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x86-64 memrchr: 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 memrchr 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/memrchr.S: Use RDX_LP for length.
	* sysdeps/x86_64/multiarch/memrchr-avx2.S: Likewise.
	* sysdeps/x86_64/x32/Makefile (tests): Add tst-size_t-memrchr.
	* sysdeps/x86_64/x32/tst-size_t-memrchr.c: New file.
This commit is contained in:
H.J. Lu 2019-01-21 11:29:58 -08:00
parent 231c56760c
commit ecd8b842cf
5 changed files with 72 additions and 5 deletions
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9
ChangeLog
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@ -1,3 +1,12 @@
2019-01-21 H.J. Lu <hongjiu.lu@intel.com>
[BZ# 24097]
CVE-2019-6488
* sysdeps/x86_64/memrchr.S: Use RDX_LP for length.
* sysdeps/x86_64/multiarch/memrchr-avx2.S: Likewise.
* sysdeps/x86_64/x32/Makefile (tests): Add tst-size_t-memrchr.
* sysdeps/x86_64/x32/tst-size_t-memrchr.c: New file.
2019-01-21 H.J. Lu <hongjiu.lu@intel.com>
[BZ# 24097]

4
sysdeps/x86_64/memrchr.S
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@ -24,13 +24,13 @@
ENTRY (__memrchr)
movd %esi, %xmm1
sub $16, %rdx
sub $16, %RDX_LP
jbe L(length_less16)
punpcklbw %xmm1, %xmm1
punpcklbw %xmm1, %xmm1
add %rdx, %rdi
add %RDX_LP, %RDI_LP
pshufd $0, %xmm1, %xmm1
movdqu (%rdi), %xmm0

4
sysdeps/x86_64/multiarch/memrchr-avx2.S
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@ -32,10 +32,10 @@ ENTRY (__memrchr_avx2)
vmovd %esi, %xmm0
vpbroadcastb %xmm0, %ymm0
subq $VEC_SIZE, %rdx
sub $VEC_SIZE, %RDX_LP
jbe L(last_vec_or_less)
addq %rdx, %rdi
add %RDX_LP, %RDI_LP
/* Check the last VEC_SIZE bytes. */
vpcmpeqb (%rdi), %ymm0, %ymm1

3
sysdeps/x86_64/x32/Makefile
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@ -6,7 +6,8 @@ CFLAGS-s_llround.c += -fno-builtin-lround
endif
ifeq ($(subdir),string)
tests += tst-size_t-memchr tst-size_t-memcmp tst-size_t-memcpy
tests += tst-size_t-memchr tst-size_t-memcmp tst-size_t-memcpy \
tst-size_t-memrchr
endif
ifeq ($(subdir),wcsmbs)

57
sysdeps/x86_64/x32/tst-size_t-memrchr.c Normal file
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@ -0,0 +1,57 @@
/* Test memrchr 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 "memrchr"
#include "test-size_t.h"
IMPL (memchr, 1)
typedef void * (*proto_t) (const void *, int, size_t);
static void *
__attribute__ ((noinline, noclone))
do_memrchr (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 }, buf2 };
parameter_t c = { { 0 }, (void *) (uintptr_t) 0x12 };
int ret = 0;
FOR_EACH_IMPL (impl, 0)
{
c.fn = impl->fn;
void * res = do_memrchr (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>