From ea31ff23cc0f5577d6947a717a2d733d7963f5c6 Mon Sep 17 00:00:00 2001

From: "H.J. Lu" <hjl.tools@gmail.com>

Date: Fri, 1 Feb 2019 12:17:09 -0800

Subject: [PATCH] x86-64 memchr/wmemchr: 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 memchr/wmemchr 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/memchr.S: Use RDX_LP for length.  Clear the

	upper 32 bits of RDX register.

	* sysdeps/x86_64/multiarch/memchr-avx2.S: Likewise.

	* sysdeps/x86_64/x32/Makefile (tests): Add tst-size_t-memchr and

	tst-size_t-wmemchr.

	* sysdeps/x86_64/x32/test-size_t.h: New file.

	* sysdeps/x86_64/x32/tst-size_t-memchr.c: Likewise.

	* sysdeps/x86_64/x32/tst-size_t-wmemchr.c: Likewise.

(cherry picked from commit 97700a34f36721b11a754cf37a1cc40695ece1fd)

---

 sysdeps/x86_64/memchr.S                 | 10 ++--

 sysdeps/x86_64/multiarch/memchr-avx2.S  |  8 ++-

 sysdeps/x86_64/x32/Makefile             |  8 +++

 sysdeps/x86_64/x32/test-size_t.h        | 35 ++++++++++++

 sysdeps/x86_64/x32/tst-size_t-memchr.c  | 72 +++++++++++++++++++++++++

 sysdeps/x86_64/x32/tst-size_t-wmemchr.c | 20 +++++++

 6 files changed, 148 insertions(+), 5 deletions(-)

 create mode 100644 sysdeps/x86_64/x32/test-size_t.h

 create mode 100644 sysdeps/x86_64/x32/tst-size_t-memchr.c

 create mode 100644 sysdeps/x86_64/x32/tst-size_t-wmemchr.c

diff --git a/sysdeps/x86_64/memchr.S b/sysdeps/x86_64/memchr.S

index feef5d4f..cb320257 100644

--- a/sysdeps/x86_64/memchr.S

+++ b/sysdeps/x86_64/memchr.S

@@ -34,12 +34,16 @@ ENTRY(MEMCHR)

 	mov	%edi, %ecx

 #ifdef USE_AS_WMEMCHR

-	test	%rdx, %rdx

+	test	%RDX_LP, %RDX_LP

 	jz	L(return_null)

-	shl	$2, %rdx

+	shl	$2, %RDX_LP

 #else

+# ifdef __ILP32__

+	/* Clear the upper 32 bits.  */

+	movl	%edx, %edx

+# endif

 	punpcklbw %xmm1, %xmm1

-	test	%rdx, %rdx

+	test	%RDX_LP, %RDX_LP

 	jz	L(return_null)

 	punpcklbw %xmm1, %xmm1

 #endif

diff --git a/sysdeps/x86_64/multiarch/memchr-avx2.S b/sysdeps/x86_64/multiarch/memchr-avx2.S

index 5f5e7725..c81da19b 100644

--- a/sysdeps/x86_64/multiarch/memchr-avx2.S

+++ b/sysdeps/x86_64/multiarch/memchr-avx2.S

@@ -40,16 +40,20 @@

 ENTRY (MEMCHR)

 # ifndef USE_AS_RAWMEMCHR

 	/* Check for zero length.  */

-	testq	%rdx, %rdx

+	test	%RDX_LP, %RDX_LP

 	jz	L(null)

 # endif

 	movl	%edi, %ecx

 	/* Broadcast CHAR to YMM0.  */

 	vmovd	%esi, %xmm0

 # ifdef USE_AS_WMEMCHR

-	shl	$2, %rdx

+	shl	$2, %RDX_LP

 	vpbroadcastd %xmm0, %ymm0

 # else

+#  ifdef __ILP32__

+	/* Clear the upper 32 bits.  */

+	movl	%edx, %edx

+#  endif

 	vpbroadcastb %xmm0, %ymm0

 # endif

 	/* Check if we may cross page boundary with one vector load.  */

diff --git a/sysdeps/x86_64/x32/Makefile b/sysdeps/x86_64/x32/Makefile

index f2ebc24f..7d528889 100644

--- a/sysdeps/x86_64/x32/Makefile

+++ b/sysdeps/x86_64/x32/Makefile

@@ -4,3 +4,11 @@ ifeq ($(subdir),math)

 # 64-bit llround.  Add -fno-builtin-lround to silence the compiler.

 CFLAGS-s_llround.c += -fno-builtin-lround

 endif

+

+ifeq ($(subdir),string)

+tests += tst-size_t-memchr

+endif

+

+ifeq ($(subdir),wcsmbs)

+tests += tst-size_t-wmemchr

+endif

diff --git a/sysdeps/x86_64/x32/test-size_t.h b/sysdeps/x86_64/x32/test-size_t.h

new file mode 100644

index 00000000..78a94086

--- /dev/null

+++ b/sysdeps/x86_64/x32/test-size_t.h

@@ -0,0 +1,35 @@

+/* Test string/memory functions 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 TEST_MAIN

+#include <string/test-string.h>

+

+/* On x32, parameter_t may be passed in a 64-bit register with the LEN

+   field in the lower 32 bits.  When the LEN field of 64-bit register

+   is passed to string/memory function as the size_t parameter, only

+   the lower 32 bits can be used.  */

+typedef struct

+{

+  union

+    {

+      size_t len;

+      void (*fn) (void);

+    };

+  void *p;

+} parameter_t;

diff --git a/sysdeps/x86_64/x32/tst-size_t-memchr.c b/sysdeps/x86_64/x32/tst-size_t-memchr.c

new file mode 100644

index 00000000..29a3daf1

--- /dev/null

+++ b/sysdeps/x86_64/x32/tst-size_t-memchr.c

@@ -0,0 +1,72 @@

+/* Test memchr 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/>.  */

+

+#ifndef WIDE

+# define TEST_NAME "memchr"

+#else

+# define TEST_NAME "wmemchr"

+#endif /* WIDE */

+#include "test-size_t.h"

+

+#ifndef WIDE

+# define MEMCHR memchr

+# define CHAR char

+# define UCHAR unsigned char

+#else

+# include <wchar.h>

+# define MEMCHR wmemchr

+# define CHAR wchar_t

+# define UCHAR wchar_t

+#endif /* WIDE */

+

+IMPL (MEMCHR, 1)

+

+typedef CHAR * (*proto_t) (const CHAR*, int, size_t);

+

+static CHAR *

+__attribute__ ((noinline, noclone))

+do_memchr (parameter_t a, parameter_t b)

+{

+  return CALL (&b, a.p, (uintptr_t) b.p, a.len);

+}

+

+static int

+test_main (void)

+{

+  test_init ();

+

+  parameter_t src = { { page_size / sizeof (CHAR) }, buf2 };

+  parameter_t c = { { 0 }, (void *) (uintptr_t) 0x12 };

+

+  int ret = 0;

+  FOR_EACH_IMPL (impl, 0)

+    {

+      c.fn = impl->fn;

+      CHAR *res = do_memchr (src, c);

+      if (res)

+	{

+	  error (0, 0, "Wrong result in function %s: %p != NULL",

+		 impl->name, res);

+	  ret = 1;

+	}

+    }

+

+  return ret ? EXIT_FAILURE : EXIT_SUCCESS;

+}

+

+#include <support/test-driver.c>

diff --git a/sysdeps/x86_64/x32/tst-size_t-wmemchr.c b/sysdeps/x86_64/x32/tst-size_t-wmemchr.c

new file mode 100644

index 00000000..877801d6

--- /dev/null

+++ b/sysdeps/x86_64/x32/tst-size_t-wmemchr.c

@@ -0,0 +1,20 @@

+/* Test wmemchr 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-memchr.c"

-- 

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