[Devel] [PATCH RHEL7 COMMIT] ms/x86, efi, kasan: #undef memset/memcpy/memmove per arch

[Konstantin Khorenko]

The commit is pushed to "branch-rh7-3.10.0-693.1.1.vz7.37.x-ovz" and will appear at https://src.openvz.org/scm/ovz/vzkernel.git
after rh7-3.10.0-693.1.1.el7
------>
commit f4b5ab2e530bf8bc46c79d4effa14e51a6643e69
Author: Andrey Ryabinin <ryabinin.a.a at gmail.com>
Date:   Mon Aug 28 15:57:45 2017 +0300

    ms/x86, efi, kasan: #undef memset/memcpy/memmove per arch
    
    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 2215cd2..8e70dd8 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;