From 323c698927f67a153e278cc99870998a9c7c87af Mon Sep 17 00:00:00 2001

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

Date: Fri, 1 Feb 2019 12:22:33 -0800

Subject: [PATCH] x86-64 strncmp family: 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 the strncmp family 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/strcmp-avx2.S: Use RDX_LP for length.

	* sysdeps/x86_64/multiarch/strcmp-sse42.S: Likewise.

	* sysdeps/x86_64/strcmp.S: Likewise.

	* sysdeps/x86_64/x32/Makefile (tests): Add tst-size_t-strncasecmp,

	tst-size_t-strncmp and tst-size_t-wcsncmp.

	* sysdeps/x86_64/x32/tst-size_t-strncasecmp.c: New file.

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

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

(cherry picked from commit ee915088a0231cd421054dbd8abab7aadf331153)

---

 sysdeps/x86_64/multiarch/strcmp-avx2.S      |  6 +-

 sysdeps/x86_64/multiarch/strcmp-sse42.S     |  6 +-

 sysdeps/x86_64/strcmp.S                     |  6 +-

 sysdeps/x86_64/x32/Makefile                 |  6 +-

 sysdeps/x86_64/x32/tst-size_t-strncasecmp.c | 59 ++++++++++++++++

 sysdeps/x86_64/x32/tst-size_t-strncmp.c     | 78 +++++++++++++++++++++

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

 7 files changed, 170 insertions(+), 11 deletions(-)

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

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

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

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

index 327e3d87..156c1949 100644

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

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

@@ -79,15 +79,15 @@

 ENTRY (STRCMP)

 # ifdef USE_AS_STRNCMP

 	/* Check for simple cases (0 or 1) in offset.  */

-	cmp	$1, %rdx

+	cmp	$1, %RDX_LP

 	je	L(char0)

 	jb	L(zero)

 #  ifdef USE_AS_WCSCMP

 	/* Convert units: from wide to byte char.  */

-	shl	$2, %rdx

+	shl	$2, %RDX_LP

 #  endif

 	/* Register %r11 tracks the maximum offset.  */

-	movq	%rdx, %r11

+	mov	%RDX_LP, %R11_LP

 # endif

 	movl	%edi, %eax

 	xorl	%edx, %edx

diff --git a/sysdeps/x86_64/multiarch/strcmp-sse42.S b/sysdeps/x86_64/multiarch/strcmp-sse42.S

index d3c07bd2..a1ebea46 100644

--- a/sysdeps/x86_64/multiarch/strcmp-sse42.S

+++ b/sysdeps/x86_64/multiarch/strcmp-sse42.S

@@ -156,11 +156,11 @@ STRCMP_SSE42:

 #endif

 #if defined USE_AS_STRNCMP || defined USE_AS_STRNCASECMP_L

-	test	%rdx, %rdx

+	test	%RDX_LP, %RDX_LP

 	je	LABEL(strcmp_exitz)

-	cmp	$1, %rdx

+	cmp	$1, %RDX_LP

 	je	LABEL(Byte0)

-	mov	%rdx, %r11

+	mov	%RDX_LP, %R11_LP

 #endif

 	mov	%esi, %ecx

 	mov	%edi, %eax

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

index e16945b9..f47c8ad4 100644

--- a/sysdeps/x86_64/strcmp.S

+++ b/sysdeps/x86_64/strcmp.S

@@ -135,11 +135,11 @@ ENTRY (STRCMP)

  * This implementation uses SSE to compare up to 16 bytes at a time.

  */

 #if defined USE_AS_STRNCMP || defined USE_AS_STRNCASECMP_L

-	test	%rdx, %rdx

+	test	%RDX_LP, %RDX_LP

 	je	LABEL(strcmp_exitz)

-	cmp	$1, %rdx

+	cmp	$1, %RDX_LP

 	je	LABEL(Byte0)

-	mov	%rdx, %r11

+	mov	%RDX_LP, %R11_LP

 #endif

 	mov	%esi, %ecx

 	mov	%edi, %eax

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

index 98bd9ae9..db302839 100644

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

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

@@ -7,9 +7,11 @@ endif

 ifeq ($(subdir),string)

 tests += tst-size_t-memchr tst-size_t-memcmp tst-size_t-memcpy \

-	 tst-size_t-memrchr tst-size_t-memset

+	 tst-size_t-memrchr tst-size_t-memset tst-size_t-strncasecmp \

+	 tst-size_t-strncmp

 endif

 ifeq ($(subdir),wcsmbs)

-tests += tst-size_t-wmemchr tst-size_t-wmemcmp tst-size_t-wmemset

+tests += tst-size_t-wmemchr tst-size_t-wmemcmp tst-size_t-wmemset \

+	 tst-size_t-wcsncmp

 endif

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

new file mode 100644

index 00000000..86233593

--- /dev/null

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

@@ -0,0 +1,59 @@

+/* Test strncaecmp 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_NAME "strncasecmp"

+#include "test-size_t.h"

+

+IMPL (strncasecmp, 1)

+

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

+

+static int

+__attribute__ ((noinline, noclone))

+do_strncasecmp (parameter_t a, parameter_t b)

+{

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

+}

+

+static int

+test_main (void)

+{

+  test_init ();

+

+  parameter_t dest = { { page_size }, buf1 };

+  parameter_t src = { { 0 }, buf2 };

+

+  strncpy ((char *) buf1, (const char *) buf2, page_size);

+

+  int ret = 0;

+  FOR_EACH_IMPL (impl, 0)

+    {

+      src.fn = impl->fn;

+      int res = do_strncasecmp (dest, src);

+      if (res)

+	{

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

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

new file mode 100644

index 00000000..54e6bd83

--- /dev/null

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

@@ -0,0 +1,78 @@

+/* Test strncmp 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 "wcsncmp"

+#else

+# define TEST_NAME "strncmp"

+#endif

+

+#include "test-size_t.h"

+

+#ifdef WIDE

+# include <wchar.h>

+

+# define STRNCMP wcsncmp

+# define STRNCPY wcsncpy

+# define CHAR wchar_t

+#else

+# define STRNCMP strncmp

+# define STRNCPY strncpy

+# define CHAR char

+#endif

+

+IMPL (STRNCMP, 1)

+

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

+

+

+static int

+__attribute__ ((noinline, noclone))

+do_strncmp (parameter_t a, parameter_t b)

+{

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

+}

+

+static int

+test_main (void)

+{

+  test_init ();

+

+  size_t size = page_size / sizeof (CHAR);

+  parameter_t dest = { { size }, buf1 };

+  parameter_t src = { { 0 }, buf2 };

+

+  STRNCPY ((CHAR *) buf1, (const CHAR *) buf2, size);

+

+  int ret = 0;

+  FOR_EACH_IMPL (impl, 0)

+    {

+      src.fn = impl->fn;

+      int res = do_strncmp (dest, src);

+      if (res)

+	{

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

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

new file mode 100644

index 00000000..4829647c

--- /dev/null

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

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

+/* Test wcsncmp 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-strncmp.c"

-- 

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