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int buf[INTBUFSIZE];
int *buf_ptr = buf;

while (havedata() && buf_ptr < &buf[INTBUFSIZE]) {
  *buf_ptr++ = parseint(getdata());
}

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Noncompliant Code Example

The following This noncompliant code example is based on a flaw in the OpenBSD operating system. An integer, skip, is added as an offset to a pointer of type struct big. The adjusted pointer is then used as a destination address in a call to memset(). However, when skip is added to the struct big pointer, it is automatically scaled by the size of struct big, which is 32 bytes (assuming 4-byte integers, 8-byte long long integers, and no structure padding). This scaling results in the call to memset() writing to unintended memory.

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Failure to understand and properly use pointer arithmetic can allow an attacker to execute arbitrary code.

Automated Detection

How long is 4 yards plus 3 feet? It is obvious from elementary arithmetic that any answer involving 7 is wrong, as the student did not take the units into account. The right method is to convert both numbers to reflect the same units.

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Related Vulnerabilities

Search for vulnerabilities resulting from the violation of this rule on the CERT website.

Related Guidelines

Bibliography

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