Merge tag 'hardening-v6.9-rc5' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux

Pull hardening fixes from Kees Cook:

 - Correctly disable UBSAN configs in configs/hardening (Nathan
   Chancellor)

 - Add missing signed integer overflow trap types to arm64 handler

* tag 'hardening-v6.9-rc5' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux:
  ubsan: Add awareness of signed integer overflow traps
  configs/hardening: Disable CONFIG_UBSAN_SIGNED_WRAP
  configs/hardening: Fix disabling UBSAN configurations

Author: torvalds

kernel/configs/hardening.config

@@ -39,11 +39,12 @@ CONFIG_UBSAN=y
 CONFIG_UBSAN_TRAP=y
 CONFIG_UBSAN_BOUNDS=y
 # CONFIG_UBSAN_SHIFT is not set
-# CONFIG_UBSAN_DIV_ZERO
-# CONFIG_UBSAN_UNREACHABLE
-# CONFIG_UBSAN_BOOL
-# CONFIG_UBSAN_ENUM
-# CONFIG_UBSAN_ALIGNMENT
+# CONFIG_UBSAN_DIV_ZERO is not set
+# CONFIG_UBSAN_UNREACHABLE is not set
+# CONFIG_UBSAN_SIGNED_WRAP is not set
+# CONFIG_UBSAN_BOOL is not set
+# CONFIG_UBSAN_ENUM is not set
+# CONFIG_UBSAN_ALIGNMENT is not set
 
 # Sampling-based heap out-of-bounds and use-after-free detection.
 CONFIG_KFENCE=y

lib/ubsan.c

@@ -44,9 +44,10 @@ const char *report_ubsan_failure(struct pt_regs *regs, u32 check_type)
 	case ubsan_shift_out_of_bounds:
 		return "UBSAN: shift out of bounds";
 #endif
-#ifdef CONFIG_UBSAN_DIV_ZERO
+#if defined(CONFIG_UBSAN_DIV_ZERO) || defined(CONFIG_UBSAN_SIGNED_WRAP)
 	/*
-	 * SanitizerKind::IntegerDivideByZero emits
+	 * SanitizerKind::IntegerDivideByZero and
+	 * SanitizerKind::SignedIntegerOverflow emit
 	 * SanitizerHandler::DivremOverflow.
 	 */
 	case ubsan_divrem_overflow:
@@ -77,6 +78,19 @@ const char *report_ubsan_failure(struct pt_regs *regs, u32 check_type)
 		return "UBSAN: alignment assumption";
 	case ubsan_type_mismatch:
 		return "UBSAN: type mismatch";
+#endif
+#ifdef CONFIG_UBSAN_SIGNED_WRAP
+	/*
+	 * SanitizerKind::SignedIntegerOverflow emits
+	 * SanitizerHandler::AddOverflow, SanitizerHandler::SubOverflow,
+	 * or SanitizerHandler::MulOverflow.
+	 */
+	case ubsan_add_overflow:
+		return "UBSAN: integer addition overflow";
+	case ubsan_sub_overflow:
+		return "UBSAN: integer subtraction overflow";
+	case ubsan_mul_overflow:
+		return "UBSAN: integer multiplication overflow";
 #endif
 	default:
 		return "UBSAN: unrecognized failure code";