_pages_fast() (VMA exists but page
 *   is inaccessible)

> + */
> +
> +#include <errno.h>
> +#include <sys/mman.h>
> +
> +#include "futextest.h"
> +
> +static futex_t *unmapped_addr;
> +static futex_t *prot_none_addr;
> +static futex_t *kernel_addr = (futex_t *)-1L;
> +
> +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 **addr;
> +	int exp_errno;
> +} testcases[] = {
> +	{
> +		.desc = "uaddr unmapped",
> +		.addr = &unmapped_addr,
> +		.exp_errno = EFAULT,
> +	},
> +	{
> +		.desc = "uaddr PROT_NONE",
> +		.addr = &prot_none_addr,
> +		.exp_errno = EFAULT,
> +	},
> +	{
> +		.desc = "uaddr kernel address",
> +		.addr = &kernel_addr,
> +		.exp_errno = EFAULT,
nit: If all errors are EFAULT why not use it directly in TST_EXP_FAIL?

But more important is that I got a different errno (EINVAL) on 7.0.x kernel on
old kernel spec:

futex_wake05.c:77: TINFO: Testing variant: syscall with old kernel spec
futex_wake05.c:68: TFAIL: uaddr kernel address expected EFAULT: EINVAL (22)

When compiling 32 bit, I get error on both specs:

PKG_CONFIG_LIBDIR=/usr/lib/pkgconfig CFLAGS=-m32 LDFLAGS=-m32 ./configure
...
futex_wake05.c:77: TINFO: Testing variant: syscall with old kernel spec
futex_wake05.c:68: TPASS: uaddr unmapped : EFAULT (14)
futex_wake05.c:68: TPASS: uaddr PROT_NONE : EFAULT (14)
futex_wake05.c:68: TFAIL: uaddr kernel address expected EFAULT: EINVAL (22)
futex_wake05.c:77: TINFO: Testing variant: syscall time64 with kernel spec
futex_wake05.c:68: TPASS: uaddr unmapped : EFAULT (14)
futex_wake05.c:68: TPASS: uaddr PROT_NONE : EFAULT (14)
futex_wake05.c:68: TFAIL: uaddr kernel address expected EFAULT: EINVAL (22)

I tested very old kernel 4.4 (SLE12-SP3 we still support) and it behaves the
same. Do you really get EFAULT?

Kind regards,
Petr

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Re: [LTP] [PATCH v16 2/2] futex_cmp_requeue03: Add EFAULT error coverage test

[Petr Vorel]

Hi Michael,

...
> +static struct testcase {
> +	const char *desc;
> +	futex_t **uaddr;
> +	futex_t **uaddr2;
> +	int exp_errno;
> +} testcases[] = {
> +	{
> +		.desc = "uaddr unmapped",
> +		.uaddr = &unmapped_addr,
> +		.uaddr2 = &futex_ptr,
> +		.exp_errno = EFAULT,
> +	},
> +	{
> +		.desc = "uaddr2 unmapped",
> +		.uaddr = &futex_ptr,
> +		.uaddr2 = &unmapped_addr,
> +		.exp_errno = EFAULT,
> +	},
> +	{
> +		.desc = "uaddr PROT_NONE",
> +		.uaddr = &prot_none_addr,
> +		.uaddr2 = &futex_ptr,
> +		.exp_errno = EFAULT,
> +	},
> +	{
> +		.desc = "uaddr2 PROT_NONE",
> +		.uaddr = &futex_ptr,
> +		.uaddr2 = &prot_none_addr,
> +		.exp_errno = EFAULT,
> +	},
> +};
nit: also here I'd use EFAULT directly in TST_EXP_FAIL(), but that's a minor
detail.

The rest LGTM.
Reviewed-by: Petr Vorel <pvorel@suse.cz>

Kind regards,
Petr


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