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.NET Forum / .NET Framework / CLR / January 2006Runtime way of catching stack imbalance (ala PInvokeStackImbalance
Hi Our end users need to be able to define native function calls (dll, entry-point, calling conventions, parameters etc.) and these functions are then called at runtime. In debug mode the MDA steps and a displays the PInvokeStackImbalance dialog, but at runtime the function call just fails - no exceptions are raised to be caught. The question is how could I notify the users that their function declaration is wrong? | Hi | Our end users need to be able to define native function calls (dll, [quoted text clipped - 5 lines] | The question is how could I notify the users that their function declaration | is wrong? How to enable MDA's: http://msdn2.microsoft.com/en-us/library/d21c150d(en-US,VS.80).aspx Willy. Hi Willy, Yes, I have tried to use registry and configuration file in this link. However, I still did not managed to get it work, so I will spend some more time on it. Thanks Best regards, Jeffrey Tan Microsoft Online Partner Support  SignatureGet Secure! - www.microsoft.com/security This posting is provided "as is" with no warranties and confers no rights. | Hi Willy, | [quoted text clipped - 7 lines] | Get Secure! - www.microsoft.com/security | This posting is provided "as is" with no warranties and confers no rights. Try to set the environment variable COMPLUS_MDA to 1, this forces the CLR to search the mda config file. set COMPLUS_MDA=1 config file name must look like: application.exe.mda.config Willy. Hi Willy Thanks (again). The problem is not enabling the MDA - I already have it enabled and it works fine in a debug build. The problem is in a release build where the MethodInfo Invoke method does not nothing - no nice exception to catch. It literally does nothing. I need to be able to do something like check the stack status before and after and see whether something has become corrupted or get the Invoke method to raise a meaningful exception. Thanks for you interest in this. Marek > | Hi > | Our end users need to be able to define native function calls (dll, [quoted text clipped - 12 lines] > > Willy. Hi Marek, Thanks for your feedback. I have tried to a configuration file and environment variable to enable MDA in CLR for both debug build and release build. When the p/invoke call stack is not balance, I can get the MDA PInvokeStackImbalance, which causes a JIT debugger to be selected. Do you get the same behavior as me? Also, I have got confirmation from our product team that although we can enable MDA at runtime, it is not shown out as exception, try...catch will have no effect on this. It is something like Assert, not exception. So if you just want a JIT to popup, yes, you can enable MDA at runtime. However, there is no way to catch it as an exception. Hope this helps Best regards, Jeffrey Tan Microsoft Online Partner Support SignatureGet Secure! - www.microsoft.com/security This posting is provided "as is" with no warranties and confers no rights. Hi Jeffrey Thanks very much for looking into this for me. I can't really let my end users be confronted with with a JIT window. Is there anything that could be done in code to test the state of the stack before and after the invoke call which would provide me with any information that I could use to determine whether a stack imbalance had occurred? Thanks again, Marek > Hi Marek, > [quoted text clipped - 18 lines] > Get Secure! - www.microsoft.com/security > This posting is provided "as is" with no warranties and confers no rights. Hi Marek, Thanks for your feedback. Yes, I have already consulted our product team for this issue. However, they confirmed that MDA can not help in this scenario. If you are curious, below is the reply email content: "The StackImbalance MDA also isn’t a catch-all. If you’ve got an application model where the user can cause the CLR to invoke arbitrary native functions calls, then it’s ALWAYS going to be unsafe and have the potential to cause corruption. Invoking native methods is inherently unsafe. The application could use various heuristics to try and weed out some obvious errors, but the CLR doesn’t have any direct support to help them with that." Thanks Best regards, Jeffrey Tan Microsoft Online Partner Support SignatureGet Secure! - www.microsoft.com/security This posting is provided "as is" with no warranties and confers no rights. Hi Jeffrey Thank you again. Please could you point me in the right direction of these "various heuristics". Best regards, Marek > Hi Marek, > [quoted text clipped - 18 lines] > Get Secure! - www.microsoft.com/security > This posting is provided "as is" with no warranties and confers no rights. Hi Marek, If you are curious, below is the feedback from our product team: "In theory an app could do something like PInvoke to their own native wrapper function which would do the work of calling the user-specified native method and trying to detect some forms of corruption that can result from an incorrect call (specifically looking for stack imbalance). Doing this however would be non-trivial and would require a good understanding of the native calling convention etc. Regardless, there are many other ways an incorrect native call could corrupt memory which would be difficult or impossible to detect, and so anything the application were to do here would only provide partial protection (and perhaps a false sense of security). For that reason, I don't think we should be encouraging the customer taking this approach" Hope this helps Best regards, Jeffrey Tan Microsoft Online Partner Support SignatureGet Secure! - www.microsoft.com/security This posting is provided "as is" with no warranties and confers no rights. Hi mav, Thanks for your post. Yes, I can reproduce out this behavior. I will spend some more time in this issue. Thanks Best regards, Jeffrey Tan Microsoft Online Partner Support SignatureGet Secure! - www.microsoft.com/security This posting is provided "as is" with no warranties and confers no rights.
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