linux-hardening - [PATCH] ubsan: Add awareness of signed integer overflow traps

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Date: Mon, 15 Apr 2024 11:28:35 -0700
From: Kees Cook <keescook@...omium.org>
To: Marco Elver <elver@...gle.com>
Cc: Kees Cook <keescook@...omium.org>,
	Nathan Chancellor <nathan@...nel.org>,
	Justin Stitt <justinstitt@...gle.com>,
	Andrey Konovalov <andreyknvl@...il.com>,
	Andrey Ryabinin <ryabinin.a.a@...il.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	kasan-dev@...glegroups.com,
	linux-hardening@...r.kernel.org,
	Nick Desaulniers <ndesaulniers@...gle.com>,
	Bill Wendling <morbo@...gle.com>,
	linux-kernel@...r.kernel.org,
	llvm@...ts.linux.dev
Subject: [PATCH] ubsan: Add awareness of signed integer overflow traps

On arm64, UBSAN traps can be decoded from the trap instruction. Add the
add, sub, and mul overflow trap codes now that CONFIG_UBSAN_SIGNED_WRAP
exists. Seen under clang 19:

  Internal error: UBSAN: unrecognized failure code: 00000000f2005515 [#1] PREEMPT SMP

Reported-by: Nathan Chancellor <nathan@...nel.org>
Closes: https://lore.kernel.org/lkml/20240411-fix-ubsan-in-hardening-config-v1-0-e0177c80ffaa@kernel.org
Fixes: 557f8c582a9b ("ubsan: Reintroduce signed overflow sanitizer")
Signed-off-by: Kees Cook <keescook@...omium.org>
---
Cc: Marco Elver <elver@...gle.com>
Cc: Justin Stitt <justinstitt@...gle.com>
Cc: Andrey Konovalov <andreyknvl@...il.com>
Cc: Andrey Ryabinin <ryabinin.a.a@...il.com>
Cc: Andrew Morton <akpm@...ux-foundation.org>
Cc: kasan-dev@...glegroups.com
Cc: linux-hardening@...r.kernel.org
---
 lib/ubsan.c | 18 ++++++++++++++++--
 1 file changed, 16 insertions(+), 2 deletions(-)

diff --git a/lib/ubsan.c b/lib/ubsan.c
index 5fc107f61934..ad32beb8c058 100644
--- a/lib/ubsan.c
+++ b/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_INTEGER_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_INTEGER_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";
-- 
2.34.1