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SubjectRe: [PATCH v3] x86/boot: Warn on future overlapping memcpy() use
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Argh. I'm hating this patch. :)

Will fix with v4.

On Thu, Apr 28, 2016 at 4:56 PM, kbuild test robot <lkp@intel.com> wrote:
> Hi,
>
> [auto build test ERROR on tip/auto-latest]
> [cannot apply to tip/x86/core v4.6-rc5 next-20160428]
> [if your patch is applied to the wrong git tree, please drop us a note to help improving the system]
>
> url: https://github.com/0day-ci/linux/commits/Kees-Cook/x86-boot-Warn-on-future-overlapping-memcpy-use/20160429-075026
> config: i386-tinyconfig (attached as .config)
> reproduce:
> # save the attached .config to linux build tree
> make ARCH=i386
>
> All error/warnings (new ones prefixed by >>):
>
> arch/x86/boot/compressed/string.c: In function 'memmove':
>>> arch/x86/boot/compressed/string.c:56:10: warning: implicit declaration of function 'memcpy' [-Wimplicit-function-declaration]
> return memcpy(dest, src, n);
> ^
>>> arch/x86/boot/compressed/string.c:56:10: warning: return makes pointer from integer without a cast [-Wint-conversion]
> arch/x86/boot/compressed/string.c: At top level:
>>> arch/x86/boot/compressed/string.c:65:7: error: conflicting types for 'memcpy'
> void *memcpy(void *dest, const void *src, size_t n)
> ^
> arch/x86/boot/compressed/string.c:56:10: note: previous implicit declaration of 'memcpy' was here
> return memcpy(dest, src, n);
> ^
> arch/x86/boot/compressed/string.c: In function 'memcpy':
>>> arch/x86/boot/compressed/string.c:68:3: warning: implicit declaration of function 'warn' [-Wimplicit-function-declaration]
> warn("Avoiding potentially unsafe overlapping memcpy()!");
> ^
>
> vim +/memcpy +65 arch/x86/boot/compressed/string.c
>
> 50 void *memmove(void *dest, const void *src, size_t n)
> 51 {
> 52 unsigned char *d = dest;
> 53 const unsigned char *s = src;
> 54
> 55 if (d <= s || d - s >= n)
> > 56 return memcpy(dest, src, n);
> 57
> 58 while (n-- > 0)
> 59 d[n] = s[n];
> 60
> 61 return dest;
> 62 }
> 63
> 64 /* Detect and warn about potential overlaps, but handle them with memmove. */
> > 65 void *memcpy(void *dest, const void *src, size_t n)
> 66 {
> 67 if (dest > src && dest - src < n) {
> > 68 warn("Avoiding potentially unsafe overlapping memcpy()!");
> 69 return memmove(dest, src, n);
> 70 }
> 71 return __memcpy(dest, src, n);
>
> ---
> 0-DAY kernel test infrastructure Open Source Technology Center
> https://lists.01.org/pipermail/kbuild-all Intel Corporation



--
Kees Cook
Chrome OS & Brillo Security

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