linux-kernel - [PATCH 1/3] ARM: fix kasan link failures

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Date:   Wed,  3 Jul 2019 22:54:36 +0200
From:   Arnd Bergmann <arnd@...db.de>
To:     Florian Fainelli <f.fainelli@...il.com>
Cc:     Andrey Ryabinin <aryabinin@...tuozzo.com>,
        Abbott Liu <liuwenliang@...wei.com>,
        linux-arm-kernel@...ts.infradead.org, kasan-dev@...glegroups.com,
        Linus Walleij <linus.walleij@...aro.org>,
        Arnd Bergmann <arnd@...db.de>,
        Ard Biesheuvel <ard.biesheuvel@...aro.org>,
        Nicolas Pitre <nico@...xnic.net>,
        Stefan Agner <stefan@...er.ch>,
        Nathan Chancellor <natechancellor@...il.com>,
        Masahiro Yamada <yamada.masahiro@...ionext.com>,
        linux-kernel@...r.kernel.org, linux-efi@...r.kernel.org
Subject: [PATCH 1/3] ARM: fix kasan link failures

Getting the redirects for memcpy/memmove/memset functions right
in the decompressor and the efi stub is a bit tricky. Originally
these were meant to prevent the kasan code from calling itself
recursively. The decompressor is built without kasan but uses
the same redirects when CONFIG_KASAN is enabled, except in a few
cases that now cause link failures:

arch/arm/boot/compressed/fdt_rw.o: In function `fdt_set_name':
fdt_rw.c:(.text+0x3d4): undefined reference to `memcpy'
arch/arm/boot/compressed/fdt_rw.o: In function `fdt_add_property_':
fdt_rw.c:(.text+0x121c): undefined reference to `memmove'
arch/arm/boot/compressed/fdt_rw.o: In function `fdt_splice_':
fdt_rw.c:(.text+0x1460): undefined reference to `memmove'
arch/arm/boot/compressed/fdt_ro.o: In function `fdt_get_path':
fdt_ro.c:(.text+0x1384): undefined reference to `memcpy'
arch/arm/boot/compressed/fdt_wip.o: In function `fdt_setprop_inplace_namelen_partial':
fdt_wip.c:(.text+0x48): undefined reference to `memcpy'
arch/arm/boot/compressed/fdt_wip.o: In function `fdt_setprop_inplace':
fdt_wip.c:(.text+0x100): undefined reference to `memcpy'
arch/arm/boot/compressed/fdt.o: In function `fdt_move':
fdt.c:(.text+0xa04): undefined reference to `memmove'
arch/arm/boot/compressed/atags_to_fdt.o: In function `atags_to_fdt':
atags_to_fdt.c:(.text+0x404): undefined reference to `memcpy'
atags_to_fdt.c:(.text+0x450): undefined reference to `memcpy'

I tried to make everything use them, but ran into other problems:

drivers/firmware/efi/libstub/lib-fdt_sw.stub.o: In function `fdt_create_with_flags':
fdt_sw.c:(.text+0x34): undefined reference to `__memset'
arch/arm/boot/compressed/decompress.o: In function `lzo1x_decompress_safe':
decompress.c:(.text+0x290): undefined reference to `__memset'

This makes all the early boot code not use the redirects, which
works because we don't sanitize that code.

Setting -D__SANITIZE_ADDRESS__ is a bit confusing here, but it
does the trick.

Signed-off-by: Arnd Bergmann <arnd@...db.de>
---
 arch/arm/boot/compressed/Makefile     | 1 +
 arch/arm/boot/compressed/decompress.c | 2 --
 arch/arm/boot/compressed/libfdt_env.h | 2 --
 drivers/firmware/efi/libstub/Makefile | 3 ++-
 4 files changed, 3 insertions(+), 5 deletions(-)

diff --git a/arch/arm/boot/compressed/Makefile b/arch/arm/boot/compressed/Makefile
index dcc27fb24fbb..d91c2ded0e3d 100644
--- a/arch/arm/boot/compressed/Makefile
+++ b/arch/arm/boot/compressed/Makefile
@@ -25,6 +25,7 @@ endif
 
 GCOV_PROFILE		:= n
 KASAN_SANITIZE		:= n
+CFLAGS_KERNEL += -D__SANITIZE_ADDRESS__
 
 # Prevents link failures: __sanitizer_cov_trace_pc() is not linked in.
 KCOV_INSTRUMENT		:= n
diff --git a/arch/arm/boot/compressed/decompress.c b/arch/arm/boot/compressed/decompress.c
index 3794fae5f818..aa075d8372ea 100644
--- a/arch/arm/boot/compressed/decompress.c
+++ b/arch/arm/boot/compressed/decompress.c
@@ -47,10 +47,8 @@ extern char * strchrnul(const char *, int);
 #endif
 
 #ifdef CONFIG_KERNEL_XZ
-#ifndef CONFIG_KASAN
 #define memmove memmove
 #define memcpy memcpy
-#endif
 #include "../../../../lib/decompress_unxz.c"
 #endif
 
diff --git a/arch/arm/boot/compressed/libfdt_env.h b/arch/arm/boot/compressed/libfdt_env.h
index 8091efc21407..b36c0289a308 100644
--- a/arch/arm/boot/compressed/libfdt_env.h
+++ b/arch/arm/boot/compressed/libfdt_env.h
@@ -19,6 +19,4 @@ typedef __be64 fdt64_t;
 #define fdt64_to_cpu(x)		be64_to_cpu(x)
 #define cpu_to_fdt64(x)		cpu_to_be64(x)
 
-#undef memset
-
 #endif
diff --git a/drivers/firmware/efi/libstub/Makefile b/drivers/firmware/efi/libstub/Makefile
index 0460c7581220..fd1d72ea04dd 100644
--- a/drivers/firmware/efi/libstub/Makefile
+++ b/drivers/firmware/efi/libstub/Makefile
@@ -20,7 +20,8 @@ cflags-$(CONFIG_ARM64)		:= $(subst $(CC_FLAGS_FTRACE),,$(KBUILD_CFLAGS)) \
 				   -fpie $(DISABLE_STACKLEAK_PLUGIN)
 cflags-$(CONFIG_ARM)		:= $(subst $(CC_FLAGS_FTRACE),,$(KBUILD_CFLAGS)) \
 				   -fno-builtin -fpic \
-				   $(call cc-option,-mno-single-pic-base)
+				   $(call cc-option,-mno-single-pic-base) \
+				   -D__SANITIZE_ADDRESS__
 
 cflags-$(CONFIG_EFI_ARMSTUB)	+= -I$(srctree)/scripts/dtc/libfdt
 
-- 
2.20.0