Guarded Free¶
ID: cpp/guarded-free
Kind: problem
Security severity:
Severity: recommendation
Precision: very-high
Tags:
- maintainability
- readability
Query suites:
- cpp-security-and-quality.qls
Click to see the query in the CodeQL repository
The free function, which deallocates heap memory, may accept a NULL pointer and take no action. Therefore, it is unnecessary to check the argument for the value of NULL before a function call to free. As such, these guards may hinder performance and readability.
Recommendation¶
A function call to free should not depend upon the value of its argument. Delete the condition preceding a function call to free when its only purpose is to check the value of the pointer to be freed.
Example¶
void test()
{
char *foo = malloc(100);
// BAD
if (foo)
free(foo);
// GOOD
free(foo);
}
In this example, the condition checking the value of foo can be deleted.
References¶
The Open Group Base Specifications Issue 7, 2018 Edition: free - free allocated memory.