Memory is never released potential leak of memory

Question

Just ran analyze on my app and it threw up this memory error and pointed to the return line in the following code:

int                 mgmtInfoBase[6];
char                *msgBuffer = NULL;
size_t              length;
unsigned char       macAddress[6];
struct if_msghdr    *interfaceMsgStruct;
struct sockaddr_dl  *socketStruct;
NSString            *errorFlag = NULL;

mgmtInfoBase[0] = CTL_NET;        // Request network subsystem
mgmtInfoBase[1] = AF_ROUTE;       // Routing table info
mgmtInfoBase[2] = 0;
mgmtInfoBase[3] = AF_LINK;        // Request link layer information
mgmtInfoBase[4] = NET_RT_IFLIST;  // Request all configured interfaces

if ((mgmtInfoBase[5] = if_nametoindex("en0")) == 0)
    errorFlag = @"if_nametoindex failure";
else
{
    if (sysctl(mgmtInfoBase, 6, NULL, &length, NULL, 0) < 0)
        errorFlag = @"sysctl mgmtInfoBase failure";
    else
    {
        if ((msgBuffer = malloc(length)) == NULL)
            errorFlag = @"buffer allocation failure";
        else
        {
            if (sysctl(mgmtInfoBase, 6, msgBuffer, &length, NULL, 0) < 0)
                errorFlag = @"sysctl msgBuffer failure";
        }
    }
}

if (errorFlag != NULL)
{
    NSLog(@"Error: %@", errorFlag);        
    return errorFlag;                  // this line gives the memory leak warning
}

I don't know much C and was hoping someone could tell what's going on here.

Answer 1

You need to free msgBuffer

 if ((msgBuffer = malloc(length)) == NULL)

may be you can do it before just before return

if (errorFlag != NULL)
{
    free (msgBuffer); // Free here
    NSLog(@"Error: %@", errorFlag); 
    return errorFlag;                  // this line gives the memory leak warning
}

Answer 2

You are not free ing buffer msgBuffer allocated in this line:

if ((msgBuffer = malloc(length)) == NULL)