On Tue, Sep 28, 2021 at 5:42 PM Arnd Bergmann [off-list ref] wrote:

From: Arnd Bergmann <arnd@arndb.de>

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.

Fixes: d6d51a96c7d6 ("ARM: 9014/2: Replace string mem* functions for KASan")
Fixes: a7f464f3db93 ("ARM: 7001/2: Wire up support for the XZ decompressor")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>

Solves this, right?
https://lore.kernel.org/lkml/202105091112.F5rmd4By-lkp@intel.com/ (local)

Can you put in a reported-by and Link: to this so we got it tracked?

 #ifdef CONFIG_KERNEL_XZ
+#undef memmove
 #define memmove memmove
+#undef memcpy
 #define memcpy memcpy
 #include "../../../../lib/decompress_unxz.c"
 #endif

That's clever, maybe drop a small comment in the code why we do this
pretty unintuitive looking thing and how this works?

Reviewed-by: Linus Walleij <redacted>

Yours,
Linus Walleij

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