Tools for testing and debugging memory issues (part 1)

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Memory safety
Toolchain
AddressSanitizer (ASan)
Questions

This lesson contains approximately 35 minutes of video content.

Memory safety

Toolchain

AddressSanitizer (ASan)

Clang-14 and debugging symbols

When compiling by hand, you'd include -g to have the compiler write debugging symbols. For the version of clang++ that we're using (v. 14.0.5), DWARFv5 debug format is used by default. Unfortunately, some of our tools will not properly read the DWARF5 generated by clang-14. Therefore, instead of using the -g flag, use -gdwarf-4.

Questions

QTools for Testing and Debugging Q1

This question is ungraded.

Which of the following statements is incorrect?

A memory leak is problematic because it causes memory usage to balloon while the program is running.

Dereferencing the nullptr results in well-defined behavior.

You should be careful about array bounds when indexing into an array.

You shouldn’t access memory after it has been deallocated since a write might get lost, and a read possibly garbage.

Practice question: try as many times as you like

QTools for Testing and Debugging Q2

This question is ungraded.

Given the following code snippet,

char input[6];
std::cin >> input;
std::cout << input << std::endl;

Of the strings below, which is most likely to cause a segmentation fault if read from standard input into input?

`123`

`Hello World`

`Howdy`

`Texas_A&M_University`

Practice question: try as many times as you like

QTools for Testing and Debugging Q3

This question is ungraded.

Of the following statements, three describe programmatic actions/operations that can cause runtime issues, while one is entirely safe. Select the safe statement.

After deallocating a dynamically allocated memory, assign the pointer that once pointed to the dynamically allocated object the nullptr.

An off-by-one error while indexing into an array.

Forgetting to return a value in a value-returning function.

Interacting with an uninitialized or otherwise invalid pointer.

Practice question: try as many times as you like