Dangerous use of ‘cin’¶
ID: cpp/dangerous-cin Kind: problem Security severity: 10.0 Severity: error Precision: high Tags: - reliability - security - external/cwe/cwe-676 Query suites: - cpp-code-scanning.qls - cpp-security-extended.qls - cpp-security-and-quality.qls Click to see the query in the CodeQL repository
This rule finds calls to std::istream::operator>> on std::cin without a preceding call to cin.width. Consuming input from cin without specifying the length of the input is dangerous due to the possibility of buffer overflows.
Recommendation¶
Always specify the length of any input expected from cin by calling cin.width before consuming the input.
Example¶
The following example shows both a dangerous and a safe way to consume input from cin.
#define BUFFER_SIZE 20voidbad(){charbuffer[BUFFER_SIZE];// BAD: Use of 'cin' without specifying the length of the input.cin>>buffer;buffer[BUFFER_SIZE-1]='\0';}voidgood(){charbuffer[BUFFER_SIZE];// GOOD: Specifying the length of the input before using 'cin'.cin.width(BUFFER_SIZE);cin>>buffer;buffer[BUFFER_SIZE-1]='\0';}References¶
Common Weakness Enumeration: CWE-676.
