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IAR Embedded Workbench for RISC-V 3.40

MEM-use-free-all

In this section:
Synopsis

A pointer is used after it has been freed.

Enabled by default

Yes

Severity/Certainty

High/High

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Full description

Memory is being accessed after it has been deallocated. The application might appear to run normally, but the operation is illegal. The most likely result is a crash, but the application might keep running with erroneous or corrupt data. This check is identical to MISRAC2012-Dir-4.13_d, MISRAC2012-Rule-1.3_o, SEC-BUFFER-use-after-free-all, CERT-MEM30-C_a.

Coding standards
CERT MEM30-C

Do not access freed memory

CWE 416

Use After Free

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);
  *x++;  //x is dereferenced after it is freed
}

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++;  //OK - x is reallocated
}