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Tool | Version | Checker | Description | ||||||
|---|---|---|---|---|---|---|---|---|---|
| 94 S 540 S | Fully implemented | |||||||
| GCC |
| Can detect some violations of this rule when the | |||||||
| EDG | |||||||||
| Compass/ROSE | Can detect violations of this rule. However, it does not flag explicit casts to | ||||||||
| castexpr | Fully implemented |
Noncompliant Code Example
For objects declared on the stack, The C Standard [ISO/IEC 9899:2011] provides alignas to declare an object to have a stricter alignment. This can be used to resolve the following noncompliant code example.
| Code Block |
|---|
char c = 'x';
int *ip = (int *)&c; /* this can lose information */
char *cp = (char *)ip;
assert(cp == &c); /* will fail on some conforming implementations */
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Compliant Solution
The compliant solution uses alignas to align the the character c to the alignment of an integer. As a result, the two pointers point to equally aligned pointer types.
| Code Block |
|---|
alignas(int) char c = 'x'; /* align c to the alignment of an int */
int *ip = (int *)&c;
char *cp = (char *)ip;
assert(cp == &c); /* both cp and &c point to equally aligned objects */
|
Related Vulnerabilities
Search for vulnerabilities resulting from the violation of this rule on the CERT website.
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CERT C++ Secure Coding Standard: EXP36-CPP. Do not convert pointers into more strictly aligned pointer types
ISO/IEC 9899:2011 Section 6.2.5, "Types"
ISO/IEC TR 17961 (Draft) Converting pointer values to more strictly aligned pointer types [alignconv]
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