[LKP] Re: [LTP] [x86/entry] 2bbc68f837: ltp.ptrace08.fail

> do_debug is a bit of a red herring here. ptrace should not be able to > put a breakpoint on a kernel address, period. I would just pick a > fixed address that's in the kernel text range or even just in the > pre-KASLR text range and make sure it gets rejected. Maybe try a few > different addresses for good measure. I've looked at the code and it seems like this would be a bit more complicated since the breakpoint is set by an accident in a race and the call still fails. Which is why the test triggers the breakpoint and causes infinite loop in the kernel... I guess that we could instead read back the address with PTRACE_PEEKUSER, so something as: break_addr = ptrace(PTRACE_PEEKUSER, child_pid, (void *)offsetof(struct user, u_debugreg[0]), NULL); if (break_addr == kernel_addr) tst_res(TFAIL, "ptrace() set break on a kernel address");