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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