LOCRET.ARG
Function returns address of local variable
The LOCRET.ARG checker finds instances in which a function returns the address of a local variable by writing it into memory referenced by its argument.
Vulnerability and risk
Local variables are allocated on the stack, so when a function returns a pointer to the variable, it's returning a stack address. The address will be invalidated after returning from the function, so access will probably cause unexpected application behavior, typically a program crash.
Vulnerable code example
Copy
#include <stdlib.h>
void func_ARG(int **pp, unsigned n)
{
int aux;
if (n == 1) {
*pp = &aux;
} else {
*pp = (int *)malloc(n * sizeof(int));
}
}
Klocwork flags line 7, indicating that function func_ARG returns the address of a local variable through its argument. The address of local variable aux can be assigned to *pp, which can be used when the function returns.
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External guidance
Security training
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