From b65413768abd27a55af74945aec58127a52b30a8 Mon Sep 17 00:00:00 2001 From: Masami Hiramatsu Date: Tue, 11 Jul 2023 10:50:58 +0900 Subject: x86/kprobes: Prohibit probing on compiler generated CFI checking code MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Prohibit probing on the compiler generated CFI typeid checking code because it is used for decoding typeid when CFI error happens. The compiler generates the following instruction sequence for indirect call checks on x86;   movl -, %r10d ; 6 bytes addl -4(%reg), %r10d ; 4 bytes je .Ltmp1 ; 2 bytes ud2 ; <- regs->ip And handle_cfi_failure() decodes these instructions (movl and addl) for the typeid and the target address. Thus if we put a kprobe on those instructions, the decode will fail and report a wrong typeid and target address. Signed-off-by: Masami Hiramatsu (Google) Signed-off-by: Peter Zijlstra (Intel) Link: https://lore.kernel.org/r/168904025785.116016.12766408611437534723.stgit@devnote2 --- include/linux/cfi.h | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) (limited to 'include/linux/cfi.h') diff --git a/include/linux/cfi.h b/include/linux/cfi.h index 5e134f4ce8b7..3552ec82b725 100644 --- a/include/linux/cfi.h +++ b/include/linux/cfi.h @@ -19,11 +19,13 @@ static inline enum bug_trap_type report_cfi_failure_noaddr(struct pt_regs *regs, { return report_cfi_failure(regs, addr, NULL, 0); } +#endif /* CONFIG_CFI_CLANG */ #ifdef CONFIG_ARCH_USES_CFI_TRAPS bool is_cfi_trap(unsigned long addr); +#else +static inline bool is_cfi_trap(unsigned long addr) { return false; } #endif -#endif /* CONFIG_CFI_CLANG */ #ifdef CONFIG_MODULES #ifdef CONFIG_ARCH_USES_CFI_TRAPS -- cgit v1.2.3-73-gaa49b