[PATCH 1/1] ucrtbase/tests: Avoid reading behind buffer in test_swprintf (ASan).

[Bernhard Übelacker]

From: Bernhard Übelacker

---
 dlls/ucrtbase/tests/printf.c | 12 +++++++++++-
 1 file changed, 11 insertions(+), 1 deletion(-)

diff --git a/dlls/ucrtbase/tests/printf.c b/dlls/ucrtbase/tests/printf.c
index 75bd7830869..ff2b274c996 100644
--- a/dlls/ucrtbase/tests/printf.c
+++ b/dlls/ucrtbase/tests/printf.c
@@ -181,10 +181,17 @@ static void test_swprintf (void)
     const wchar_t str_empty[]      = {0};
     const wchar_t *tests[] = {str_short, str_justfit, str_justfits, str_muchlonger};

-    wchar_t buffer[8];
+    struct {
+        wchar_t buffer[8];
+        wchar_t chk;
+        wchar_t term;
+    } buf;
+#define buffer buf.buffer
     char narrow[8], narrow_fmt[16];
     const int bufsiz = ARRAY_SIZE(buffer);
     unsigned int i;
+    memset(&buf, 0xcd, sizeof(buf));
+    buf.term = L'\0';

/* Legacy _snprintf style termination */
     for (i = 0; i < ARRAY_SIZE(tests); i++) {
@@ -253,6 +260,9 @@ static void test_swprintf (void)
         "Failure to swprintf a zero length string to a zero length buffer\n");
     ok (vswprintf_wrapper (0, buffer, 0, str_empty) == -1,
         "Failure to swprintf a zero length string to a zero length buffer\n");
+
+    ok (buf.chk == 0xcdcd, "buf.chk got overwritten.\n");
+#undef buffer
 }

static int WINAPIV vfprintf_wrapper(FILE *file,