x86-64 memset/wmemset: Properly handle the length parameter [BZ# 24097]

On x32, the size_t parameter may be passed in the lower 32 bits of a
64-bit register with the non-zero upper 32 bits.  The string/memory
functions written in assembly can only use the lower 32 bits of a
64-bit register as length or must clear the upper 32 bits before using
the full 64-bit register for length.

This pach fixes memset/wmemset for x32.  Tested on x86-64 and x32.  On
x86-64, libc.so is the same with and withou the fix.

	[BZ# 24097]
	CVE-2019-6488
	* sysdeps/x86_64/multiarch/memset-avx512-no-vzeroupper.S: Use
	RDX_LP for length.  Clear the upper 32 bits of RDX register.
	* sysdeps/x86_64/multiarch/memset-vec-unaligned-erms.S: Likewise.
	* sysdeps/x86_64/x32/Makefile (tests): Add tst-size_t-wmemset.
	* sysdeps/x86_64/x32/tst-size_t-memset.c: New file.
	* sysdeps/x86_64/x32/tst-size_t-wmemset.c: Likewise.

3 files changed, 95 insertions, 2 deletions

diff --git a/sysdeps/x86_64/x32/Makefile b/sysdeps/x86_64/x32/Makefile
index e99dbd7..98bd9ae 100644
--- a/sysdeps/x86_64/x32/Makefile
+++ b/sysdeps/x86_64/x32/Makefile
@@ -7,9 +7,9 @@ endif
 
 ifeq ($(subdir),string)
 tests += tst-size_t-memchr tst-size_t-memcmp tst-size_t-memcpy \
-	 tst-size_t-memrchr
+	 tst-size_t-memrchr tst-size_t-memset
 endif
 
 ifeq ($(subdir),wcsmbs)
-tests += tst-size_t-wmemchr tst-size_t-wmemcmp
+tests += tst-size_t-wmemchr tst-size_t-wmemcmp tst-size_t-wmemset
 endif
diff --git a/sysdeps/x86_64/x32/tst-size_t-memset.c b/sysdeps/x86_64/x32/tst-size_t-memset.c
new file mode 100644
index 0000000..2c367af
--- /dev/null
+++ b/sysdeps/x86_64/x32/tst-size_t-memset.c
@@ -0,0 +1,73 @@
+/* Test memset with size_t in the lower 32 bits of 64-bit register.
+   Copyright (C) 2019 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
+   <http://www.gnu.org/licenses/>.  */
+
+#ifdef WIDE
+# define TEST_NAME "wmemset"
+#else
+# define TEST_NAME "memset"
+#endif /* WIDE */
+
+#include "test-size_t.h"
+
+#ifdef WIDE
+# include <wchar.h>
+# define MEMSET wmemset
+# define CHAR wchar_t
+#else
+# define MEMSET memset
+# define CHAR char
+#endif /* WIDE */
+
+IMPL (MEMSET, 1)
+
+typedef CHAR *(*proto_t) (CHAR *, int, size_t);
+
+static void *
+__attribute__ ((noinline, noclone))
+do_memset (parameter_t a, parameter_t b)
+{
+  return CALL (&b, a.p, (uintptr_t) b.p, a.len);
+}
+
+static int
+test_main (void)
+{
+  test_init ();
+
+  CHAR ch = 0x23;
+  parameter_t src = { { page_size / sizeof (CHAR) }, buf2 };
+  parameter_t c = { { 0 }, (void *) (uintptr_t) ch };
+
+  int ret = 0;
+  FOR_EACH_IMPL (impl, 0)
+    {
+      c.fn = impl->fn;
+      CHAR *p = (CHAR *) do_memset (src, c);
+      size_t i;
+      for (i = 0; i < src.len; i++)
+	if (p[i] != ch)
+	  {
+	    error (0, 0, "Wrong result in function %s", impl->name);
+	    ret = 1;
+	  }
+    }
+
+  return ret ? EXIT_FAILURE : EXIT_SUCCESS;
+}
+
+#include <support/test-driver.c>
diff --git a/sysdeps/x86_64/x32/tst-size_t-wmemset.c b/sysdeps/x86_64/x32/tst-size_t-wmemset.c
new file mode 100644
index 0000000..955eb48
--- /dev/null
+++ b/sysdeps/x86_64/x32/tst-size_t-wmemset.c
@@ -0,0 +1,20 @@
+/* Test wmemset with size_t in the lower 32 bits of 64-bit register.
+   Copyright (C) 2019 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
+   <http://www.gnu.org/licenses/>.  */
+
+#define WIDE 1
+#include "tst-size_t-memset.c"