linux-hardening - [PATCH AUTOSEL 6.9 13/15] ubsan: Avoid i386 UBSAN handler crashes with Clang

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Message-ID: <20240526094152.3412316-13-sashal@kernel.org>
Date: Sun, 26 May 2024 05:41:45 -0400
From: Sasha Levin <sashal@...nel.org>
To: linux-kernel@...r.kernel.org,
	stable@...r.kernel.org
Cc: Kees Cook <keescook@...omium.org>,
	Erhard Furtner <erhard_f@...lbox.org>,
	Nathan Chancellor <nathan@...nel.org>,
	Justin Stitt <justinstitt@...gle.com>,
	Sasha Levin <sashal@...nel.org>,
	kasan-dev@...glegroups.com,
	linux-hardening@...r.kernel.org,
	llvm@...ts.linux.dev
Subject: [PATCH AUTOSEL 6.9 13/15] ubsan: Avoid i386 UBSAN handler crashes with Clang

From: Kees Cook <keescook@...omium.org>

[ Upstream commit 2e431b23a13ce4459cf484c8f0b3218c7048b515 ]

When generating Runtime Calls, Clang doesn't respect the -mregparm=3
option used on i386. Hopefully this will be fixed correctly in Clang 19:
https://github.com/llvm/llvm-project/pull/89707
but we need to fix this for earlier Clang versions today. Force the
calling convention to use non-register arguments.

Reported-by: Erhard Furtner <erhard_f@...lbox.org>
Closes: https://github.com/KSPP/linux/issues/350
Link: https://lore.kernel.org/r/20240424224026.it.216-kees@kernel.org
Acked-by: Nathan Chancellor <nathan@...nel.org>
Acked-by: Justin Stitt <justinstitt@...gle.com>
Signed-off-by: Kees Cook <keescook@...omium.org>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 lib/ubsan.h | 41 +++++++++++++++++++++++++++--------------
 1 file changed, 27 insertions(+), 14 deletions(-)

diff --git a/lib/ubsan.h b/lib/ubsan.h
index 0abbbac8700d1..0982578fbd98f 100644
--- a/lib/ubsan.h
+++ b/lib/ubsan.h
@@ -124,19 +124,32 @@ typedef s64 s_max;
 typedef u64 u_max;
 #endif
 
-void __ubsan_handle_add_overflow(void *data, void *lhs, void *rhs);
-void __ubsan_handle_sub_overflow(void *data, void *lhs, void *rhs);
-void __ubsan_handle_mul_overflow(void *data, void *lhs, void *rhs);
-void __ubsan_handle_negate_overflow(void *_data, void *old_val);
-void __ubsan_handle_divrem_overflow(void *_data, void *lhs, void *rhs);
-void __ubsan_handle_type_mismatch(struct type_mismatch_data *data, void *ptr);
-void __ubsan_handle_type_mismatch_v1(void *_data, void *ptr);
-void __ubsan_handle_out_of_bounds(void *_data, void *index);
-void __ubsan_handle_shift_out_of_bounds(void *_data, void *lhs, void *rhs);
-void __ubsan_handle_builtin_unreachable(void *_data);
-void __ubsan_handle_load_invalid_value(void *_data, void *val);
-void __ubsan_handle_alignment_assumption(void *_data, unsigned long ptr,
-					 unsigned long align,
-					 unsigned long offset);
+/*
+ * When generating Runtime Calls, Clang doesn't respect the -mregparm=3
+ * option used on i386: https://github.com/llvm/llvm-project/issues/89670
+ * Fix this for earlier Clang versions by forcing the calling convention
+ * to use non-register arguments.
+ */
+#if defined(CONFIG_X86_32) && \
+    defined(CONFIG_CC_IS_CLANG) && CONFIG_CLANG_VERSION < 190000
+# define ubsan_linkage asmlinkage
+#else
+# define ubsan_linkage
+#endif
+
+void ubsan_linkage __ubsan_handle_add_overflow(void *data, void *lhs, void *rhs);
+void ubsan_linkage __ubsan_handle_sub_overflow(void *data, void *lhs, void *rhs);
+void ubsan_linkage __ubsan_handle_mul_overflow(void *data, void *lhs, void *rhs);
+void ubsan_linkage __ubsan_handle_negate_overflow(void *_data, void *old_val);
+void ubsan_linkage __ubsan_handle_divrem_overflow(void *_data, void *lhs, void *rhs);
+void ubsan_linkage __ubsan_handle_type_mismatch(struct type_mismatch_data *data, void *ptr);
+void ubsan_linkage __ubsan_handle_type_mismatch_v1(void *_data, void *ptr);
+void ubsan_linkage __ubsan_handle_out_of_bounds(void *_data, void *index);
+void ubsan_linkage __ubsan_handle_shift_out_of_bounds(void *_data, void *lhs, void *rhs);
+void ubsan_linkage __ubsan_handle_builtin_unreachable(void *_data);
+void ubsan_linkage __ubsan_handle_load_invalid_value(void *_data, void *val);
+void ubsan_linkage __ubsan_handle_alignment_assumption(void *_data, unsigned long ptr,
+						       unsigned long align,
+						       unsigned long offset);
 
 #endif
-- 
2.43.0