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Add ARM optimized versions of safe_address()

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The function safe_address() uses inline assembler to detect
overflow in size/offset calculations, as detecting this in
plain C is a lot more work.
This commit is contained in:
Ard Biesheuvel 2013-02-05 12:14:55 +01:00
parent 72a728872b
commit d0e0a51c4c
1 changed files with 40 additions and 0 deletions
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40
Zend/zend_alloc.c
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@ -2494,6 +2494,46 @@ static inline size_t safe_address(size_t nmemb, size_t size, size_t offset)
return res;
}
#elif defined(__GNUC__) && defined(__arm__)
static inline size_t safe_address(size_t nmemb, size_t size, size_t offset)
{
size_t res;
unsigned long overflow;
__asm__ ("umull %0,%1,%2,%3\n\tadds %0,%4\n\tadc %1,%1"
: "=&r"(res), "=&r"(overflow)
: "r"(nmemb),
"r"(size),
"r"(offset));
if (UNEXPECTED(overflow)) {
zend_error_noreturn(E_ERROR, "Possible integer overflow in memory allocation (%zu * %zu + %zu)", nmemb, size, offset);
return 0;
}
return res;
}
#elif defined(__GNUC__) && defined(__aarch64__)
static inline size_t safe_address(size_t nmemb, size_t size, size_t offset)
{
size_t res;
unsigned long overflow;
__asm__ ("mul %0,%2,%3\n\tumulh %1,%2,%3\n\tadds %0,%0,%4\n\tadc %1,%1,%1"
: "=&r"(res), "=&r"(overflow)
: "r"(nmemb),
"r"(size),
"r"(offset));
if (UNEXPECTED(overflow)) {
zend_error_noreturn(E_ERROR, "Possible integer overflow in memory allocation (%zu * %zu + %zu)", nmemb, size, offset);
return 0;
}
return res;
}
#elif SIZEOF_SIZE_T == 4 && defined(HAVE_ZEND_LONG64)
static inline size_t safe_address(size_t nmemb, size_t size, size_t offset)