From d6d51a96c7d63b7450860a3037f2d62388286a52 Mon Sep 17 00:00:00 2001 From: Linus Walleij Date: Sun, 25 Oct 2020 23:52:08 +0100 Subject: ARM: 9014/2: Replace string mem* functions for KASan Functions like memset()/memmove()/memcpy() do a lot of memory accesses. If a bad pointer is passed to one of these functions it is important to catch this. Compiler instrumentation cannot do this since these functions are written in assembly. KASan replaces these memory functions with instrumented variants. The original functions are declared as weak symbols so that the strong definitions in mm/kasan/kasan.c can replace them. The original functions have aliases with a '__' prefix in their name, so we can call the non-instrumented variant if needed. We must use __memcpy()/__memset() in place of memcpy()/memset() when we copy .data to RAM and when we clear .bss, because kasan_early_init cannot be called before the initialization of .data and .bss. For the kernel compression and EFI libstub's custom string libraries we need a special quirk: even if these are built without KASan enabled, they rely on the global headers for their custom string libraries, which means that e.g. memcpy() will be defined to __memcpy() and we get link failures. Since these implementations are written i C rather than assembly we use e.g. __alias(memcpy) to redirected any users back to the local implementation. Cc: Andrey Ryabinin Cc: Alexander Potapenko Cc: Dmitry Vyukov Cc: kasan-dev@googlegroups.com Reviewed-by: Ard Biesheuvel Tested-by: Ard Biesheuvel # QEMU/KVM/mach-virt/LPAE/8G Tested-by: Florian Fainelli # Brahma SoCs Tested-by: Ahmad Fatoum # i.MX6Q Reported-by: Russell King - ARM Linux Signed-off-by: Ahmad Fatoum Signed-off-by: Abbott Liu Signed-off-by: Florian Fainelli Signed-off-by: Linus Walleij Signed-off-by: Russell King --- arch/arm/lib/memcpy.S | 3 +++ arch/arm/lib/memmove.S | 5 ++++- arch/arm/lib/memset.S | 3 +++ 3 files changed, 10 insertions(+), 1 deletion(-) (limited to 'arch/arm/lib') diff --git a/arch/arm/lib/memcpy.S b/arch/arm/lib/memcpy.S index 09a333153dc6..ad4625d16e11 100644 --- a/arch/arm/lib/memcpy.S +++ b/arch/arm/lib/memcpy.S @@ -58,6 +58,8 @@ /* Prototype: void *memcpy(void *dest, const void *src, size_t n); */ +.weak memcpy +ENTRY(__memcpy) ENTRY(mmiocpy) ENTRY(memcpy) @@ -65,3 +67,4 @@ ENTRY(memcpy) ENDPROC(memcpy) ENDPROC(mmiocpy) +ENDPROC(__memcpy) diff --git a/arch/arm/lib/memmove.S b/arch/arm/lib/memmove.S index b50e5770fb44..fd123ea5a5a4 100644 --- a/arch/arm/lib/memmove.S +++ b/arch/arm/lib/memmove.S @@ -24,12 +24,14 @@ * occurring in the opposite direction. */ +.weak memmove +ENTRY(__memmove) ENTRY(memmove) UNWIND( .fnstart ) subs ip, r0, r1 cmphi r2, ip - bls memcpy + bls __memcpy stmfd sp!, {r0, r4, lr} UNWIND( .fnend ) @@ -222,3 +224,4 @@ ENTRY(memmove) 18: backward_copy_shift push=24 pull=8 ENDPROC(memmove) +ENDPROC(__memmove) diff --git a/arch/arm/lib/memset.S b/arch/arm/lib/memset.S index 6ca4535c47fb..0e7ff0423f50 100644 --- a/arch/arm/lib/memset.S +++ b/arch/arm/lib/memset.S @@ -13,6 +13,8 @@ .text .align 5 +.weak memset +ENTRY(__memset) ENTRY(mmioset) ENTRY(memset) UNWIND( .fnstart ) @@ -132,6 +134,7 @@ UNWIND( .fnstart ) UNWIND( .fnend ) ENDPROC(memset) ENDPROC(mmioset) +ENDPROC(__memset) ENTRY(__memset32) UNWIND( .fnstart ) -- cgit v1.2.3