On Wed, 29 May 2024 at 04:20, Gatlin Newhouse <gatlin.newho...@gmail.com> wrote:
[...]
> if (regs->flags & X86_EFLAGS_IF)
> raw_local_irq_enable();
> - if (report_bug(regs->ip, regs) == BUG_TRAP_TYPE_WARN ||
> - handle_cfi_failure(regs) == BUG_TRAP_TYPE_WARN) {
> - regs->ip += LEN_UD2;
> - handled = true;
> +
> + if (insn == INSN_UD2) {
> + if (report_bug(regs->ip, regs) == BUG_TRAP_TYPE_WARN ||
> + handle_cfi_failure(regs) == BUG_TRAP_TYPE_WARN) {
> + regs->ip += LEN_UD2;
> + handled = true;
> + }
> + } else {
> + if (handle_ubsan_failure(regs, insn) == BUG_TRAP_TYPE_WARN) {
handle_ubsan_failure currently only returns BUG_TRAP_TYPE_NONE?
> + if (insn == INSN_REX)
> + regs->ip += LEN_REX;
> + regs->ip += LEN_UD1;
> + handled = true;
> + }
> }
> if (regs->flags & X86_EFLAGS_IF)
> raw_local_irq_disable();
> diff --git a/arch/x86/kernel/ubsan.c b/arch/x86/kernel/ubsan.c
> new file mode 100644
> index 000000000000..6cae11f4fe23
> --- /dev/null
> +++ b/arch/x86/kernel/ubsan.c
> @@ -0,0 +1,32 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Clang Undefined Behavior Sanitizer trap mode support.
> + */
> +#include <linux/bug.h>
> +#include <linux/string.h>
> +#include <linux/printk.h>
> +#include <linux/ubsan.h>
> +#include <asm/ptrace.h>
> +#include <asm/ubsan.h>
> +
> +/*
> + * Checks for the information embedded in the UD1 trap instruction
> + * for the UB Sanitizer in order to pass along debugging output.
> + */
> +enum bug_trap_type handle_ubsan_failure(struct pt_regs *regs, int insn)
> +{
> + u32 type = 0;
> +
> + if (insn == INSN_REX) {
> + type = (*(u16 *)(regs->ip + LEN_REX + LEN_UD1));
> + if ((type & 0xFF) == 0x40)
> + type = (type >> 8) & 0xFF;
> + } else {
> + type = (*(u16 *)(regs->ip + LEN_UD1));
> + if ((type & 0xFF) == 0x40)
> + type = (type >> 8) & 0xFF;
> + }
> + pr_crit("%s at %pS\n", report_ubsan_failure(regs, type), (void
> *)regs->ip);
> +
> + return BUG_TRAP_TYPE_NONE;
> +}
Shouldn't this return BUG_TRAP_TYPE_WARN?
