Add a KUnit test for strlen() to verify correctness across different string lengths and memory alignments. Use vmalloc() to place the NUL character at the page boundary to ensure over-reads are detected.
Suggested-by: Kees Cook <[email protected]> Signed-off-by: Feng Jiang <[email protected]> --- lib/tests/string_kunit.c | 29 +++++++++++++++++++++++++++++ 1 file changed, 29 insertions(+) diff --git a/lib/tests/string_kunit.c b/lib/tests/string_kunit.c index f9a8e557ba77..335f2e6c2ed6 100644 --- a/lib/tests/string_kunit.c +++ b/lib/tests/string_kunit.c @@ -10,6 +10,7 @@ #include <linux/printk.h> #include <linux/slab.h> #include <linux/string.h> +#include <linux/vmalloc.h> #define STRCMP_LARGE_BUF_LEN 2048 #define STRCMP_CHANGE_POINT 1337 @@ -17,6 +18,9 @@ #define STRCMP_TEST_EXPECT_LOWER(test, fn, ...) KUNIT_EXPECT_LT(test, fn(__VA_ARGS__), 0) #define STRCMP_TEST_EXPECT_GREATER(test, fn, ...) KUNIT_EXPECT_GT(test, fn(__VA_ARGS__), 0) +#define STRING_TEST_MAX_LEN 128 +#define STRING_TEST_MAX_OFFSET 16 + static void string_test_memset16(struct kunit *test) { unsigned i, j, k; @@ -104,6 +108,30 @@ static void string_test_memset64(struct kunit *test) } } +static void string_test_strlen(struct kunit *test) +{ + size_t buf_size; + char *buf, *s; + + buf_size = PAGE_ALIGN(STRING_TEST_MAX_LEN + STRING_TEST_MAX_OFFSET + 1); + buf = vmalloc(buf_size); + KUNIT_ASSERT_NOT_ERR_OR_NULL(test, buf); + + memset(buf, 'A', buf_size); + + for (size_t offset = 0; offset < STRING_TEST_MAX_OFFSET; offset++) { + for (size_t len = 0; len <= STRING_TEST_MAX_LEN; len++) { + s = buf + buf_size - 1 - offset - len; + s[len] = '\0'; + KUNIT_EXPECT_EQ_MSG(test, strlen(s), len, + "offset:%zu len:%zu", offset, len); + s[len] = 'A'; + } + } + + vfree(buf); +} + static void string_test_strchr(struct kunit *test) { const char *test_string = "abcdefghijkl"; @@ -618,6 +646,7 @@ static struct kunit_case string_test_cases[] = { KUNIT_CASE(string_test_memset16), KUNIT_CASE(string_test_memset32), KUNIT_CASE(string_test_memset64), + KUNIT_CASE(string_test_strlen), KUNIT_CASE(string_test_strchr), KUNIT_CASE(string_test_strnchr), KUNIT_CASE(string_test_strspn), -- 2.25.1
