Add KUnit coverage for the zero-size allocation contract, including ZERO_SIZE_PTR alignment and exact ZERO_OR_NULL_PTR() matching.
Assisted-by: Claude:claude-fable-5 Signed-off-by: Karl Mehltretter <[email protected]> --- lib/tests/slub_kunit.c | 43 ++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 43 insertions(+) diff --git a/lib/tests/slub_kunit.c b/lib/tests/slub_kunit.c index fa6d31dbca166..a02fc6b401e3e 100644 --- a/lib/tests/slub_kunit.c +++ b/lib/tests/slub_kunit.c @@ -380,6 +380,48 @@ static void test_kmalloc_kfree_nolock(struct kunit *test) } #endif +static void test_zero_size_alloc(struct kunit *test) +{ + unsigned long zsp = (unsigned long)ZERO_SIZE_PTR; + void *p, *r; + + static_assert((unsigned long)ZERO_SIZE_PTR % ARCH_KMALLOC_MINALIGN == 0); + + p = kmalloc(0, GFP_KERNEL); + KUNIT_EXPECT_PTR_EQ(test, p, ZERO_SIZE_PTR); + KUNIT_EXPECT_EQ(test, ksize(p), 0); + kfree(p); + + KUNIT_EXPECT_PTR_EQ(test, kzalloc(0, GFP_KERNEL), ZERO_SIZE_PTR); + KUNIT_EXPECT_PTR_EQ(test, kmalloc_array(0, 8, GFP_KERNEL), ZERO_SIZE_PTR); + KUNIT_EXPECT_PTR_EQ(test, kcalloc(4, 0, GFP_KERNEL), ZERO_SIZE_PTR); + + p = kvmalloc(0, GFP_KERNEL); + KUNIT_EXPECT_PTR_EQ(test, p, ZERO_SIZE_PTR); + kvfree(p); + + p = krealloc(NULL, 0, GFP_KERNEL); + KUNIT_EXPECT_PTR_EQ(test, p, ZERO_SIZE_PTR); + r = krealloc(p, 64, GFP_KERNEL); + KUNIT_EXPECT_FALSE(test, ZERO_OR_NULL_PTR(r)); + p = krealloc(r, 0, GFP_KERNEL); + KUNIT_EXPECT_PTR_EQ(test, p, ZERO_SIZE_PTR); + kfree(p); + + /* Only NULL and the zero-size sentinel match. */ + KUNIT_EXPECT_TRUE(test, ZERO_OR_NULL_PTR(NULL)); + KUNIT_EXPECT_TRUE(test, ZERO_OR_NULL_PTR(ZERO_SIZE_PTR)); + KUNIT_EXPECT_FALSE(test, ZERO_OR_NULL_PTR((void *)1)); + KUNIT_EXPECT_FALSE(test, ZERO_OR_NULL_PTR((void *)(zsp - 1))); + KUNIT_EXPECT_FALSE(test, ZERO_OR_NULL_PTR((void *)(zsp + 1))); + KUNIT_EXPECT_FALSE(test, ZERO_OR_NULL_PTR((void *)(zsp * 2))); + + /* freeing the sentinel must stay a no-op */ + kfree(ZERO_SIZE_PTR); + kfree_sensitive(ZERO_SIZE_PTR); + kvfree(ZERO_SIZE_PTR); +} + static int test_init(struct kunit *test) { slab_errors = 0; @@ -404,6 +446,7 @@ static struct kunit_case test_cases[] = { KUNIT_CASE(test_kfree_rcu_wq_destroy), KUNIT_CASE(test_leak_destroy), KUNIT_CASE(test_krealloc_redzone_zeroing), + KUNIT_CASE(test_zero_size_alloc), #ifdef CONFIG_PERF_EVENTS KUNIT_CASE_SLOW(test_kmalloc_kfree_nolock), #endif -- 2.53.0
