Exception in VmmCacheReserve

[fwdevv]

When i'm reading memory in a fast loop i get this error after about 25 reads

Image

my code :

VmmProcInitialize(ctx);
PVMM_CONTEXT ctxVmm = (PVMM_CONTEXT)ctx->hVMM;
PVMM_PROCESS proc = VmmProcessGet(ctxVmm, procId);

while (1) {
    int num;
    VmmRead(ctxVmm, proc, address, &num, sizeof(num));

    printf("%d\n", num);

    Sleep(150);
}

thanks for any help

[ufrisk]

Thanks for reporting this memory corruption issue. I'll try to look into it, but it may take some days or weeks unfortunately (lack of time right now).

[ufrisk]

Can you please try the following code snippet instead to see if it's working better?

I'm not sure it's the problem that is why it would be interesting to see if the problem goes away if you test this. The Vmm* functions aren't really thread safe, and there is an internal updater thread in there doing some periodic upkeeping. The file system functions and the updater thread both competes for the lock inside PCILeech, but you're not doing that. That may (or may not) be the reason for this issue.

VmmProcInitialize(ctx);
PVMM_CONTEXT ctxVmm = (PVMM_CONTEXT)ctx->hVMM;
PVMM_PROCESS proc;

while (1) {
    int num;
    EnterCriticalSection(&ctxVmm->MasterLock);
    proc = VmmProcessGet(ctxVmm, procId);
    VmmRead(ctxVmm, proc, address, &num, sizeof(num));
    LeaveCriticalSection(&ctxVmm->MasterLock);

    printf("%d\n", num);

    Sleep(150);
}

[ufrisk]

I suspect this issue has to do with the lack of synchronization over the VMM functionality - which does not support multi-threaded access by default. If this problem should still be an issue even after the lock is applied - or in the DLL I just made available please re-open the issue.

[fwdevv]

your fix seems to work thank you very much

[ufrisk]

Awesome, thanks for letting me know.

Also you might be interested in the DLL if it better suits your needs.