kasan: fix hwasan build for gcc

PATCH Applied Arnd Bergmann 4 participants 4 messages Mar 23, 2021 – Mar 30, 2021

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Arnd Bergmann

author

2021-03-23 12:42 UTC #0 lore raw

PATCH 1/1 kasan: fix hwasan build for gcc

From: Arnd Bergmann <[email protected]>

gcc-11 adds support for -fsanitize=kernel-hwaddress, so it becomes possible to enable CONFIG_KASAN_SW_TAGS.

Unfortunately this fails to build at the moment, because the corresponding command line arguments use llvm specific syntax.

Change it to use the cc-param macro instead, which works on both clang and gcc.

Signed-off-by Arnd Bergmann <[email protected]>

---
 scripts/Makefile.kasan | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

scripts/Makefile.kasan +4 -4

index 1e000cc2e7b4..0a2789783d1b 100644
@@ -36,14 +36,14 @@ endif # CONFIG_KASAN_GENERIC
 ifdef CONFIG_KASAN_SW_TAGS
 
 ifdef CONFIG_KASAN_INLINE
-    instrumentation_flags := -mllvm -hwasan-mapping-offset=$(KASAN_SHADOW_OFFSET)
+    instrumentation_flags := $(call cc-param,hwasan-mapping-offset=$(KASAN_SHADOW_OFFSET))
 else
-    instrumentation_flags := -mllvm -hwasan-instrument-with-calls=1
+    instrumentation_flags := $(call cc-param,hwasan-instrument-with-calls=1)
 endif
 
 CFLAGS_KASAN := -fsanitize=kernel-hwaddress \
-		-mllvm -hwasan-instrument-stack=$(CONFIG_KASAN_STACK) \
-		-mllvm -hwasan-use-short-granules=0 \
+		$(call cc-param,hwasan-instrument-stack=$(CONFIG_KASAN_STACK)) \
+		$(call cc-param,hwasan-use-short-granules=0) \
 		$(instrumentation_flags)
 
 endif # CONFIG_KASAN_SW_TAGS

Signature · 1 line

2.29.2

Andrew Morton

maintainer

2021-03-24 22:49 UTC #2 lore raw

Quoted 13 lines · On Tue, 23 Mar 2021 13:51:32 +0100 Marco Elver <[email protected]> wrote:

Quoted 12 lines · Arnd Bergmann
From: Arnd Bergmann <[email protected]>
gcc-11 adds support for -fsanitize=kernel-hwaddress, so it becomes possible to enable CONFIG_KASAN_SW_TAGS.
Unfortunately this fails to build at the moment, because the corresponding command line arguments use llvm specific syntax.
Change it to use the cc-param macro instead, which works on both clang and gcc.

Quoted 6 lines

Quoted 1 line
Signed-off-by Arnd Bergmann <[email protected]>
Reviewed-by Marco Elver <[email protected]>
Although I think you need to rebase against either -mm or -next, because there have been changes to the CONFIG_KASAN_STACK variable.

This fix is applicable to 5.12, so it's better than the 5.13 patches in -mm be changed to accomodate this patch.

afaict the only needed change was to update kasan-remove-redundant-config-option.patch as below. The scripts/Makefile.kasan part was changed:

@@ -42,7 +48,7 @@ else
endif

CFLAGS_KASAN := -fsanitize=kernel-hwaddress \
- $(call cc-param,hwasan-instrument-stack=$(CONFIG_KASAN_STACK)) \
+ $(call cc-param,hwasan-instrument-stack=$(stack_enable)) \
$(call cc-param,hwasan-use-short-granules=0) \
$(instrumentation_flags)

Whole patch:

arch/arm64/kernel/sleep.S renamed from arch/arm64/kernel/sleep.S~kasan-remove-redundant-config-option +1 -1

@@ -134,7 +134,7 @@ SYM_FUNC_START(_cpu_resume)
 	 */
 	bl	cpu_do_resume
 
-#if defined(CONFIG_KASAN) && CONFIG_KASAN_STACK
+#if defined(CONFIG_KASAN) && defined(CONFIG_KASAN_STACK)
 	mov	x0, sp
 	bl	kasan_unpoison_task_stack_below
 #endif

arch/x86/kernel/acpi/wakeup_64.S renamed from arch/x86/kernel/acpi/wakeup_64.S~kasan-remove-redundant-config-option +1 -1

@@ -115,7 +115,7 @@ SYM_FUNC_START(do_suspend_lowlevel)
 	movq	pt_regs_r14(%rax), %r14
 	movq	pt_regs_r15(%rax), %r15
 
-#if defined(CONFIG_KASAN) && CONFIG_KASAN_STACK
+#if defined(CONFIG_KASAN) && defined(CONFIG_KASAN_STACK)
 	/*
 	 * The suspend path may have poisoned some areas deeper in the stack,
 	 * which we now need to unpoison.

include/linux/kasan.h renamed from include/linux/kasan.h~kasan-remove-redundant-config-option +1 -1

@@ -330,7 +330,7 @@ static inline bool kasan_check_byte(cons
 
 #endif /* CONFIG_KASAN */
 
-#if defined(CONFIG_KASAN) && CONFIG_KASAN_STACK
+#if defined(CONFIG_KASAN) && defined(CONFIG_KASAN_STACK)
 void kasan_unpoison_task_stack(struct task_struct *task);
 #else
 static inline void kasan_unpoison_task_stack(struct task_struct *task) {}

lib/Kconfig.kasan renamed from lib/Kconfig.kasan~kasan-remove-redundant-config-option +3 -2

@@ -138,9 +138,10 @@ config KASAN_INLINE
 
 endchoice
 
-config KASAN_STACK_ENABLE
+config KASAN_STACK
 	bool "Enable stack instrumentation (unsafe)" if CC_IS_CLANG && !COMPILE_TEST
 	depends on KASAN_GENERIC || KASAN_SW_TAGS
+	default y if CC_IS_GCC
 	help
 	  The LLVM stack address sanitizer has a know problem that
 	  causes excessive stack usage in a lot of functions, see

@@ -155,7 +156,7 @@ config KASAN_STACK_ENABLE
 	  to use and enabled by default.
 
 config KASAN_STACK
-	int
+	bool
 	depends on KASAN_GENERIC || KASAN_SW_TAGS
 	default 1 if KASAN_STACK_ENABLE || CC_IS_GCC
 	default 0

mm/kasan/common.c renamed from mm/kasan/common.c~kasan-remove-redundant-config-option +1 -1

@@ -63,7 +63,7 @@ void __kasan_unpoison_range(const void *
 	kasan_unpoison(address, size);
 }
 
-#if CONFIG_KASAN_STACK
+#ifdef CONFIG_KASAN_STACK
 /* Unpoison the entire stack for a task. */
 void kasan_unpoison_task_stack(struct task_struct *task)
 {

mm/kasan/kasan.h renamed from mm/kasan/kasan.h~kasan-remove-redundant-config-option +1 -1

@@ -231,7 +231,7 @@ void *kasan_find_first_bad_addr(void *ad
 const char *kasan_get_bug_type(struct kasan_access_info *info);
 void kasan_metadata_fetch_row(char *buffer, void *row);
 
-#if defined(CONFIG_KASAN_GENERIC) && CONFIG_KASAN_STACK
+#if defined(CONFIG_KASAN_GENERIC) && defined(CONFIG_KASAN_STACK)
 void kasan_print_address_stack_frame(const void *addr);
 #else
 static inline void kasan_print_address_stack_frame(const void *addr) { }

mm/kasan/report_generic.c renamed from mm/kasan/report_generic.c~kasan-remove-redundant-config-option +1 -1

@@ -128,7 +128,7 @@ void kasan_metadata_fetch_row(char *buff
 	memcpy(buffer, kasan_mem_to_shadow(row), META_BYTES_PER_ROW);
 }
 
-#if CONFIG_KASAN_STACK
+#ifdef CONFIG_KASAN_STACK
 static bool __must_check tokenize_frame_descr(const char **frame_descr,
 					      char *token, size_t max_tok_len,
 					      unsigned long *value)

scripts/Makefile.kasan renamed from scripts/Makefile.kasan~kasan-remove-redundant-config-option +8 -2

@@ -2,6 +2,12 @@
 CFLAGS_KASAN_NOSANITIZE := -fno-builtin
 KASAN_SHADOW_OFFSET ?= $(CONFIG_KASAN_SHADOW_OFFSET)
 
+ifdef CONFIG_KASAN_STACK
+	stack_enable := 1
+else
+	stack_enable := 0
+endif
+
 ifdef CONFIG_KASAN_GENERIC
 
 ifdef CONFIG_KASAN_INLINE

@@ -27,7 +33,7 @@ else
 	CFLAGS_KASAN := $(CFLAGS_KASAN_SHADOW) \
 	 $(call cc-param,asan-globals=1) \
 	 $(call cc-param,asan-instrumentation-with-call-threshold=$(call_threshold)) \
-	 $(call cc-param,asan-stack=$(CONFIG_KASAN_STACK)) \
+	 $(call cc-param,asan-stack=$(stack_enable)) \
 	 $(call cc-param,asan-instrument-allocas=1)
 endif

@@ -42,7 +48,7 @@ else
 endif
 
 CFLAGS_KASAN := -fsanitize=kernel-hwaddress \
-		$(call cc-param,hwasan-instrument-stack=$(CONFIG_KASAN_STACK)) \
+		$(call cc-param,hwasan-instrument-stack=$(stack_enable)) \
 		$(call cc-param,hwasan-use-short-granules=0) \
 		$(instrumentation_flags)

security/Kconfig.hardening renamed from security/Kconfig.hardening~kasan-remove-redundant-config-option +2 -2

@@ -64,7 +64,7 @@ choice
 	config GCC_PLUGIN_STRUCTLEAK_BYREF
 		bool "zero-init structs passed by reference (strong)"
 		depends on GCC_PLUGINS
-		depends on !(KASAN && KASAN_STACK=1)
+		depends on !(KASAN && KASAN_STACK)
 		select GCC_PLUGIN_STRUCTLEAK
 		help
 		  Zero-initialize any structures on the stack that may

@@ -82,7 +82,7 @@ choice
 	config GCC_PLUGIN_STRUCTLEAK_BYREF_ALL
 		bool "zero-init anything passed by reference (very strong)"
 		depends on GCC_PLUGINS
-		depends on !(KASAN && KASAN_STACK=1)
+		depends on !(KASAN && KASAN_STACK)
 		select GCC_PLUGIN_STRUCTLEAK
 		help
 		  Zero-initialize any stack variables that may be passed

Andrey Konovalov

reviewer

2021-03-30 18:49 UTC #3 lore raw

In reply to Arnd Bergmann

Quoted 41 lines · Arnd Bergmann

From: Arnd Bergmann <[email protected]>

gcc-11 adds support for -fsanitize=kernel-hwaddress, so it becomes possible to enable CONFIG_KASAN_SW_TAGS.

Unfortunately this fails to build at the moment, because the corresponding command line arguments use llvm specific syntax.

Change it to use the cc-param macro instead, which works on both clang and gcc.

Signed-off-by Arnd Bergmann <[email protected]>

---
 scripts/Makefile.kasan | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

scripts/Makefile.kasan +4 -5

index 1e000cc2e7b4..0a2789783d1b 100644
@@ -36,14 +36,14 @@ endif # CONFIG_KASAN_GENERIC
 ifdef CONFIG_KASAN_SW_TAGS
 
 ifdef CONFIG_KASAN_INLINE
-    instrumentation_flags := -mllvm -hwasan-mapping-offset=$(KASAN_SHADOW_OFFSET)
+    instrumentation_flags := $(call cc-param,hwasan-mapping-offset=$(KASAN_SHADOW_OFFSET))
 else
-    instrumentation_flags := -mllvm -hwasan-instrument-with-calls=1
+    instrumentation_flags := $(call cc-param,hwasan-instrument-with-calls=1)
 endif
 
 CFLAGS_KASAN := -fsanitize=kernel-hwaddress \
-               -mllvm -hwasan-instrument-stack=$(CONFIG_KASAN_STACK) \
-               -mllvm -hwasan-use-short-granules=0 \
+               $(call cc-param,hwasan-instrument-stack=$(CONFIG_KASAN_STACK)) \
+               $(call cc-param,hwasan-use-short-granules=0) \
                $(instrumentation_flags)
 
 endif # CONFIG_KASAN_SW_TAGS
--

Quoted 2 lines

2.29.2

Hi Arnd,

This patch breaks SW_TAGS build with Clang for me with:

arch/arm64/include/asm/current.h:19: undefined reference to `__hwasan_tls'

The reason for this is that cc-param is only defined for KASAN_GENERIC, the definition needs to be moved.

Thanks!