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MSC17-C-EX2: When control flow is intended to cross statement labels, it is permissible to omit the break statement. In these instances, the unusual control flow must be explicitly documentedmade clear, such as by adding the [[fallthrough]] C2x attribute, the __attribute__((__fallthrough__)) GNU extension, or a simple comment.
| Code Block | ||||
|---|---|---|---|---|
| ||||
enum WidgetEnum { WE_W, WE_X, WE_Y, WE_Z } widget_type;
widget_type = WE_X;
switch (widget_type) {
case WE_W:
/* ... */
/* No break; fall processthrough caseto forthe WE_X ascase well */
case WE_X:
/* ... */
break;
case WE_Y: case WE_Z:
/* ... */
break;
default: /* Can't happen */
/* Handle error condition */
}
|
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Failure to include break statements leads to unexpected control flow.
Recommendation | Severity | Likelihood | Remediation Cost | Priority | Level |
|---|---|---|---|---|---|
MSC17-C | Medium | Likely | Low | P18 | L1 |
Automated Detection
Tool | Version | Checker | Description | ||||||
|---|---|---|---|---|---|---|---|---|---|
| Astrée |
| switch-clause-break switch-clause-break-continue switch-clause-break-return | Fully checked | ||||||
| CodeSonar |
| LANG.STRUCT.SW.MB | Missing break | ||||||
| Compass/ROSE |
| MISSING_BREAK | Can find instances of missing break statement between cases in | |||||||
| CC2.MSC17 | Fully implemented | |||||||
| Helix QAC |
| C2003 | |||||||
| Klocwork |
| MISRA.SWITCH.WELL_FORMED.BREAK.2012 | |||||||
| LDRA tool suite |
| 62 S | Fully implemented | ||||||
| Parasoft C/C++test |
| CERT_C-MSC17-a | Missing break statement between cases in a switch statement | |||||||
| PC-lint Plus |
| 616, 825 | Fully supported | ||||||
| CERT C: Rec. MSC17-C | Checks for missing break of switch case (rec. fully covered) | |||||||
| PVS-Studio |
| V796 | |||||||
| RuleChecker |
| switch-clause-break switch-clause-break-continue switch-clause-break-return | Fully checked |
| SonarQube C/C++ Plugin |
| NonEmptyCaseWithoutBreak |
Related Vulnerabilities
Search for vulnerabilities resulting from the violation of this rule on the CERT website.
Related Guidelines
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