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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.
This commit is contained in:
H.J. Lu 2019-01-21 11:33:52 -08:00
parent 82d0b4a4d7
commit ee915088a0
8 changed files with 183 additions and 11 deletions
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13
ChangeLog
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@ -1,3 +1,16 @@
2019-01-21 H.J. Lu <hongjiu.lu@intel.com>
[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.
2019-01-21 H.J. Lu <hongjiu.lu@intel.com>
[BZ# 24097]

6
sysdeps/x86_64/multiarch/strcmp-avx2.S
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@ -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

6
sysdeps/x86_64/multiarch/strcmp-sse42.S
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@ -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

6
sysdeps/x86_64/strcmp.S
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@ -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

6
sysdeps/x86_64/x32/Makefile
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@ -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

59
sysdeps/x86_64/x32/tst-size_t-strncasecmp.c Normal file
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@ -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>

78
sysdeps/x86_64/x32/tst-size_t-strncmp.c Normal file
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@ -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>

20
sysdeps/x86_64/x32/tst-size_t-wcsncmp.c Normal file
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@ -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"