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mytypedef_t x;

printf("%lu%llu", x);

Compliant Solution (printf())

This compliant solution uses the correct format for the type being usedguarantees that the correct value of x is printed, regardless of its length, provided that mytypedef_t is an unsigned type.

mytypedef_t x;

printf("%ju", (uintmax_t)x);

Non-Compliant Code Example (scanf())

There is no guarantee that this This non-compliant code example prints the correct value of xwill result in a "buffer overflow", if the size of mytypedef_t is smaller than unsigned long long or it may result in an incorrect value if the size of mytypedef_t is larger than unsigned long long.

mytypedef_t x;

scanf("%lu%llu", &x);

Compliant Solution (scanf())

This compliant solution uses the correct format for the type being usedguarantees that a correct value in the range of mytypedef_t is read, or an error condition is detected.

mytypedef_t x;
uintmax_t temp;

scanf("%ju", &temp);
if (temp > MYTYPEDEF_MAX) {
  /* handle error */
}
x = temp;

Risk Assessment

Failure to use an appropriate conversion specifier when inputting or outputting user-defined integer types can result in buffer overflow and lost or misinterpreted data.

Related Vulnerabilities

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

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