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MISRA C:2023 Dir 4.12

Dynamic memory allocation shall not be used

Since R2024a

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Description

Rule Definition

Dynamic memory allocation shall not be used.

Rationale

Using dynamic memory allocation and deallocation routines provided by the Standard Library or third-party libraries can cause undefined behavior. For instance:

  • You use free to deallocate memory that you did not allocate with malloc, calloc, or realloc.

  • You use a pointer that points to a freed memory location.

  • You access allocated memory that has no value stored into it.

Dynamic memory allocation and deallocation routines from third-party libraries are likely to exhibit similar undefined behavior.

If you choose to use dynamic memory allocation and deallocation routines, ensure that your program behavior is predictable. For example, ensure that you safely handle allocation failure due to insufficient memory.

Troubleshooting

If you expect a rule violation but do not see it, refer to Diagnose Why Coding Standard Violations Do Not Appear as Expected.

Examples

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#include <stdlib.h>

static int foo(void);

typedef struct struct_1 {
    int a;
    char c;
} S_1;

static int foo(void) {

    S_1 * ad_1;
    int  * ad_2;
    int  * ad_3;

    ad_1 = (S_1*)calloc(100U, sizeof(S_1));        /* Non-compliant */
    ad_2 = malloc(100U * sizeof(int));             /* Non-compliant */
    ad_3 = realloc(ad_3, 60U * sizeof(long));      /* Non-compliant */

    free(ad_1);                                    /* Non-compliant */
    free(ad_2);                                    /* Non-compliant */
    free(ad_3);                                    /* Non-compliant */

    return 1;
}

In this example, the rule is violated when the functions malloc, calloc, realloc and free are used.

Check Information

Group: Code Design
Category: Required
AGC Category: Required

Version History

Introduced in R2024a

See Also

Topics