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FORTIFY_SOURCE: strcat / strncat optimize

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__strcat_chk and __strncat_chk are slightly inefficient,
because they end up traversing over the same memory region
two times.

This change optimizes __strcat_chk / __strncat_chk so they
only access the memory once. Although I haven't benchmarked these
changes, it should improve the performance of these functions.

__strlen_chk - expose this function, even if -D_FORTIFY_SOURCE
isn't defined. This is needed to compile libc itself without
-D_FORTIFY_SOURCE.

Change-Id: Id2c70dff55a276b47c59db27a03734d659f84b74
This commit is contained in:
Nick Kralevich
2013-05-30 16:48:53 -07:00
parent 72f59c84fd
commit cf870199d5
7 changed files with 354 additions and 40 deletions
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163
tests/fortify1_test.cpp
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@@ -76,3 +76,166 @@ TEST(Fortify1_DeathTest, strncat2_fortified) {
size_t n = atoi("10"); // avoid compiler optimizations
ASSERT_EXIT(strncat(buf, "0123456789", n), testing::KilledBySignal(SIGSEGV), "");
}
TEST(Fortify1_DeathTest, strcat_fortified) {
::testing::FLAGS_gtest_death_test_style = "threadsafe";
char src[11];
strcpy(src, "0123456789");
char buf[10];
buf[0] = '\0';
ASSERT_EXIT(strcat(buf, src), testing::KilledBySignal(SIGSEGV), "");
}
extern "C" char* __strncat_chk(char*, const char*, size_t, size_t);
extern "C" char* __strcat_chk(char*, const char*, size_t);
TEST(Fortify1, strncat) {
char buf[10];
memset(buf, 'A', sizeof(buf));
buf[0] = 'a';
buf[1] = '\0';
char* res = __strncat_chk(buf, "01234", sizeof(buf) - strlen(buf) - 1, sizeof(buf));
ASSERT_EQ(buf, res);
ASSERT_EQ('a', buf[0]);
ASSERT_EQ('0', buf[1]);
ASSERT_EQ('1', buf[2]);
ASSERT_EQ('2', buf[3]);
ASSERT_EQ('3', buf[4]);
ASSERT_EQ('4', buf[5]);
ASSERT_EQ('\0', buf[6]);
ASSERT_EQ('A', buf[7]);
ASSERT_EQ('A', buf[8]);
ASSERT_EQ('A', buf[9]);
}
TEST(Fortify1, strncat2) {
char buf[10];
memset(buf, 'A', sizeof(buf));
buf[0] = 'a';
buf[1] = '\0';
char* res = __strncat_chk(buf, "0123456789", 5, sizeof(buf));
ASSERT_EQ(buf, res);
ASSERT_EQ('a', buf[0]);
ASSERT_EQ('0', buf[1]);
ASSERT_EQ('1', buf[2]);
ASSERT_EQ('2', buf[3]);
ASSERT_EQ('3', buf[4]);
ASSERT_EQ('4', buf[5]);
ASSERT_EQ('\0', buf[6]);
ASSERT_EQ('A', buf[7]);
ASSERT_EQ('A', buf[8]);
ASSERT_EQ('A', buf[9]);
}
TEST(Fortify1, strncat3) {
char buf[10];
memset(buf, 'A', sizeof(buf));
buf[0] = '\0';
char* res = __strncat_chk(buf, "0123456789", 5, sizeof(buf));
ASSERT_EQ(buf, res);
ASSERT_EQ('0', buf[0]);
ASSERT_EQ('1', buf[1]);
ASSERT_EQ('2', buf[2]);
ASSERT_EQ('3', buf[3]);
ASSERT_EQ('4', buf[4]);
ASSERT_EQ('\0', buf[5]);
ASSERT_EQ('A', buf[6]);
ASSERT_EQ('A', buf[7]);
ASSERT_EQ('A', buf[8]);
ASSERT_EQ('A', buf[9]);
}
TEST(Fortify1, strncat4) {
char buf[10];
memset(buf, 'A', sizeof(buf));
buf[9] = '\0';
char* res = __strncat_chk(buf, "", 5, sizeof(buf));
ASSERT_EQ(buf, res);
ASSERT_EQ('A', buf[0]);
ASSERT_EQ('A', buf[1]);
ASSERT_EQ('A', buf[2]);
ASSERT_EQ('A', buf[3]);
ASSERT_EQ('A', buf[4]);
ASSERT_EQ('A', buf[5]);
ASSERT_EQ('A', buf[6]);
ASSERT_EQ('A', buf[7]);
ASSERT_EQ('A', buf[8]);
ASSERT_EQ('\0', buf[9]);
}
TEST(Fortify1, strncat5) {
char buf[10];
memset(buf, 'A', sizeof(buf));
buf[0] = 'a';
buf[1] = '\0';
char* res = __strncat_chk(buf, "01234567", 8, sizeof(buf));
ASSERT_EQ(buf, res);
ASSERT_EQ('a', buf[0]);
ASSERT_EQ('0', buf[1]);
ASSERT_EQ('1', buf[2]);
ASSERT_EQ('2', buf[3]);
ASSERT_EQ('3', buf[4]);
ASSERT_EQ('4', buf[5]);
ASSERT_EQ('5', buf[6]);
ASSERT_EQ('6', buf[7]);
ASSERT_EQ('7', buf[8]);
ASSERT_EQ('\0', buf[9]);
}
TEST(Fortify1, strncat6) {
char buf[10];
memset(buf, 'A', sizeof(buf));
buf[0] = 'a';
buf[1] = '\0';
char* res = __strncat_chk(buf, "01234567", 9, sizeof(buf));
ASSERT_EQ(buf, res);
ASSERT_EQ('a', buf[0]);
ASSERT_EQ('0', buf[1]);
ASSERT_EQ('1', buf[2]);
ASSERT_EQ('2', buf[3]);
ASSERT_EQ('3', buf[4]);
ASSERT_EQ('4', buf[5]);
ASSERT_EQ('5', buf[6]);
ASSERT_EQ('6', buf[7]);
ASSERT_EQ('7', buf[8]);
ASSERT_EQ('\0', buf[9]);
}
TEST(Fortify1, strcat) {
char buf[10];
memset(buf, 'A', sizeof(buf));
buf[0] = 'a';
buf[1] = '\0';
char* res = __strcat_chk(buf, "01234", sizeof(buf));
ASSERT_EQ(buf, res);
ASSERT_EQ('a', buf[0]);
ASSERT_EQ('0', buf[1]);
ASSERT_EQ('1', buf[2]);
ASSERT_EQ('2', buf[3]);
ASSERT_EQ('3', buf[4]);
ASSERT_EQ('4', buf[5]);
ASSERT_EQ('\0', buf[6]);
ASSERT_EQ('A', buf[7]);
ASSERT_EQ('A', buf[8]);
ASSERT_EQ('A', buf[9]);
}
TEST(Fortify1, strcat2) {
char buf[10];
memset(buf, 'A', sizeof(buf));
buf[0] = 'a';
buf[1] = '\0';
char* res = __strcat_chk(buf, "01234567", sizeof(buf));
ASSERT_EQ(buf, res);
ASSERT_EQ('a', buf[0]);
ASSERT_EQ('0', buf[1]);
ASSERT_EQ('1', buf[2]);
ASSERT_EQ('2', buf[3]);
ASSERT_EQ('3', buf[4]);
ASSERT_EQ('4', buf[5]);
ASSERT_EQ('5', buf[6]);
ASSERT_EQ('6', buf[7]);
ASSERT_EQ('7', buf[8]);
ASSERT_EQ('\0', buf[9]);
}