Question about uprobes

W. Michael Petullo mike at flyn.org
Wed Apr 5 20:40:02 EDT 2017


I am writing some software that monitors a guest VM using virtual-machine
introspection and "hijacks" system calls under certain conditions. For
example, the program might inject an int3/breakpoint into the guest
kernel at the entry point to sys_open. When the breakpoint is hit, the
program might set the guest instruction pointer to the address to which
sys_open would have itself returned and set register RAX to some desired
error-code return value.

The problem I am encountering is that for some reason the process is
triggering a "uprobe ... failed to handle uretprobe" message from the
guest kernel.  I do not yet know enough about uprobes to understand what
might be causing this. Is there something in procedures such as sys_open
which must execute to prevent the error which causes the kernel to print
this message?

-- 
Mike

:wq



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