Hi!

> commit eaf6cc7165c9c5aa3c2f9faa03a98598123d0afb upstream.
> 
> Both the decompressor code and the kasan logic try to override
> the memcpy() and memmove()  definitions, which leading to a clash
> in a KASAN-enabled kernel with XZ decompression:
> 
> arch/arm/boot/compressed/decompress.c:50:9: error: 'memmove' macro redefined [-Werror,-Wmacro-redefined]
>  #define memmove memmove
>         ^
> arch/arm/include/asm/string.h:59:9: note: previous definition is here
>  #define memmove(dst, src, len) __memmove(dst, src, len)
>         ^
> arch/arm/boot/compressed/decompress.c:51:9: error: 'memcpy' macro redefined [-Werror,-Wmacro-redefined]
>  #define memcpy memcpy
>         ^
> arch/arm/include/asm/string.h:58:9: note: previous definition is here
>  #define memcpy(dst, src, len) __memcpy(dst, src, len)
>         ^
> 
> Here we want the set of functions from the decompressor, so undefine
> the other macros before the override.

AFAICT the conflicting defines are not present in v4.4 or v5.10, so
warnings should not be there and #undefs are not needed.

Best regards,
								Pavel

> +++ b/arch/arm/boot/compressed/decompress.c
> @@ -47,7 +47,10 @@ extern char * strchrnul(const char *, in
>  #endif
>  
>  #ifdef CONFIG_KERNEL_XZ
> +/* Prevent KASAN override of string helpers in decompressor */
> +#undef memmove
>  #define memmove memmove
> +#undef memcpy
>  #define memcpy memcpy
>  #include "../../../../lib/decompress_unxz.c"
>  #endif
> 

-- 
http://www.livejournal.com/~pavelmachek