Messages in this thread |  | | Date | Sun, 9 May 2021 17:25:01 +0100 | From | Russell King - ARM Linux admin <> | Subject | Re: arch/arm/boot/compressed/decompress.c:50: warning: "memmove" redefined |
| |
On Sun, May 09, 2021 at 05:17:49PM +0200, Linus Walleij wrote: > OK, paging in the KSan mailing list and key people. > > Certainly this problem must be the same on all platforms > using an XZ-compressed kernel and not just Arm? > > What I wonder is why the other platforms that use > XZ compression don't redefine memmove and > memcpy in their decompress.c clause for XZ? > > Can we just delete these two lines? > #define memmove memmove > #define memcpy memcpy
We can't. XZ has:
#ifndef memmove /* Not static to avoid a conflict with the prototype in the Linux * headers. */ void *memmove(void *dest, const void *src, size_t size) { ... } #endif
So, if memmove is not defined in the preprocessor, the code will create its own implementation. memmove() is also defined in arch/arm/boot/compressed/string.c for use with other decompressors, so the local version in lib/decompress_unxz.c will conflict and cause a link time error.
The addition of KASan added this to arch/arm/include/asm/string.h:
#if defined(CONFIG_KASAN) && !defined(__SANITIZE_ADDRESS__) #define memcpy(dst, src, len) __memcpy(dst, src, len) #define memmove(dst, src, len) __memmove(dst, src, len) #define memset(s, c, n) __memset(s, c, n)
#ifndef __NO_FORTIFY #define __NO_FORTIFY /* FORTIFY_SOURCE uses __builtin_memcpy, etc. */ #endif
#endif
created a conditional definition of memmove in the preprocessor, which ultimately caused this problem. lib/decompress_unxz.c wants it defined in the preprocessor _if_ one has a local implementation (we do.)
Given that KASan should be disabled in the decompressor, maybe the conditional added by KASan to asm/string.h is insufficient? The makefile has:
KASAN_SANITIZE := n
So really we should not be playing _any_ KASan games in the decompressor code.
-- RMK's Patch system: https://www.armlinux.org.uk/developer/patches/ FTTP is here! 40Mbps down 10Mbps up. Decent connectivity at last!
|  |