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Merge "add fortified implementations of fread/fwrite"

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This commit is contained in:
Yabin Cui 2015-07-27 22:46:29 +00:00 committed by Gerrit Code Review
commit 8af3263349
8 changed files with 223 additions and 0 deletions
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2
libc/Android.mk
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@ -70,6 +70,8 @@ libc_common_src_files := \
libc_common_src_files += \
bionic/__FD_chk.cpp \
bionic/__fgets_chk.cpp \
bionic/__fread_chk.cpp \
bionic/__fwrite_chk.cpp \
bionic/__memchr_chk.cpp \
bionic/__memmove_chk.cpp \
bionic/__memrchr_chk.cpp \

47
libc/bionic/__fread_chk.cpp Normal file
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@ -0,0 +1,47 @@
/*
* Copyright (C) 2015 The Android Open Source Project
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* * Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* * Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in
* the documentation and/or other materials provided with the
* distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
* OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
* OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/
#undef _FORTIFY_SOURCE
#include <stdio.h>
#include <sys/cdefs.h>
#include "private/libc_logging.h"
extern "C" size_t __fread_chk(void * __restrict buf, size_t size, size_t count,
FILE * __restrict stream, size_t buf_size) {
size_t total;
if (__predict_false(__size_mul_overflow(size, count, &total))) {
// overflow: trigger the error path in fread
return fread(buf, size, count, stream);
}
if (__predict_false(total > buf_size)) {
__fortify_chk_fail("fread: prevented write past end of buffer", 0);
}
return fread(buf, size, count, stream);
}

47
libc/bionic/__fwrite_chk.cpp Normal file
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@ -0,0 +1,47 @@
/*
* Copyright (C) 2015 The Android Open Source Project
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* * Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* * Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in
* the documentation and/or other materials provided with the
* distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
* OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
* OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/
#undef _FORTIFY_SOURCE
#include <stdio.h>
#include <sys/cdefs.h>
#include "private/libc_logging.h"
extern "C" size_t __fwrite_chk(const void * __restrict buf, size_t size, size_t count,
FILE * __restrict stream, size_t buf_size) {
size_t total;
if (__predict_false(__size_mul_overflow(size, count, &total))) {
// overflow: trigger the error path in fwrite
return fwrite(buf, size, count, stream);
}
if (__predict_false(total > buf_size)) {
__fortify_chk_fail("fwrite: prevented read past end of buffer", 0);
}
return fwrite(buf, size, count, stream);
}

62
libc/include/stdio.h
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@ -382,6 +382,16 @@ extern char* __fgets_real(char*, int, FILE*) __RENAME(fgets);
__errordecl(__fgets_too_big_error, "fgets called with size bigger than buffer");
__errordecl(__fgets_too_small_error, "fgets called with size less than zero");
extern size_t __fread_chk(void * __restrict, size_t, size_t, FILE * __restrict, size_t);
extern size_t __fread_real(void * __restrict, size_t, size_t, FILE * __restrict) __RENAME(fread);
__errordecl(__fread_too_big_error, "fread called with size * count bigger than buffer");
__errordecl(__fread_overflow, "fread called with overflowing size * count");
extern size_t __fwrite_chk(const void * __restrict, size_t, size_t, FILE * __restrict, size_t);
extern size_t __fwrite_real(const void * __restrict, size_t, size_t, FILE * __restrict) __RENAME(fwrite);
__errordecl(__fwrite_too_big_error, "fwrite called with size * count bigger than buffer");
__errordecl(__fwrite_overflow, "fwrite called with overflowing size * count");
#if defined(__BIONIC_FORTIFY)
__BIONIC_FORTIFY_INLINE
@ -428,6 +438,58 @@ int sprintf(char *dest, const char *format, ...)
}
#endif
__BIONIC_FORTIFY_INLINE
size_t fread(void * __restrict buf, size_t size, size_t count, FILE * __restrict stream) {
size_t bos = __bos0(buf);
#if !defined(__clang__)
if (bos == __BIONIC_FORTIFY_UNKNOWN_SIZE) {
return __fread_real(buf, size, count, stream);
}
if (__builtin_constant_p(size) && __builtin_constant_p(count)) {
size_t total;
if (__size_mul_overflow(size, count, &total)) {
__fread_overflow();
}
if (total > bos) {
__fread_too_big_error();
}
return __fread_real(buf, size, count, stream);
}
#endif
return __fread_chk(buf, size, count, stream, bos);
}
__BIONIC_FORTIFY_INLINE
size_t fwrite(const void * __restrict buf, size_t size, size_t count, FILE * __restrict stream) {
size_t bos = __bos0(buf);
#if !defined(__clang__)
if (bos == __BIONIC_FORTIFY_UNKNOWN_SIZE) {
return __fwrite_real(buf, size, count, stream);
}
if (__builtin_constant_p(size) && __builtin_constant_p(count)) {
size_t total;
if (__size_mul_overflow(size, count, &total)) {
__fwrite_overflow();
}
if (total > bos) {
__fwrite_too_big_error();
}
return __fwrite_real(buf, size, count, stream);
}
#endif
return __fwrite_chk(buf, size, count, stream, bos);
}
#if !defined(__clang__)
__BIONIC_FORTIFY_INLINE

15
libc/include/sys/cdefs.h
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@ -578,4 +578,19 @@
#define _BIONIC_NOT_BEFORE_21(x)
#endif /* __ANDROID_API__ >= 21 */
#if __has_builtin(__builtin_umul_overflow) || __GNUC__ >= 5
#if __LP64__
#define __size_mul_overflow(a, b, result) __builtin_umull_overflow(a, b, result)
#else
#define __size_mul_overflow(a, b, result) __builtin_umul_overflow(a, b, result)
#endif
#else
static __inline__ __always_inline int __size_mul_overflow(__SIZE_TYPE__ a, __SIZE_TYPE__ b,
__SIZE_TYPE__ *result) {
*result = a * b;
static const __SIZE_TYPE__ mul_no_overflow = 1UL << (sizeof(__SIZE_TYPE__) * 4);
return (a >= mul_no_overflow || b >= mul_no_overflow) && a > 0 && (__SIZE_TYPE__)-1 / a < b;
}
#endif
#endif /* !_SYS_CDEFS_H_ */

2
libc/libc.map
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@ -1334,6 +1334,8 @@ LIBC {
LIBC_N {
global:
__fread_chk;
__fwrite_chk;
getgrgid_r;
getgrnam_r;
} LIBC;

32
tests/fortify_compilation_test.cpp
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@ -230,3 +230,35 @@ void test_ppoll() {
// clang should emit a warning, but doesn't
ppoll(fds, 2, &timeout, NULL);
}
void test_fread_overflow() {
char buf[4];
// NOLINTNEXTLINE(whitespace/line_length)
// GCC: error: call to '__fread_overflow' declared with attribute error: fread called with overflowing size * count
// clang should emit a warning, but doesn't
fread(buf, 2, (size_t)-1, stdin);
}
void test_fread_too_big() {
char buf[4];
// NOLINTNEXTLINE(whitespace/line_length)
// GCC: error: call to '__fread_too_big_error' declared with attribute error: fread called with size * count bigger than buffer
// clang should emit a warning, but doesn't
fread(buf, 1, 5, stdin);
}
void test_fwrite_overflow() {
char buf[4];
// NOLINTNEXTLINE(whitespace/line_length)
// GCC: error: call to '__fwrite_overflow' declared with attribute error: fwrite called with overflowing size * count
// clang should emit a warning, but doesn't
fwrite(buf, 2, (size_t)-1, stdout);
}
void test_fwrite_too_big() {
char buf[4] = {0};
// NOLINTNEXTLINE(whitespace/line_length)
// GCC: error: call to '__fwrite_too_big_error' declared with attribute error: fwrite called with size * count bigger than buffer
// clang should emit a warning, but doesn't
fwrite(buf, 1, 5, stdout);
}

16
tests/fortify_test.cpp
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@ -647,6 +647,22 @@ TEST_F(DEATHTEST, read_fortified) {
close(fd);
}
TEST_F(DEATHTEST, fread_fortified) {
char buf[1];
size_t ct = atoi("2"); // prevent optimizations
FILE* fp = fopen("/dev/null", "r");
ASSERT_FORTIFY(fread(buf, 1, ct, fp));
fclose(fp);
}
TEST_F(DEATHTEST, fwrite_fortified) {
char buf[1] = {0};
size_t ct = atoi("2"); // prevent optimizations
FILE* fp = fopen("/dev/null", "w");
ASSERT_FORTIFY(fwrite(buf, 1, ct, fp));
fclose(fp);
}
TEST_F(DEATHTEST, readlink_fortified) {
char buf[1];
size_t ct = atoi("2"); // prevent optimizations