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| Code Block | ||||
|---|---|---|---|---|
| ||||
#include <limits.h>
#include <stddef.h>
#include <inttypes.h>
extern size_t popcount(uintmax_t);
#define PRECISION(x) popcount(x)
void func(signed long si_a, signed long si_b) {
signed long result;
if ((si_a < 0) || (si_b < 0) ||
(si_b >= PRECISION(ULONG_MAX)) ||
(si_a > (LONG_MAX >> si_b))) {
/* Handle error */
} else {
result = si_a << si_b;
}
/* ... */
}
|
Noncompliant Code Example (Right Shift)
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Although shifting a negative number of bits or shifting a number of bits greater than or equal to the width of the promoted left operand is undefined behavior in C, the risk is generally low because processors frequently reduce the shift amount modulo the width of the type.
Rule | Severity | Likelihood | Remediation Cost | Priority | Level |
|---|---|---|---|---|---|
INT34-C | Low | Unlikely | Medium | P2 | L3 |
Automated Detection
Tool | Version | Checker | Description | ||||||
|---|---|---|---|---|---|---|---|---|---|
| Astrée |
| precision-shift-width | Fully checked | ||||||
| Axivion Bauhaus Suite |
|
| CertC-INT34 | Can detect shifts by a negative or an excessive number of bits and right shifts on negative values. | ||||||||
| CodeSonar |
| LANG.ARITH.BIGSHIFT | Shift amount exceeds bit width | ||||||
| Compass/ROSE |
Can detect violations of this rule. Unsigned operands are detected when checking for INT13-C. Use bitwise operators only on unsigned operands | |||||||||
| Coverity |
| BAD_SHIFT | Implemented | ||||||
| Cppcheck |
| shiftNegative, shiftTooManyBits | Context sensitive analysis | ||||||
| Cppcheck Premium |
| shiftNegative, shiftTooManyBits premium-cert-int34-c | Context sensitive analysis Warns whenever Cppcheck sees a negative shift for a POD expression (The warning for shifting too many bits is written only if Cppcheck has sufficient type information and you use --platform to specify the sizes of the standard types.) | ||||||
| ECLAIR |
| CC2.INT34 | Partially implemented | ||||||
| Helix QAC |
| C0499, C2790, C++2790, C++3003 DF2791, DF2792, DF2793 | |||||||
| Klocwork |
| MISRA.SHIFT.RANGE.2012 | |||||||
| LDRA tool suite |
| 51 S, 403 S, 479 S | Partially implemented | ||||||
| Parasoft C/C++test |
| CERT_C-INT34-a | Avoid incorrect shift operations | ||||||
| Polyspace Bug Finder |
|
|
| Checks for:
|
|
Shift operator on negative value
Overflow from shifting operation
Rule partially covered. | ||
| PVS-Studio |
|
|
|
|
|
|
| V610 |
| RuleChecker |
2791 (D)
2792 (A)
2793 (S)
Warns whenever Cppcheck sees a negative shift for a POD expression
(The warning for shifting too many bits is written only if Cppcheck has sufficient type information and you use
--platform to specify the sizes of the standard types.)
| precision-shift-width-constant | Partially checked | |||||||
| TrustInSoft Analyzer |
| shift | Exhaustively verified (see one compliant and one non-compliant example). |
Related Vulnerabilities
Search for vulnerabilities resulting from the violation of this rule on the CERT website.
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Key here (explains table format and definitions)
Taxonomy | Taxonomy item | Relationship |
|---|---|---|
| CERT C | INT13-C. Use bitwise operators only on unsigned operands | Prior to 2018-01-12: CERT: Unspecified Relationship |
| CERT C | INT35-C. Use correct integer precisions | Prior to 2018-01-12: CERT: Unspecified Relationship |
| CERT C | INT32-C. Ensure that operations on signed integers do not result in overflow | Prior to 2018-01-12: CERT: Unspecified Relationship |
| ISO/IEC TR 24772:2013 | Arithmetic Wrap-Around Error [FIF] | Prior to 2018-01-12: CERT: Unspecified Relationship |
| CWE 2.11 | CWE-682 | 2017-07-07: CERT: Rule subset of CWE |
| CWE 2.11 | CWE-758 | 2017-07-07: CERT: Rule subset of CWE |
CERT-CWE Mapping Notes
Key here for mapping notes
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- Incorrect calculations that do not involve out-of-range bit shifts
Bibliography
| [C99 Rationale 2003] | 6.5.7, "Bitwise Shift Operators" |
| [Dowd 2006] | Chapter 6, "C Language Issues" |
| [Seacord 2013b] | Chapter 5, "Integer Security" |
| [Viega 2005] | Section 5.2.7, "Integer Overflow" |
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