From bd6061191c63fb24025f3bb4cfc88519024f2b7a Mon Sep 17 00:00:00 2001

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

Date: Wed, 2 Mar 2022 14:03:51 -0800

Subject: [PATCH] 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.

(cherry picked from commit 82d0b4a4d76db554eb6757acb790fcea30b19965)

---

 .../multiarch/memset-avx512-no-vzeroupper.S   |  6 +-

 .../multiarch/memset-vec-unaligned-erms.S     | 34 +++++----

 sysdeps/x86_64/x32/Makefile                   |  4 +-

 sysdeps/x86_64/x32/tst-size_t-memset.c        | 73 +++++++++++++++++++

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

 5 files changed, 121 insertions(+), 16 deletions(-)

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

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

diff --git a/sysdeps/x86_64/multiarch/memset-avx512-no-vzeroupper.S b/sysdeps/x86_64/multiarch/memset-avx512-no-vzeroupper.S

index 689cc119..99e25519 100644

--- a/sysdeps/x86_64/multiarch/memset-avx512-no-vzeroupper.S

+++ b/sysdeps/x86_64/multiarch/memset-avx512-no-vzeroupper.S

@@ -29,12 +29,16 @@

 	.section .text.avx512,"ax",@progbits

 #if defined PIC

 ENTRY (MEMSET_CHK)

-	cmpq	%rdx, %rcx

+	cmp	%RDX_LP, %RCX_LP

 	jb	HIDDEN_JUMPTARGET (__chk_fail)

 END (MEMSET_CHK)

 #endif

 ENTRY (MEMSET)

+# ifdef __ILP32__

+	/* Clear the upper 32 bits.  */

+	mov	%edx, %edx

+# endif

 	vpxor	%xmm0, %xmm0, %xmm0

 	vmovd	%esi, %xmm1

 	lea	(%rdi, %rdx), %rsi

diff --git a/sysdeps/x86_64/multiarch/memset-vec-unaligned-erms.S b/sysdeps/x86_64/multiarch/memset-vec-unaligned-erms.S

index 270a1d49..9a0fd818 100644

--- a/sysdeps/x86_64/multiarch/memset-vec-unaligned-erms.S

+++ b/sysdeps/x86_64/multiarch/memset-vec-unaligned-erms.S

@@ -65,8 +65,8 @@

 	.section SECTION(.text),"ax",@progbits

 #if VEC_SIZE == 16 && IS_IN (libc)

 ENTRY (__bzero)

-	movq	%rdi, %rax /* Set return value.  */

-	movq	%rsi, %rdx /* Set n.  */

+	mov	%RDI_LP, %RAX_LP /* Set return value.  */

+	mov	%RSI_LP, %RDX_LP /* Set n.  */

 	pxor	%xmm0, %xmm0

 	jmp	L(entry_from_bzero)

 END (__bzero)

@@ -76,13 +76,13 @@ weak_alias (__bzero, bzero)

 #if IS_IN (libc)

 # if defined SHARED

 ENTRY_CHK (WMEMSET_CHK_SYMBOL (__wmemset_chk, unaligned))

-	cmpq	%rdx, %rcx

+	cmp	%RDX_LP, %RCX_LP

 	jb	HIDDEN_JUMPTARGET (__chk_fail)

 END_CHK (WMEMSET_CHK_SYMBOL (__wmemset_chk, unaligned))

 # endif

 ENTRY (WMEMSET_SYMBOL (__wmemset, unaligned))

-	shlq	$2, %rdx

+	shl	$2, %RDX_LP

 	WMEMSET_VDUP_TO_VEC0_AND_SET_RETURN (%esi, %rdi)

 	jmp	L(entry_from_bzero)

 END (WMEMSET_SYMBOL (__wmemset, unaligned))

@@ -90,13 +90,17 @@ END (WMEMSET_SYMBOL (__wmemset, unaligned))

 #if defined SHARED && IS_IN (libc)

 ENTRY_CHK (MEMSET_CHK_SYMBOL (__memset_chk, unaligned))

-	cmpq	%rdx, %rcx

+	cmp	%RDX_LP, %RCX_LP

 	jb	HIDDEN_JUMPTARGET (__chk_fail)

 END_CHK (MEMSET_CHK_SYMBOL (__memset_chk, unaligned))

 #endif

 ENTRY (MEMSET_SYMBOL (__memset, unaligned))

 	MEMSET_VDUP_TO_VEC0_AND_SET_RETURN (%esi, %rdi)

+# ifdef __ILP32__

+	/* Clear the upper 32 bits.  */

+	mov	%edx, %edx

+# endif

 L(entry_from_bzero):

 	cmpq	$VEC_SIZE, %rdx

 	jb	L(less_vec)

@@ -112,14 +116,14 @@ END (MEMSET_SYMBOL (__memset, unaligned))

 # if VEC_SIZE == 16

 ENTRY (__memset_chk_erms)

-	cmpq	%rdx, %rcx

+	cmp	%RDX_LP, %RCX_LP

 	jb	HIDDEN_JUMPTARGET (__chk_fail)

 END (__memset_chk_erms)

 /* Only used to measure performance of REP STOSB.  */

 ENTRY (__memset_erms)

 	/* Skip zero length.  */

-	testq	%rdx, %rdx

+	test	%RDX_LP, %RDX_LP

 	jnz	 L(stosb)

 	movq	%rdi, %rax

 	ret

@@ -131,11 +135,11 @@ ENTRY (MEMSET_SYMBOL (__memset, erms))

 L(stosb):

 	/* Issue vzeroupper before rep stosb.  */

 	VZEROUPPER

-	movq	%rdx, %rcx

+	mov	%RDX_LP, %RCX_LP

 	movzbl	%sil, %eax

-	movq	%rdi, %rdx

+	mov	%RDI_LP, %RDX_LP

 	rep stosb

-	movq	%rdx, %rax

+	mov	%RDX_LP, %RAX_LP

 	ret

 # if VEC_SIZE == 16

 END (__memset_erms)

@@ -145,16 +149,20 @@ END (MEMSET_SYMBOL (__memset, erms))

 # if defined SHARED && IS_IN (libc)

 ENTRY_CHK (MEMSET_CHK_SYMBOL (__memset_chk, unaligned_erms))

-	cmpq	%rdx, %rcx

+	cmp	%RDX_LP, %RCX_LP

 	jb	HIDDEN_JUMPTARGET (__chk_fail)

 END_CHK (MEMSET_CHK_SYMBOL (__memset_chk, unaligned_erms))

 # endif

 ENTRY (MEMSET_SYMBOL (__memset, unaligned_erms))

 	MEMSET_VDUP_TO_VEC0_AND_SET_RETURN (%esi, %rdi)

-	cmpq	$VEC_SIZE, %rdx

+# ifdef __ILP32__

+	/* Clear the upper 32 bits.  */

+	mov	%edx, %edx

+# endif

+	cmp	$VEC_SIZE, %RDX_LP

 	jb	L(less_vec)

-	cmpq	$(VEC_SIZE * 2), %rdx

+	cmp	$(VEC_SIZE * 2), %RDX_LP

 	ja	L(stosb_more_2x_vec)

 	/* From VEC and to 2 * VEC.  No branch when size == VEC_SIZE.  */

 	VMOVU	%VEC(0), -VEC_SIZE(%rdi,%rdx)

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

index e99dbd7c..98bd9ae9 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 00000000..2c367af6

--- /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 00000000..955eb488

--- /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"

-- 

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