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SubjectRe: [PATCH v3] x86/boot: Warn on future overlapping memcpy() use
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
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