[Devel] [PATCH rh7 2/2] ms/x86, efi, kasan: #undef memset/memcpy/memmove per arch

[Andrey Ryabinin]

From: Andrey Ryabinin <ryabinin.a.a at gmail.com>

commit 769a8089c1fd2fe94c13e66fe6e03d7820953ee3 upstream.

In not-instrumented code KASAN replaces instrumented memset/memcpy/memmove
with not-instrumented analogues __memset/__memcpy/__memove.

However, on x86 the EFI stub is not linked with the kernel.  It uses
not-instrumented mem*() functions from arch/x86/boot/compressed/string.c

So we don't replace them with __mem*() variants in EFI stub.

On ARM64 the EFI stub is linked with the kernel, so we should replace
mem*() functions with __mem*(), because the EFI stub runs before KASAN
sets up early shadow.

So let's move these #undef mem* into arch's asm/efi.h which is also
included by the EFI stub.

Also, this will fix the warning in 32-bit build reported by kbuild test
robot:

	efi-stub-helper.c:599:2: warning: implicit declaration of function 'memcpy'

[akpm at linux-foundation.org: use 80 cols in comment]
Signed-off-by: Andrey Ryabinin <ryabinin.a.a at gmail.com>
Reported-by: Fengguang Wu <fengguang.wu at gmail.com>
Cc: Will Deacon <will.deacon at arm.com>
Cc: Catalin Marinas <catalin.marinas at arm.com>
Cc: Matt Fleming <matt.fleming at intel.com>
Cc: Thomas Gleixner <tglx at linutronix.de>
Cc: Ingo Molnar <mingo at redhat.com>
Cc: "H. Peter Anvin" <hpa at zytor.com>
Signed-off-by: Andrew Morton <akpm at linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds at linux-foundation.org>
Signed-off-by: Andrey Ryabinin <aryabinin at virtuozzo.com>
---
 arch/x86/include/asm/efi.h | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/arch/x86/include/asm/efi.h b/arch/x86/include/asm/efi.h
index 2215cd26512d..8e70dd8bde6c 100644
--- a/arch/x86/include/asm/efi.h
+++ b/arch/x86/include/asm/efi.h
@@ -68,6 +68,16 @@ extern u64 asmlinkage efi_call(void *fp, ...);
 extern void __iomem *efi_ioremap(unsigned long addr, unsigned long size,
 				 u32 type, u64 attribute);
 
+/*
+ * CONFIG_KASAN may redefine memset to __memset.  __memset function is present
+ * only in kernel binary.  Since the EFI stub linked into a separate binary it
+ * doesn't have __memset().  So we should use standard memset from
+ * arch/x86/boot/compressed/string.c.  The same applies to memcpy and memmove.
+ */
+#undef memcpy
+#undef memset
+#undef memmove
+
 #endif /* CONFIG_X86_32 */
 
 extern int add_efi_memmap;
-- 
2.13.5