malloc.c:3096: sYSMALLOc: Assertion Error using pointers

Question

I'm getting

     malloc.c:3096: sYSMALLOc: Assertion `(old_top == (((mbinptr) (((char *) &((av)->bins[((1) - 1)                        * 2])) - __builtin_offsetof (struct malloc_chunk, fd)))) && old_size == 0) || ((unsigned long) (   old_size) >= (unsigned long)((((__builtin_offsetof (struct malloc_chunk, fd_nextsize))+((2 * (sizeof(size_t))) - 1)) & ~((2 * (sizeof(size_t))) - 1))) && ((old_top)->size & 0x1) && ((unsigned long)old_end & pagemask) == 0)' failed.
     Aborted

Error, I ran valgrind and received

    ==8595==
    ==8595== HEAP SUMMARY:
    ==8595==     in use at exit: 0 bytes in 0 blocks
    ==8595==   total heap usage: 49 allocs, 49 frees, 7,204 bytes allocated
    ==8595==
    ==8595== All heap blocks were freed -- no leaks are possible
    ==8595==
    ==8595== For counts of detected and suppressed errors, rerun with: -v
    ==8595== ERROR SUMMARY: 0 errors from 0 contexts (suppressed: 25 from 6)

which left me confused. The code I believe is causing the problem is:

    int asn1_encoder(char *bufff[]){

    char av[20];


    char boibuff[] = {0x01, 0x00, 0x00, 0x01};

    char propbuff[] = {0x01};
     \\BACnetConfirmedServiceChoice and BACnetConfirmedServiceRequest types have been ommitted
    long int arb = 0;
    long int arb1 = 0;
    BACnet_Confirmed_Request_PDU_t *bacnetConfirmedPDU;
    int i = 0;
    BACnet_Confirmed_Service_Request_t *service_request;
    BACnetConfirmedServiceChoice_t *service_choice;
    WriteProperty_Request_t *writeProperty;
    BACnetObjectIdentifier_t *objectIdentifier;
    BACnetPropertyIdentifier_t *propertyIdentifier;
    asn_enc_rval_t ec;

    sprintf(av,"test.bin");





      bacnetConfirmedPDU = calloc(1, sizeof(BACnet_Confirmed_Request_PDU_t)); //PDU-TYPE deff

      bacnetConfirmedPDU -> service_request  = calloc(1,             sizeof(BACnet_Confirmed_Service_Request_t));

            objectIdentifier = calloc(1, sizeof(BACnetObjectIdentifier_t));
      service_choice = calloc(1, sizeof(BACnetConfirmedServiceChoice_t)); //Select Service deff

      writeProperty = calloc(1, sizeof(WriteProperty_Request_t)); //Encoded service deff

       bacnetConfirmedPDU -> service_request -> choice.writeProperty.objectIdentifier.buf = calloc(1, sizeof(BACnetObjectIdentifier_t));

      propertyIdentifier = calloc(1, sizeof(BACnetPropertyIdentifier_t));


            if(!bacnetConfirmedPDU){
                    perror("calloc() failed");
                    exit(1);
            }

            bacnetConfirmedPDU -> pdu_type = 1;

            bacnetConfirmedPDU -> service_choice  = BACnetConfirmedServiceChoice_writeProperty;
            printf("the value in service_choice struct is %d\n", bacnetConfirmedPDU->service_choice);


            bacnetConfirmedPDU -> service_request -> present = BACnet_Confirmed_Service_Request_PR_writeProperty;
            bacnetConfirmedPDU -> service_request -> choice.writeProperty.objectIdentifier.buf = boibuff; // BACnetObjectType_binary_output;  //boibuff;


            bacnetConfirmedPDU -> service_request -> choice.writeProperty.objectIdentifier.size = 4;
            printf("boi is %02x\n",bacnetConfirmedPDU -> service_request ->choice.writeProperty.objectIdentifier.buf[1]);

            bacnetConfirmedPDU -> service_request -> choice.writeProperty.propertyIdentifier = BACnetPropertyIdentifier_present_value;

            printf("property ident = %d\n", bacnetConfirmedPDU -> service_request -> choice.writeProperty.propertyIdentifier);
            //bacnetConfirmedPDU -> service_request -> choice.writeProperty.propertyArrayIndex = arb1;
            //printf("the value in proper array is %lu\n",bacnetConfirmedPDU -> service_request -> choice.writeProperty.propertyArrayIndex);
            printf("sef fault before propbuff\n");
            bacnetConfirmedPDU -> service_request -> choice.writeProperty.propertyValue.buf =  propbuff;

            bacnetConfirmedPDU -> service_request -> choice.writeProperty.propertyValue.size = sizeof(propbuff);



            //define port


            FILE *fp = fopen(av, "wb+");
            if(fp == NULL){
            printf("fp is null\n");
            }

            if(!fp){
            perror(av);
            exit(1);
            }

            ec = der_encode(&asn_DEF_BACnet_Confirmed_Request_PDU, bacnetConfirmedPDU, write_out, fp);

            if(fp == NULL)
            {
            printf("fp null\n");
            }

             if(!fp){
            perror(av);
            exit(1);
            }

            ec = der_encode(&asn_DEF_BACnet_Confirmed_Request_PDU, bacnetConfirmedPDU, write_out, fp);

            if(fp == NULL)
            {
            printf("fp null\n");

            }

            printf("the file is closed\n");
            int end = fseek(fp, 0, SEEK_END);
            end = ftell(fp);
            fseek(fp, 0, SEEK_SET);
            printf("fseek is happening\n");
            //int end = ftell(fp);
             if(fp == NULL)
            {
            printf("*******************bufff is null***************************\n");
            }

            printf("end equals %d\n", end);
            //printf("just before fgetc\n");
            //for(i = 0; i<= 35 ; i++)
         for(i = 0; i <  end; i++)
         {

            if(feof(fp)){
            printf("we're a broken family\n");
            break;
            }
            if(i> maxlen){
            printf(" buff is full\n");
            break;
            }
             }

            }

            fclose(fp);
            if(ec.encoded == -1){
                    fprintf(stderr, "could not encode ConfirmedRequest_PDU at (%s)\n",
                    ec.failed_type ? ec.failed_type -> name : "unknown");
                            exit(1);
            }else{
                    fprintf(stderr, "Created %s with BER encoded ConfirmedRequestPDU\n", av);
                    }

            xer_fprint(stdout, &asn_DEF_BACnet_Confirmed_Request_PDU, bacnetConfirmedPDU);

            free(bacnetConfirmedPDU);
            free(bacnetConfirmedPDU -> service_request);
            return i;
            }

I cant identify where the issue is caused, I have tried freeing all the variables that I calloc-ed. however, all those sturctures are members of bacnetConfirmedPDU, so, by this, shouldn't freeing just bacnetConfirmedPDU be enough? also, the line:

               free((bacnetConfirmedPDU -> service_request);

is a little worry-sum as it could be a double free? My question is, what other options are there for checking for memory leaks and bound violations other than valgrind? also, is there anything glaringly obvious that could cause an assertion error? Any suggestions are greatly appreciated, also, if anyone does have error detection suggestions, an example would also be greatly appreciated. Thanks

Answer 1

In your code:

 free(bacnetConfirmedPDU);

 free(bacnetConfirmedPDU -> service_request);

You free the pointer of the struct first, then free the member variable, if the memory of that struct bacnetConfirmedPDU is already recollected by the system, that means the vaule of bacnetConfirmedPDU -> service_request might be changed, this could be the problem. So you should:

free(bacnetConfirmedPDU -> service_request);   
free(bacnetConfirmedPDU);