i used simple test code , created object in java.
i used system.identityhashcode function equivalent address. please see question asked more context: click here
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end now question is, how know above numbers generated caused aslr. using windows 7 , cannot switch aslr off.
in other words if aslr switched off think same number generated each time run code?
sample code used:
// public class hashcodetest { public int hashcode() { return 0xdeadbeef; } public static void main(string[] argv) { hashcodetest o1 = new hashcodetest(); system.out.println("first: " + o1); system.out.println("using system.identityhashcode():"); system.out.println("first: " + system.identityhashcode(o1)); } } edit:
what trying accomplish? want see if address space layout randomization (aslr) more effective in windows 7 in windows vista want plot frequency distribution curve or use other statistical tools on data see if more predictable in 1 os compared other applications in general.
i person suggested op should use identityhashcode() values ersatz memory addresses. idea that, though not real memory addresses, based on memory address of object in question when identityhashcode() first called ... on typical jvm implementation. makes them reasonable proxy real memory addresses, purposes of experiment.
my answer op results suggest aslr either not enabled, or not effective in randomizing actual addresses of java objects.
i expect amount of natural unpredictability in object address because of non-deterministic factors in jvm bootstrap sequence. why seeing 3 or 4 different hashcode values object in different runs. however, fact seeing values repeatedly suggests there no systematic randomization happening. in other words, no aslr.
strictly speaking, should examine jvm source code check identityhashcode reporting would change if aslr effective ... don't have time right now.
(fwiw: agree other people have answered / commented aslr not needed java anyway. modulo unpatched bug in jvm native code, java jvm not allow sandboxed java program inject executable (native) code. , privileged java program via custom native library.)
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