Symposium sur la sécurité des technologies de l'information et des communications

The C language has historically suffered from a lack of proper bounds-checking on all kinds of arrays. The Kernel Self-Protection Project has been addressing this issue for several years. In this presentation, we will learn about the most recent hardening efforts to resolve the problem of bounds-checking, particularly for fixed-size and flexible arrays.

We will explore the different mechanisms being used to harden key APIs like memcpy() against buffer overflows, which includes the use of some interesting built-in compiler functions. We will also talk about a couple of recent compiler options like -fstrict-flex-arrays and -Wflex-array-member-not-at-end, as well as the new __counted_by__ attribute released in Clang-18 a few weeks ago, which helps us gain run-time bounds-checking coverage on flexible arrays.

Overall, we will discuss how various challenges have been overcome and highlight the innovations developed to solve the problem of array bounds-checking in both C and the Linux kernel once and for all.