LANG.ARITH.BIGSHIFT : Shift Amount Exceeds Bit Width

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data << shift_amount
/* or */
data >> shift_amount

occurs with shift_amount greater than the size (in bits) of data's type.

If the type of data is smaller than an int, a warning will only be triggered if shift_amount greater than the size (in bits) of int.

If the shift expression is cast implicitly or explicitly to a different type, the check for this class is based on the size of that type (rather than the size of data's type).

Class Name

Shift Amount Exceeds Bit Width

Significance

security

Mnemonic

LANG.ARITH.BIGSHIFT

Categories

MisraC2023	MisraC2023:1.3	There shall be no occurrence of undefined or critical unspecified behaviour
	MisraC2023:12.2	The right hand operand of a shift operator shall lie in the range zero to one less than the width in bits of the essential type of the left hand operand
Misra2012	Misra2012:1.3	There shall be no occurrence of undefined or critical unspecified behaviour
	Misra2012:12.2	The right hand operand of a shift operator shall lie in the range zero to one less than the width in bits of the essential type of the left hand operand
Misra2004	Misra2004:12.8	The right-hand operand of a shift operator shall lie between zero and one less than the width in bits of the underlying type of the left-hand operand
AUTOSARC++14	AUTOSARC++14:M5-8-1	The right hand operand of a shift operator shall lie between zero and one less than the width in bits of the underlying type of the left hand operand.
MisraC++2008	MisraC++2008:5-8-1	The right hand operand of a shift operator shall lie between zero and one less than the width in bits of the underlying type of the left hand operand.
MisraC++2023	MisraC++2023:4.1.3	There shall be no occurrence of undefined or critical unspecified behaviour
	MisraC++2023:7.0.4	The operands of bitwise operators and shift operators shall be appropriate
CWE	CWE:758	Reliance on Undefined, Unspecified, or Implementation-Defined Behavior
	CWE:1335	Incorrect Bitwise Shift of Integer
CERT-C	CERT-C: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
	CERT-C:INT35-C	Use correct integer precisions
JSF++	JSF++:164	The right hand operand of a shift operator shall lie between zero and one less than the width in bits of the left-hand operand (inclusive).

Availability

Available for C and C++.

Enabling

Checks for this warning class are enabled by default. To disable them, add the following WARNING_FILTER rule to the project configuration file.

WARNING_FILTER += discard class="Shift Amount Exceeds Bit Width"

int do_bigshift(void){
    int a = 50;
    int b = a << 200;   /* 'Shift Amount Exceeds Bit Width' warning issued here */
    return a+b;
}

The following configuration file parameters affect checks for this warning class.

LANG.ARITH.BIGSHIFT : Shift Amount Exceeds Bit Width

Summary

Properties

Example

Relevant Configuration File Parameters