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The C Standard, 6.5.7, paragraph 4 [ISO/IEC 9899:2011], states

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In almost every case, an attempt to shift by a negative number of bits or by more bits than exist in the operand indicates a logic error. These issues are covered by INT34-C. Do not shift an expression by a negative number of bits or by greater than or equal to the number of bits that exist in the operand.

Noncompliant Code Example

This noncompliant code example performs a left shift, after verifying that the number being shifted is not negative, and the number of bits to shift is valid.  The PRECISION() macro and popcount() function provide the correct precision for any integer type. (See INT35-C. Use correct integer precisions.) However, because this code does no overflow check, it can result in an unrepresentable value. 

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Compliant Solution

This compliant solution eliminates the possibility of overflow resulting from a left-shift operation:

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STATIC

Tool

Version

Checker

Description

CodeSonar
Include Page
CodeSonar_V
CodeSonar_V

ALLOC.SIZE.ADDOFLOW
ALLOC.SIZE.IOFLOW
ALLOC.SIZE.MULOFLOW
ALLOC.SIZE.SUBUFLOW
MISC.MEM.SIZE.ADDOFLOW
MISC.MEM.SIZE.BAD
MISC.MEM.SIZE.MULOFLOW
MISC.MEM.SIZE.SUBUFLOW

Addition overflow of allocation size
Integer overflow of allocation size
Multiplication overflow of allocation size
Subtraction underflow of allocation size
Addition overflow of size
Unreasonable size argument
Multiplication overflow of size
Subtraction underflow of size

Coverity6.5
Include Page
Coverity_V
Coverity_V

TAINTED_

Fully implemented

SCALAR

BAD_SHIFT

Implemented
LDRA tool suite
Include Page
LDRA_V
LDRA_V

493 S, 494 S

Partially implemented
Polyspace Bug FinderR2016a

Integer overflow, Tainted division operand

Overflow from operation between integers

Division / operands from an unsecure source

PRQA QA-C
Include Page
PRQA QA-C_v
PRQA QA-C_v

2800, 2801, 2802, 2803,2860,2861,2862,2863

Fully implemented

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