linux-kernel - [PATCH v6 03/29] vmlinux.lds.h: Avoid KASAN and KCSAN's unwanted sections

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Date:   Fri, 21 Aug 2020 12:42:44 -0700
From:   Kees Cook <keescook@...omium.org>
To:     Ingo Molnar <mingo@...nel.org>
Cc:     Kees Cook <keescook@...omium.org>, Marco Elver <elver@...gle.com>,
        Catalin Marinas <catalin.marinas@....com>,
        Mark Rutland <mark.rutland@....com>,
        Ard Biesheuvel <ardb@...nel.org>,
        Peter Collingbourne <pcc@...gle.com>,
        James Morse <james.morse@....com>,
        Borislav Petkov <bp@...e.de>, Ingo Molnar <mingo@...hat.com>,
        Russell King <linux@...linux.org.uk>,
        Masahiro Yamada <masahiroy@...nel.org>,
        Arvind Sankar <nivedita@...m.mit.edu>,
        Nick Desaulniers <ndesaulniers@...gle.com>,
        Nathan Chancellor <natechancellor@...il.com>,
        Arnd Bergmann <arnd@...db.de>, x86@...nel.org,
        clang-built-linux@...glegroups.com, linux-arch@...r.kernel.org,
        linux-efi@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-kernel@...r.kernel.org
Subject: [PATCH v6 03/29] vmlinux.lds.h: Avoid KASAN and KCSAN's unwanted sections

KASAN (-fsanitize=kernel-address) and KCSAN (-fsanitize=thread)
produce unwanted[1] .eh_frame and .init_array.* sections. Add them to
COMMON_DISCARDS, except with CONFIG_CONSTRUCTORS, which wants to keep
.init_array.* sections.

[1] https://bugs.llvm.org/show_bug.cgi?id=46478

Tested-by: Marco Elver <elver@...gle.com>
Signed-off-by: Kees Cook <keescook@...omium.org>
---
 include/asm-generic/vmlinux.lds.h | 20 ++++++++++++++++++++
 1 file changed, 20 insertions(+)

diff --git a/include/asm-generic/vmlinux.lds.h b/include/asm-generic/vmlinux.lds.h
index f1f02a2f71b7..6b89a03e636e 100644
--- a/include/asm-generic/vmlinux.lds.h
+++ b/include/asm-generic/vmlinux.lds.h
@@ -954,7 +954,27 @@
 	EXIT_DATA
 #endif
 
+/*
+ * Clang's -fsanitize=kernel-address and -fsanitize=thread produce
+ * unwanted sections (.eh_frame and .init_array.*), but
+ * CONFIG_CONSTRUCTORS wants to keep any .init_array.* sections.
+ * https://bugs.llvm.org/show_bug.cgi?id=46478
+ */
+#if defined(CONFIG_KASAN_GENERIC) || defined(CONFIG_KCSAN)
+# ifdef CONFIG_CONSTRUCTORS
+#  define SANITIZER_DISCARDS						\
+	*(.eh_frame)
+# else
+#  define SANITIZER_DISCARDS						\
+	*(.init_array) *(.init_array.*)					\
+	*(.eh_frame)
+# endif
+#else
+# define SANITIZER_DISCARDS
+#endif
+
 #define COMMON_DISCARDS							\
+	SANITIZER_DISCARDS						\
 	*(.discard)							\
 	*(.discard.*)							\
 	*(.modinfo)							\
-- 
2.25.1