fix(asan): heap-use-after-free caused by using string_view in fail_point

[foreverneverer]

Problem

It will crash because of heap-use-after-free when execute dsn::fail::cfg("db_write_batch_put", "10%return()") in test_batch_writes of pegasus_server_write_test.cpp. The code of pegasus_server is test_batch_writes:

void test_batch_writes()
    {
        dsn::fail::setup();

        dsn::fail::cfg("db_write_batch_put", "10%return()");
        dsn::fail::cfg("db_write_batch_remove", "10%return()");
        dsn::fail::cfg("db_write", "10%return()");
....
    }

Reason

The code call(line 107):

rdsn/src/core/core/fail_point.cpp

Lines 105 to 107 in a0ecf81

	sub_match = match[3];
	string_view task_type = sub_match.str();
	if (task_type.compare("off") == 0) {

and crash at(line 353):

rdsn/include/dsn/utility/string_view.h

Lines 349 to 353 in a0ecf81

	int compare(string_view x) const noexcept
	{
	auto min_length = std::min(length_, x.length_);
	if (min_length > 0) {
	int r = memcmp(ptr_, x.ptr_, min_length);

The root causes have two aspect:

• The string_view class has char * member, but only support shallow copying
• sub_match.str() will generate temporary variable and use this temporary variable to construct the string_view

The actions just as follow:

std::string temp = sub_match.str();
string_view task_type(temp)
// then `temp` will be freed and the `const char *ptr_`  of  the `temp` will be also freed
 memcmp(ptr_, x.ptr_, min_length);// crash here because "ptr_" was freed. line 353 of string_view.h

Solution

The usage of string_view isn't right, we can use std::string