stdio: Add tests for printf multibyte convertion leak [BZ#25691]

Checked on x86_64-linux-gnu and i686-linux-gnu.

(cherry picked from commit 910a835dc9)

stdio-common/Makefile

@@ -66,6 +66,7 @@ tests := tstscanf test_rdwr test-popen tstgetln test-fseek \
 	 tst-scanf-round \
 	 tst-renameat2 tst-bz11319 tst-bz11319-fortify2 \
 	 scanf14a scanf16a \
+	 tst-printf-bz25691
 
 
 test-srcs = tst-unbputc tst-printf tst-printfsz-islongdouble
@@ -75,10 +76,12 @@ tests-special += $(objpfx)tst-unbputc.out $(objpfx)tst-printf.out \
 		 $(objpfx)tst-printf-bz18872-mem.out \
 		 $(objpfx)tst-setvbuf1-cmp.out \
 		 $(objpfx)tst-vfprintf-width-prec-mem.out \
-		 $(objpfx)tst-printfsz-islongdouble.out
+		 $(objpfx)tst-printfsz-islongdouble.out \
+		 $(objpfx)tst-printf-bz25691-mem.out
 generated += tst-printf-bz18872.c tst-printf-bz18872.mtrace \
 	     tst-printf-bz18872-mem.out \
-	     tst-vfprintf-width-prec.mtrace tst-vfprintf-width-prec-mem.out
+	     tst-vfprintf-width-prec.mtrace tst-vfprintf-width-prec-mem.out \
+	     tst-printf-bz25691.mtrace tst-printf-bz25691-mem.out
 endif
 
 include ../Rules
@@ -100,6 +103,8 @@ endif
 tst-printf-bz18872-ENV = MALLOC_TRACE=$(objpfx)tst-printf-bz18872.mtrace
 tst-vfprintf-width-prec-ENV = \
   MALLOC_TRACE=$(objpfx)tst-vfprintf-width-prec.mtrace
+tst-printf-bz25691-ENV = \
+  MALLOC_TRACE=$(objpfx)tst-printf-bz25691.mtrace
 
 $(objpfx)tst-unbputc.out: tst-unbputc.sh $(objpfx)tst-unbputc
 	$(SHELL) $< $(common-objpfx) '$(test-program-prefix)' > $@; \

stdio-common/tst-printf-bz25691.c

@@ -0,0 +1,108 @@
+/* Test for memory leak with large width (BZ#25691).
+   Copyright (C) 2020 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <https://www.gnu.org/licenses/>.  */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <wchar.h>
+#include <stdint.h>
+#include <locale.h>
+
+#include <mcheck.h>
+#include <support/check.h>
+#include <support/support.h>
+
+static int
+do_test (void)
+{
+  mtrace ();
+
+  /* For 's' conversion specifier with 'l' modifier the array must be
+     converted to multibyte characters up to the precision specific
+     value.  */
+  {
+    /* The input size value is to force a heap allocation on temporary
+       buffer (in the old implementation).  */
+    const size_t winputsize = 64 * 1024 + 1;
+    wchar_t *winput = xmalloc (winputsize * sizeof (wchar_t));
+    wmemset (winput, L'a', winputsize - 1);
+    winput[winputsize - 1] = L'\0';
+
+    char result[9];
+    const char expected[] = "aaaaaaaa";
+    int ret;
+
+    ret = snprintf (result, sizeof (result), "%.65537ls", winput);
+    TEST_COMPARE (ret, winputsize - 1);
+    TEST_COMPARE_BLOB (result, sizeof (result), expected, sizeof (expected));
+
+    ret = snprintf (result, sizeof (result), "%ls", winput);
+    TEST_COMPARE (ret, winputsize - 1);
+    TEST_COMPARE_BLOB (result, sizeof (result), expected, sizeof (expected));
+
+    free (winput);
+  }
+
+  /* For 's' converstion specifier the array is interpreted as a multibyte
+     character sequence and converted to wide characters up to the precision
+     specific value.  */
+  {
+    /* The input size value is to force a heap allocation on temporary
+       buffer (in the old implementation).  */
+    const size_t mbssize = 32 * 1024;
+    char *mbs = xmalloc (mbssize);
+    memset (mbs, 'a', mbssize - 1);
+    mbs[mbssize - 1] = '\0';
+
+    const size_t expectedsize = 32 * 1024;
+    wchar_t *expected = xmalloc (expectedsize * sizeof (wchar_t));
+    wmemset (expected, L'a', expectedsize - 1);
+    expected[expectedsize-1] = L'\0';
+
+    const size_t resultsize = mbssize * sizeof (wchar_t);
+    wchar_t *result = xmalloc (resultsize);
+    int ret;
+
+    ret = swprintf (result, resultsize, L"%.65537s", mbs);
+    TEST_COMPARE (ret, mbssize - 1);
+    TEST_COMPARE_BLOB (result, (ret + 1) * sizeof (wchar_t),
+		       expected, expectedsize * sizeof (wchar_t));
+
+    ret = swprintf (result, resultsize, L"%1$.65537s", mbs);
+    TEST_COMPARE (ret, mbssize - 1);
+    TEST_COMPARE_BLOB (result, (ret + 1) * sizeof (wchar_t),
+		       expected, expectedsize * sizeof (wchar_t));
+
+    /* Same test, but with an invalid multibyte sequence.  */
+    mbs[mbssize - 2] = 0xff;
+
+    ret = swprintf (result, resultsize, L"%.65537s", mbs);
+    TEST_COMPARE (ret, -1);
+
+    ret = swprintf (result, resultsize, L"%1$.65537s", mbs);
+    TEST_COMPARE (ret, -1);
+
+    free (mbs);
+    free (result);
+    free (expected);
+  }
+
+  return 0;
+}
+
+#include <support/test-driver.c>