Create new application thread and make it start at a specific function

[Mihai Enache]

Hi! I'm trying to create a new application thread from within my client that should start from one of the functions that I identified in the binary. I have the PC of that function and I assign it to a function pointer which I then pass to the clone syscall to initialise the new thread. However, the new thread crashes at the specified PC (Tool internal crash at PC <here is the PC I passed to clone>).

I'm not sure how to debug this further. Am I on the right track or is this the wrong approach? Any advice would be appreciated.

Thank you.

[Derek Bruening]

First, the clone syscall does not take a function pointer argument: that's a separate thing in the libc wrapper.  Second, how is this syscall being invoked?

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[Mihai Enache]

Thanks for your comment Derek and apologies for my delayed reply. When I wrote the question the clone libcwrapper was called from within a clean call, which I believe was wrong. I managed to fix it by inserting the call to clone as an app instruction and now I'm able to create the additional thread as required initially.