execve: Move KUnit tests to tests/ subdirectory

Move the exec KUnit tests into a separate directory to avoid polluting
the local directory namespace. Additionally update MAINTAINERS for the
new files.

Reviewed-by: David Gow <davidgow@google.com>
Reviewed-by: SeongJae Park <sj@kernel.org>
Acked-by: Christian Brauner <brauner@kernel.org>
Link: https://lore.kernel.org/r/20240720170310.it.942-kees@kernel.org
Signed-off-by: Kees Cook <kees@kernel.org>

diff --git a/MAINTAINERS b/MAINTAINERS
index 8dfbe998f175f9b8df13c43de93d981359842b33..5fa7e129a59eb0cc54be854ec4715bd4941a0e91 100644 (file)
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -8220,7 +8220,8 @@ F:        Documentation/userspace-api/ELF.rst
 F:     fs/*binfmt_*.c
 F:     fs/Kconfig.binfmt
 F:     fs/exec.c
-F:     fs/exec_test.c
+F:     fs/tests/binfmt_*_kunit.c
+F:     fs/tests/exec_kunit.c
 F:     include/linux/binfmts.h
 F:     include/linux/elf.h
 F:     include/uapi/linux/binfmts.h

diff --git a/fs/binfmt_elf.c b/fs/binfmt_elf.c
index 40111451aa95118018e88efc97522b44696d673b..04e748c5955f0d148b350ddf27d30d48eaa31555 100644 (file)
--- a/fs/binfmt_elf.c
+++ b/fs/binfmt_elf.c
@@ -2152,5 +2152,5 @@ core_initcall(init_elf_binfmt);
 module_exit(exit_elf_binfmt);
 
 #ifdef CONFIG_BINFMT_ELF_KUNIT_TEST
-#include "binfmt_elf_test.c"
+#include "tests/binfmt_elf_kunit.c"
 #endif

diff --git a/fs/binfmt_elf_test.c b/fs/binfmt_elf_test.c
deleted file mode 100644 (file)
index 11d734f..0000000
--- a/fs/binfmt_elf_test.c
+++ /dev/null
@@ -1,64 +0,0 @@
-// SPDX-License-Identifier: GPL-2.0-only
-#include <kunit/test.h>
-
-static void total_mapping_size_test(struct kunit *test)
-{
-       struct elf_phdr empty[] = {
-               { .p_type = PT_LOAD, .p_vaddr = 0, .p_memsz = 0, },
-               { .p_type = PT_INTERP, .p_vaddr = 10, .p_memsz = 999999, },
-       };
-       /*
-        * readelf -lW /bin/mount | grep '^  .*0x0' | awk '{print "\t\t{ .p_type = PT_" \
-        *                              $1 ", .p_vaddr = " $3 ", .p_memsz = " $6 ", },"}'
-        */
-       struct elf_phdr mount[] = {
-               { .p_type = PT_PHDR, .p_vaddr = 0x00000040, .p_memsz = 0x0002d8, },
-               { .p_type = PT_INTERP, .p_vaddr = 0x00000318, .p_memsz = 0x00001c, },
-               { .p_type = PT_LOAD, .p_vaddr = 0x00000000, .p_memsz = 0x0033a8, },
-               { .p_type = PT_LOAD, .p_vaddr = 0x00004000, .p_memsz = 0x005c91, },
-               { .p_type = PT_LOAD, .p_vaddr = 0x0000a000, .p_memsz = 0x0022f8, },
-               { .p_type = PT_LOAD, .p_vaddr = 0x0000d330, .p_memsz = 0x000d40, },
-               { .p_type = PT_DYNAMIC, .p_vaddr = 0x0000d928, .p_memsz = 0x000200, },
-               { .p_type = PT_NOTE, .p_vaddr = 0x00000338, .p_memsz = 0x000030, },
-               { .p_type = PT_NOTE, .p_vaddr = 0x00000368, .p_memsz = 0x000044, },
-               { .p_type = PT_GNU_PROPERTY, .p_vaddr = 0x00000338, .p_memsz = 0x000030, },
-               { .p_type = PT_GNU_EH_FRAME, .p_vaddr = 0x0000b490, .p_memsz = 0x0001ec, },
-               { .p_type = PT_GNU_STACK, .p_vaddr = 0x00000000, .p_memsz = 0x000000, },
-               { .p_type = PT_GNU_RELRO, .p_vaddr = 0x0000d330, .p_memsz = 0x000cd0, },
-       };
-       size_t mount_size = 0xE070;
-       /* https://lore.kernel.org/linux-fsdevel/YfF18Dy85mCntXrx@fractal.localdomain */
-       struct elf_phdr unordered[] = {
-               { .p_type = PT_LOAD, .p_vaddr = 0x00000000, .p_memsz = 0x0033a8, },
-               { .p_type = PT_LOAD, .p_vaddr = 0x0000d330, .p_memsz = 0x000d40, },
-               { .p_type = PT_LOAD, .p_vaddr = 0x00004000, .p_memsz = 0x005c91, },
-               { .p_type = PT_LOAD, .p_vaddr = 0x0000a000, .p_memsz = 0x0022f8, },
-       };
-
-       /* No headers, no size. */
-       KUNIT_EXPECT_EQ(test, total_mapping_size(NULL, 0), 0);
-       KUNIT_EXPECT_EQ(test, total_mapping_size(empty, 0), 0);
-       /* Empty headers, no size. */
-       KUNIT_EXPECT_EQ(test, total_mapping_size(empty, 1), 0);
-       /* No PT_LOAD headers, no size. */
-       KUNIT_EXPECT_EQ(test, total_mapping_size(&empty[1], 1), 0);
-       /* Empty PT_LOAD and non-PT_LOAD headers, no size. */
-       KUNIT_EXPECT_EQ(test, total_mapping_size(empty, 2), 0);
-
-       /* Normal set of PT_LOADS, and expected size. */
-       KUNIT_EXPECT_EQ(test, total_mapping_size(mount, ARRAY_SIZE(mount)), mount_size);
-       /* Unordered PT_LOADs result in same size. */
-       KUNIT_EXPECT_EQ(test, total_mapping_size(unordered, ARRAY_SIZE(unordered)), mount_size);
-}
-
-static struct kunit_case binfmt_elf_test_cases[] = {
-       KUNIT_CASE(total_mapping_size_test),
-       {},
-};
-
-static struct kunit_suite binfmt_elf_test_suite = {
-       .name = KBUILD_MODNAME,
-       .test_cases = binfmt_elf_test_cases,
-};
-
-kunit_test_suite(binfmt_elf_test_suite);

diff --git a/fs/exec.c b/fs/exec.c
index 5b580ff8d955660b26f7862074c18b013ef1971b..32d6537ece07dea54f08ba4c06b1cab87445d25d 100644 (file)
--- a/fs/exec.c
+++ b/fs/exec.c
@@ -2244,5 +2244,5 @@ fs_initcall(init_fs_exec_sysctls);
 #endif /* CONFIG_SYSCTL */
 
 #ifdef CONFIG_EXEC_KUNIT_TEST
-#include "exec_test.c"
+#include "tests/exec_kunit.c"
 #endif

diff --git a/fs/exec_test.c b/fs/exec_test.c
deleted file mode 100644 (file)
index 7c77d03..0000000
--- a/fs/exec_test.c
+++ /dev/null
@@ -1,141 +0,0 @@
-// SPDX-License-Identifier: GPL-2.0-only
-#include <kunit/test.h>
-
-struct bprm_stack_limits_result {
-       struct linux_binprm bprm;
-       int expected_rc;
-       unsigned long expected_argmin;
-};
-
-static const struct bprm_stack_limits_result bprm_stack_limits_results[] = {
-       /* Negative argc/envc counts produce -E2BIG */
-       { { .p = ULONG_MAX, .rlim_stack.rlim_cur = ULONG_MAX,
-           .argc = INT_MIN, .envc = INT_MIN }, .expected_rc = -E2BIG },
-       { { .p = ULONG_MAX, .rlim_stack.rlim_cur = ULONG_MAX,
-           .argc = 5, .envc = -1 }, .expected_rc = -E2BIG },
-       { { .p = ULONG_MAX, .rlim_stack.rlim_cur = ULONG_MAX,
-           .argc = -1, .envc = 10 }, .expected_rc = -E2BIG },
-       /* The max value of argc or envc is MAX_ARG_STRINGS. */
-       { { .p = ULONG_MAX, .rlim_stack.rlim_cur = ULONG_MAX,
-           .argc = INT_MAX, .envc = INT_MAX }, .expected_rc = -E2BIG },
-       { { .p = ULONG_MAX, .rlim_stack.rlim_cur = ULONG_MAX,
-           .argc = MAX_ARG_STRINGS, .envc = MAX_ARG_STRINGS }, .expected_rc = -E2BIG },
-       { { .p = ULONG_MAX, .rlim_stack.rlim_cur = ULONG_MAX,
-           .argc = 0, .envc = MAX_ARG_STRINGS }, .expected_rc = -E2BIG },
-       { { .p = ULONG_MAX, .rlim_stack.rlim_cur = ULONG_MAX,
-           .argc = MAX_ARG_STRINGS, .envc = 0 }, .expected_rc = -E2BIG },
-       /*
-        * On 32-bit system these argc and envc counts, while likely impossible
-        * to represent within the associated TASK_SIZE, could overflow the
-        * limit calculation, and bypass the ptr_size <= limit check.
-        */
-       { { .p = ULONG_MAX, .rlim_stack.rlim_cur = ULONG_MAX,
-           .argc = 0x20000001, .envc = 0x20000001 }, .expected_rc = -E2BIG },
-#ifdef CONFIG_MMU
-       /* Make sure a pathological bprm->p doesn't cause an overflow. */
-       { { .p = sizeof(void *), .rlim_stack.rlim_cur = ULONG_MAX,
-           .argc = 10, .envc = 10 }, .expected_rc = -E2BIG },
-#endif
-       /*
-        * 0 rlim_stack will get raised to ARG_MAX. With 1 string pointer,
-        * we should see p - ARG_MAX + sizeof(void *).
-        */
-       { { .p = ULONG_MAX, .rlim_stack.rlim_cur = 0,
-           .argc = 1, .envc = 0 }, .expected_argmin = ULONG_MAX - ARG_MAX + sizeof(void *)},
-       /* Validate that argc is always raised to a minimum of 1. */
-       { { .p = ULONG_MAX, .rlim_stack.rlim_cur = 0,
-           .argc = 0, .envc = 0 }, .expected_argmin = ULONG_MAX - ARG_MAX + sizeof(void *)},
-       /*
-        * 0 rlim_stack will get raised to ARG_MAX. With pointers filling ARG_MAX,
-        * we should see -E2BIG. (Note argc is always raised to at least 1.)
-        */
-       { { .p = ULONG_MAX, .rlim_stack.rlim_cur = 0,
-           .argc = ARG_MAX / sizeof(void *), .envc = 0 }, .expected_rc = -E2BIG },
-       { { .p = ULONG_MAX, .rlim_stack.rlim_cur = 0,
-           .argc = 0, .envc = ARG_MAX / sizeof(void *) - 1 }, .expected_rc = -E2BIG },
-       { { .p = ULONG_MAX, .rlim_stack.rlim_cur = 0,
-           .argc = ARG_MAX / sizeof(void *) + 1, .envc = 0 }, .expected_rc = -E2BIG },
-       { { .p = ULONG_MAX, .rlim_stack.rlim_cur = 0,
-           .argc = 0, .envc = ARG_MAX / sizeof(void *) }, .expected_rc = -E2BIG },
-       /* And with one less, we see space for exactly 1 pointer. */
-       { { .p = ULONG_MAX, .rlim_stack.rlim_cur = 0,
-           .argc = (ARG_MAX / sizeof(void *)) - 1, .envc = 0 },
-         .expected_argmin = ULONG_MAX - sizeof(void *) },
-       { { .p = ULONG_MAX, .rlim_stack.rlim_cur = 0,
-           .argc = 0, .envc = (ARG_MAX / sizeof(void *)) - 2, },
-         .expected_argmin = ULONG_MAX - sizeof(void *) },
-       /* If we raise rlim_stack / 4 to exactly ARG_MAX, nothing changes. */
-       { { .p = ULONG_MAX, .rlim_stack.rlim_cur = ARG_MAX * 4,
-           .argc = ARG_MAX / sizeof(void *), .envc = 0 }, .expected_rc = -E2BIG },
-       { { .p = ULONG_MAX, .rlim_stack.rlim_cur = ARG_MAX * 4,
-           .argc = 0, .envc = ARG_MAX / sizeof(void *) - 1 }, .expected_rc = -E2BIG },
-       { { .p = ULONG_MAX, .rlim_stack.rlim_cur = ARG_MAX * 4,
-           .argc = ARG_MAX / sizeof(void *) + 1, .envc = 0 }, .expected_rc = -E2BIG },
-       { { .p = ULONG_MAX, .rlim_stack.rlim_cur = ARG_MAX * 4,
-           .argc = 0, .envc = ARG_MAX / sizeof(void *) }, .expected_rc = -E2BIG },
-       { { .p = ULONG_MAX, .rlim_stack.rlim_cur = ARG_MAX * 4,
-           .argc = (ARG_MAX / sizeof(void *)) - 1, .envc = 0 },
-         .expected_argmin = ULONG_MAX - sizeof(void *) },
-       { { .p = ULONG_MAX, .rlim_stack.rlim_cur = ARG_MAX * 4,
-           .argc = 0, .envc = (ARG_MAX / sizeof(void *)) - 2, },
-         .expected_argmin = ULONG_MAX - sizeof(void *) },
-       /* But raising it another pointer * 4 will provide space for 1 more pointer. */
-       { { .p = ULONG_MAX, .rlim_stack.rlim_cur = (ARG_MAX + sizeof(void *)) * 4,
-           .argc = ARG_MAX / sizeof(void *), .envc = 0 },
-         .expected_argmin = ULONG_MAX - sizeof(void *) },
-       { { .p = ULONG_MAX, .rlim_stack.rlim_cur = (ARG_MAX + sizeof(void *)) * 4,
-           .argc = 0, .envc = ARG_MAX / sizeof(void *) - 1 },
-         .expected_argmin = ULONG_MAX - sizeof(void *) },
-       /* Raising rlim_stack / 4 to _STK_LIM / 4 * 3 will see more space. */
-       { { .p = ULONG_MAX, .rlim_stack.rlim_cur = 4 * (_STK_LIM / 4 * 3),
-           .argc = 0, .envc = 0 },
-         .expected_argmin = ULONG_MAX - (_STK_LIM / 4 * 3) + sizeof(void *) },
-       { { .p = ULONG_MAX, .rlim_stack.rlim_cur = 4 * (_STK_LIM / 4 * 3),
-           .argc = 0, .envc = 0 },
-         .expected_argmin = ULONG_MAX - (_STK_LIM / 4 * 3) + sizeof(void *) },
-       /* But raising it any further will see no increase. */
-       { { .p = ULONG_MAX, .rlim_stack.rlim_cur = 4 * (_STK_LIM / 4 * 3 + sizeof(void *)),
-           .argc = 0, .envc = 0 },
-         .expected_argmin = ULONG_MAX - (_STK_LIM / 4 * 3) + sizeof(void *) },
-       { { .p = ULONG_MAX, .rlim_stack.rlim_cur = 4 * (_STK_LIM / 4 *  + sizeof(void *)),
-           .argc = 0, .envc = 0 },
-         .expected_argmin = ULONG_MAX - (_STK_LIM / 4 * 3) + sizeof(void *) },
-       { { .p = ULONG_MAX, .rlim_stack.rlim_cur = 4 * _STK_LIM,
-           .argc = 0, .envc = 0 },
-         .expected_argmin = ULONG_MAX - (_STK_LIM / 4 * 3) + sizeof(void *) },
-       { { .p = ULONG_MAX, .rlim_stack.rlim_cur = 4 * _STK_LIM,
-           .argc = 0, .envc = 0 },
-         .expected_argmin = ULONG_MAX - (_STK_LIM / 4 * 3) + sizeof(void *) },
-};
-
-static void exec_test_bprm_stack_limits(struct kunit *test)
-{
-       /* Double-check the constants. */
-       KUNIT_EXPECT_EQ(test, _STK_LIM, SZ_8M);
-       KUNIT_EXPECT_EQ(test, ARG_MAX, 32 * SZ_4K);
-       KUNIT_EXPECT_EQ(test, MAX_ARG_STRINGS, 0x7FFFFFFF);
-
-       for (int i = 0; i < ARRAY_SIZE(bprm_stack_limits_results); i++) {
-               const struct bprm_stack_limits_result *result = &bprm_stack_limits_results[i];
-               struct linux_binprm bprm = result->bprm;
-               int rc;
-
-               rc = bprm_stack_limits(&bprm);
-               KUNIT_EXPECT_EQ_MSG(test, rc, result->expected_rc, "on loop %d", i);
-#ifdef CONFIG_MMU
-               KUNIT_EXPECT_EQ_MSG(test, bprm.argmin, result->expected_argmin, "on loop %d", i);
-#endif
-       }
-}
-
-static struct kunit_case exec_test_cases[] = {
-       KUNIT_CASE(exec_test_bprm_stack_limits),
-       {},
-};
-
-static struct kunit_suite exec_test_suite = {
-       .name = "exec",
-       .test_cases = exec_test_cases,
-};
-
-kunit_test_suite(exec_test_suite);

diff --git a/fs/tests/binfmt_elf_kunit.c b/fs/tests/binfmt_elf_kunit.c
new file mode 100644 (file)
index 0000000..11d734f
--- /dev/null
+++ b/fs/tests/binfmt_elf_kunit.c
@@ -0,0 +1,64 @@
+// SPDX-License-Identifier: GPL-2.0-only
+#include <kunit/test.h>
+
+static void total_mapping_size_test(struct kunit *test)
+{
+       struct elf_phdr empty[] = {
+               { .p_type = PT_LOAD, .p_vaddr = 0, .p_memsz = 0, },
+               { .p_type = PT_INTERP, .p_vaddr = 10, .p_memsz = 999999, },
+       };
+       /*
+        * readelf -lW /bin/mount | grep '^  .*0x0' | awk '{print "\t\t{ .p_type = PT_" \
+        *                              $1 ", .p_vaddr = " $3 ", .p_memsz = " $6 ", },"}'
+        */
+       struct elf_phdr mount[] = {
+               { .p_type = PT_PHDR, .p_vaddr = 0x00000040, .p_memsz = 0x0002d8, },
+               { .p_type = PT_INTERP, .p_vaddr = 0x00000318, .p_memsz = 0x00001c, },
+               { .p_type = PT_LOAD, .p_vaddr = 0x00000000, .p_memsz = 0x0033a8, },
+               { .p_type = PT_LOAD, .p_vaddr = 0x00004000, .p_memsz = 0x005c91, },
+               { .p_type = PT_LOAD, .p_vaddr = 0x0000a000, .p_memsz = 0x0022f8, },
+               { .p_type = PT_LOAD, .p_vaddr = 0x0000d330, .p_memsz = 0x000d40, },
+               { .p_type = PT_DYNAMIC, .p_vaddr = 0x0000d928, .p_memsz = 0x000200, },
+               { .p_type = PT_NOTE, .p_vaddr = 0x00000338, .p_memsz = 0x000030, },
+               { .p_type = PT_NOTE, .p_vaddr = 0x00000368, .p_memsz = 0x000044, },
+               { .p_type = PT_GNU_PROPERTY, .p_vaddr = 0x00000338, .p_memsz = 0x000030, },
+               { .p_type = PT_GNU_EH_FRAME, .p_vaddr = 0x0000b490, .p_memsz = 0x0001ec, },
+               { .p_type = PT_GNU_STACK, .p_vaddr = 0x00000000, .p_memsz = 0x000000, },
+               { .p_type = PT_GNU_RELRO, .p_vaddr = 0x0000d330, .p_memsz = 0x000cd0, },
+       };
+       size_t mount_size = 0xE070;
+       /* https://lore.kernel.org/linux-fsdevel/YfF18Dy85mCntXrx@fractal.localdomain */
+       struct elf_phdr unordered[] = {
+               { .p_type = PT_LOAD, .p_vaddr = 0x00000000, .p_memsz = 0x0033a8, },
+               { .p_type = PT_LOAD, .p_vaddr = 0x0000d330, .p_memsz = 0x000d40, },
+               { .p_type = PT_LOAD, .p_vaddr = 0x00004000, .p_memsz = 0x005c91, },
+               { .p_type = PT_LOAD, .p_vaddr = 0x0000a000, .p_memsz = 0x0022f8, },
+       };
+
+       /* No headers, no size. */
+       KUNIT_EXPECT_EQ(test, total_mapping_size(NULL, 0), 0);
+       KUNIT_EXPECT_EQ(test, total_mapping_size(empty, 0), 0);
+       /* Empty headers, no size. */
+       KUNIT_EXPECT_EQ(test, total_mapping_size(empty, 1), 0);
+       /* No PT_LOAD headers, no size. */
+       KUNIT_EXPECT_EQ(test, total_mapping_size(&empty[1], 1), 0);
+       /* Empty PT_LOAD and non-PT_LOAD headers, no size. */
+       KUNIT_EXPECT_EQ(test, total_mapping_size(empty, 2), 0);
+
+       /* Normal set of PT_LOADS, and expected size. */
+       KUNIT_EXPECT_EQ(test, total_mapping_size(mount, ARRAY_SIZE(mount)), mount_size);
+       /* Unordered PT_LOADs result in same size. */
+       KUNIT_EXPECT_EQ(test, total_mapping_size(unordered, ARRAY_SIZE(unordered)), mount_size);
+}
+
+static struct kunit_case binfmt_elf_test_cases[] = {
+       KUNIT_CASE(total_mapping_size_test),
+       {},
+};
+
+static struct kunit_suite binfmt_elf_test_suite = {
+       .name = KBUILD_MODNAME,
+       .test_cases = binfmt_elf_test_cases,
+};
+
+kunit_test_suite(binfmt_elf_test_suite);

diff --git a/fs/tests/exec_kunit.c b/fs/tests/exec_kunit.c
new file mode 100644 (file)
index 0000000..7c77d03
--- /dev/null
+++ b/fs/tests/exec_kunit.c
@@ -0,0 +1,141 @@
+// SPDX-License-Identifier: GPL-2.0-only
+#include <kunit/test.h>
+
+struct bprm_stack_limits_result {
+       struct linux_binprm bprm;
+       int expected_rc;
+       unsigned long expected_argmin;
+};
+
+static const struct bprm_stack_limits_result bprm_stack_limits_results[] = {
+       /* Negative argc/envc counts produce -E2BIG */
+       { { .p = ULONG_MAX, .rlim_stack.rlim_cur = ULONG_MAX,
+           .argc = INT_MIN, .envc = INT_MIN }, .expected_rc = -E2BIG },
+       { { .p = ULONG_MAX, .rlim_stack.rlim_cur = ULONG_MAX,
+           .argc = 5, .envc = -1 }, .expected_rc = -E2BIG },
+       { { .p = ULONG_MAX, .rlim_stack.rlim_cur = ULONG_MAX,
+           .argc = -1, .envc = 10 }, .expected_rc = -E2BIG },
+       /* The max value of argc or envc is MAX_ARG_STRINGS. */
+       { { .p = ULONG_MAX, .rlim_stack.rlim_cur = ULONG_MAX,
+           .argc = INT_MAX, .envc = INT_MAX }, .expected_rc = -E2BIG },
+       { { .p = ULONG_MAX, .rlim_stack.rlim_cur = ULONG_MAX,
+           .argc = MAX_ARG_STRINGS, .envc = MAX_ARG_STRINGS }, .expected_rc = -E2BIG },
+       { { .p = ULONG_MAX, .rlim_stack.rlim_cur = ULONG_MAX,
+           .argc = 0, .envc = MAX_ARG_STRINGS }, .expected_rc = -E2BIG },
+       { { .p = ULONG_MAX, .rlim_stack.rlim_cur = ULONG_MAX,
+           .argc = MAX_ARG_STRINGS, .envc = 0 }, .expected_rc = -E2BIG },
+       /*
+        * On 32-bit system these argc and envc counts, while likely impossible
+        * to represent within the associated TASK_SIZE, could overflow the
+        * limit calculation, and bypass the ptr_size <= limit check.
+        */
+       { { .p = ULONG_MAX, .rlim_stack.rlim_cur = ULONG_MAX,
+           .argc = 0x20000001, .envc = 0x20000001 }, .expected_rc = -E2BIG },
+#ifdef CONFIG_MMU
+       /* Make sure a pathological bprm->p doesn't cause an overflow. */
+       { { .p = sizeof(void *), .rlim_stack.rlim_cur = ULONG_MAX,
+           .argc = 10, .envc = 10 }, .expected_rc = -E2BIG },
+#endif
+       /*
+        * 0 rlim_stack will get raised to ARG_MAX. With 1 string pointer,
+        * we should see p - ARG_MAX + sizeof(void *).
+        */
+       { { .p = ULONG_MAX, .rlim_stack.rlim_cur = 0,
+           .argc = 1, .envc = 0 }, .expected_argmin = ULONG_MAX - ARG_MAX + sizeof(void *)},
+       /* Validate that argc is always raised to a minimum of 1. */
+       { { .p = ULONG_MAX, .rlim_stack.rlim_cur = 0,
+           .argc = 0, .envc = 0 }, .expected_argmin = ULONG_MAX - ARG_MAX + sizeof(void *)},
+       /*
+        * 0 rlim_stack will get raised to ARG_MAX. With pointers filling ARG_MAX,
+        * we should see -E2BIG. (Note argc is always raised to at least 1.)
+        */
+       { { .p = ULONG_MAX, .rlim_stack.rlim_cur = 0,
+           .argc = ARG_MAX / sizeof(void *), .envc = 0 }, .expected_rc = -E2BIG },
+       { { .p = ULONG_MAX, .rlim_stack.rlim_cur = 0,
+           .argc = 0, .envc = ARG_MAX / sizeof(void *) - 1 }, .expected_rc = -E2BIG },
+       { { .p = ULONG_MAX, .rlim_stack.rlim_cur = 0,
+           .argc = ARG_MAX / sizeof(void *) + 1, .envc = 0 }, .expected_rc = -E2BIG },
+       { { .p = ULONG_MAX, .rlim_stack.rlim_cur = 0,
+           .argc = 0, .envc = ARG_MAX / sizeof(void *) }, .expected_rc = -E2BIG },
+       /* And with one less, we see space for exactly 1 pointer. */
+       { { .p = ULONG_MAX, .rlim_stack.rlim_cur = 0,
+           .argc = (ARG_MAX / sizeof(void *)) - 1, .envc = 0 },
+         .expected_argmin = ULONG_MAX - sizeof(void *) },
+       { { .p = ULONG_MAX, .rlim_stack.rlim_cur = 0,
+           .argc = 0, .envc = (ARG_MAX / sizeof(void *)) - 2, },
+         .expected_argmin = ULONG_MAX - sizeof(void *) },
+       /* If we raise rlim_stack / 4 to exactly ARG_MAX, nothing changes. */
+       { { .p = ULONG_MAX, .rlim_stack.rlim_cur = ARG_MAX * 4,
+           .argc = ARG_MAX / sizeof(void *), .envc = 0 }, .expected_rc = -E2BIG },
+       { { .p = ULONG_MAX, .rlim_stack.rlim_cur = ARG_MAX * 4,
+           .argc = 0, .envc = ARG_MAX / sizeof(void *) - 1 }, .expected_rc = -E2BIG },
+       { { .p = ULONG_MAX, .rlim_stack.rlim_cur = ARG_MAX * 4,
+           .argc = ARG_MAX / sizeof(void *) + 1, .envc = 0 }, .expected_rc = -E2BIG },
+       { { .p = ULONG_MAX, .rlim_stack.rlim_cur = ARG_MAX * 4,
+           .argc = 0, .envc = ARG_MAX / sizeof(void *) }, .expected_rc = -E2BIG },
+       { { .p = ULONG_MAX, .rlim_stack.rlim_cur = ARG_MAX * 4,
+           .argc = (ARG_MAX / sizeof(void *)) - 1, .envc = 0 },
+         .expected_argmin = ULONG_MAX - sizeof(void *) },
+       { { .p = ULONG_MAX, .rlim_stack.rlim_cur = ARG_MAX * 4,
+           .argc = 0, .envc = (ARG_MAX / sizeof(void *)) - 2, },
+         .expected_argmin = ULONG_MAX - sizeof(void *) },
+       /* But raising it another pointer * 4 will provide space for 1 more pointer. */
+       { { .p = ULONG_MAX, .rlim_stack.rlim_cur = (ARG_MAX + sizeof(void *)) * 4,
+           .argc = ARG_MAX / sizeof(void *), .envc = 0 },
+         .expected_argmin = ULONG_MAX - sizeof(void *) },
+       { { .p = ULONG_MAX, .rlim_stack.rlim_cur = (ARG_MAX + sizeof(void *)) * 4,
+           .argc = 0, .envc = ARG_MAX / sizeof(void *) - 1 },
+         .expected_argmin = ULONG_MAX - sizeof(void *) },
+       /* Raising rlim_stack / 4 to _STK_LIM / 4 * 3 will see more space. */
+       { { .p = ULONG_MAX, .rlim_stack.rlim_cur = 4 * (_STK_LIM / 4 * 3),
+           .argc = 0, .envc = 0 },
+         .expected_argmin = ULONG_MAX - (_STK_LIM / 4 * 3) + sizeof(void *) },
+       { { .p = ULONG_MAX, .rlim_stack.rlim_cur = 4 * (_STK_LIM / 4 * 3),
+           .argc = 0, .envc = 0 },
+         .expected_argmin = ULONG_MAX - (_STK_LIM / 4 * 3) + sizeof(void *) },
+       /* But raising it any further will see no increase. */
+       { { .p = ULONG_MAX, .rlim_stack.rlim_cur = 4 * (_STK_LIM / 4 * 3 + sizeof(void *)),
+           .argc = 0, .envc = 0 },
+         .expected_argmin = ULONG_MAX - (_STK_LIM / 4 * 3) + sizeof(void *) },
+       { { .p = ULONG_MAX, .rlim_stack.rlim_cur = 4 * (_STK_LIM / 4 *  + sizeof(void *)),
+           .argc = 0, .envc = 0 },
+         .expected_argmin = ULONG_MAX - (_STK_LIM / 4 * 3) + sizeof(void *) },
+       { { .p = ULONG_MAX, .rlim_stack.rlim_cur = 4 * _STK_LIM,
+           .argc = 0, .envc = 0 },
+         .expected_argmin = ULONG_MAX - (_STK_LIM / 4 * 3) + sizeof(void *) },
+       { { .p = ULONG_MAX, .rlim_stack.rlim_cur = 4 * _STK_LIM,
+           .argc = 0, .envc = 0 },
+         .expected_argmin = ULONG_MAX - (_STK_LIM / 4 * 3) + sizeof(void *) },
+};
+
+static void exec_test_bprm_stack_limits(struct kunit *test)
+{
+       /* Double-check the constants. */
+       KUNIT_EXPECT_EQ(test, _STK_LIM, SZ_8M);
+       KUNIT_EXPECT_EQ(test, ARG_MAX, 32 * SZ_4K);
+       KUNIT_EXPECT_EQ(test, MAX_ARG_STRINGS, 0x7FFFFFFF);
+
+       for (int i = 0; i < ARRAY_SIZE(bprm_stack_limits_results); i++) {
+               const struct bprm_stack_limits_result *result = &bprm_stack_limits_results[i];
+               struct linux_binprm bprm = result->bprm;
+               int rc;
+
+               rc = bprm_stack_limits(&bprm);
+               KUNIT_EXPECT_EQ_MSG(test, rc, result->expected_rc, "on loop %d", i);
+#ifdef CONFIG_MMU
+               KUNIT_EXPECT_EQ_MSG(test, bprm.argmin, result->expected_argmin, "on loop %d", i);
+#endif
+       }
+}
+
+static struct kunit_case exec_test_cases[] = {
+       KUNIT_CASE(exec_test_bprm_stack_limits),
+       {},
+};
+
+static struct kunit_suite exec_test_suite = {
+       .name = "exec",
+       .test_cases = exec_test_cases,
+};
+
+kunit_test_suite(exec_test_suite);