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IAR Embedded Workbench for RL78 5.20

CERT-MEM30-C_b

In this section:
Synopsis

Do not access freed memory.

Enabled by default

Yes

Severity/Certainty

High/High

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Full description

Evaluating a pointer-including dereferencing the pointer, using it as an operand of an arithmetic operation, type casting it, and using it as the right-hand side of an assignment-into memory that has been deallocated by a memory management function is undefined behavior. This check is identical to MISRAC2012-Dir-4.13_e, MISRAC2012-Rule-1.3_p, SEC-BUFFER-use-after-free-some, MEM-use-free-some.

Coding standards
CERT MEM30-C

Do not access freed memory

CWE 416

Use After Free

CWE 456

Missing Initialization

CWE 672

Operation on a Resource after Expiration or Release

CWE 758

Reliance on Undefined, Unspecified, or Implementation-Defined Behavior

MISRA C:2012 Dir-4.13

(Advisory) Functions which are designed to provide operations on a resource should be called in an appropriate sequence

MISRA C:2012 Rule-1.3

(Required) There shall be no occurrence of undefined or critical unspecified behaviour

Code examples

The following code example fails the check and will give a warning:

#include <stdlib.h>

void example(void) {
    int *x;
    x = (int *)malloc(sizeof(int));
    free(x);
    if (rand()) {
        x = (int *)malloc(sizeof(int));
    }
    else {
        /* x not reallocated along this path */
    }
    (*x)++;
}

The following code example passes the check and will not give a warning about this issue:

#include <stdlib.h>

void example(void) {
    int *x;
    x = (int *)malloc(sizeof(int));
    free(x);
    x = (int *)malloc(sizeof(int));
    *x++;
}