SEI CERT C Coding Standard

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The {{calloc()}} function takes two arguments: the number of elements to allocate and the storage size of those elements. Typically, {{calloc()}} function implementations multiply these arguments together to determine how much memory to allocate. Historically, some implementations failed to check if this multiplication could result in an integer overflow \[[RUS-CERT Advisory 2002-08:02|http://cert.uni-stuttgart.de/advisories/calloc.php]\]. If the result of multiplying the number of elements to allocate and the storage size cannot be represented as a {{size_t}}, less memory is allocated than was requested. As a result, it is necessary to ensure that these arguments, when multiplied, do not result in an integer overflow.

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Code Block
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long *buffer;
size_t num_elements = calc_size();
errno = 0;
(void) multsize_t(num_elements, sizeof(long));
if (errno) {
  /* handle error condition */
}
buffer = calloc(num_elements, sizeof(long));
if (buffer == NULL) {
  /* handle error condition */
}

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