Re: [PATCH v3] ARM: traps: Implement KCFI trap handler for ARM32
Karl Mehltretter <[email protected]> Mon, 27 Jul 2026 02:10:19 +0200
| Newsgroups | org.kernel.vger.linux-hardening,dev.linux.lists.llvm,org.infradead.lists.linux-arm-kernel,org.kernel.vger.linux-kernel |
|---|---|
| Message-ID | <[email protected]> |
On Wed, Jul 15, 2026 at 10:52:27AM +0100, Kees Cook wrote:
> +bool arm_cfi_handle_failure(struct pt_regs *regs, enum bug_trap_type type)
> +{
> + switch (type) {
> + case BUG_TRAP_TYPE_BUG:
> + die("Oops - CFI", regs, 0);
> + break;
> + case BUG_TRAP_TYPE_WARN:
> + /* Permissive mode: skip the trapping instruction and continue. */
> + instruction_pointer(regs) += 4;
> + break;
On Thumb-2, Clang emits a 16-bit BKPT for CFI checks.
This skips the following Thumb instruction.
Thanks,
Karl