Kees Cook <keescook@xxxxxxxxxxxx> writes: > On Thu, May 05, 2022 at 01:25:57PM -0500, Eric W. Biederman wrote: >> The states TASK_STOPPED and TASK_TRACE are special in they can not >> handle spurious wake-ups. This plus actively depending upon and >> changing the value of tsk->__state causes problems for PREEMPT_RT and >> Peter's freezer rewrite. >> >> There are a lot of details we have to get right to sort out the >> technical challenges and this is my parred back version of the changes >> that contains just those problems I see good solutions to that I believe >> are ready. >> >> A couple of issues have been pointed but I think this parred back set of >> changes is still on the right track. The biggest change in v4 is the >> split of "ptrace: Admit ptrace_stop can generate spuriuos SIGTRAPs" into >> two patches because the dependency I thought exited between two >> different changes did not exist. The rest of the changes are minor >> tweaks to "ptrace: Admit ptrace_stop can generate spuriuos SIGTRAPs"; >> removing an always true branch, and adding an early test to see if the >> ptracer had gone, before TASK_TRAPPING was set. >> >> This set of changes should support Peter's freezer rewrite, and with the >> addition of changing wait_task_inactive(TASK_TRACED) to be >> wait_task_inactive(0) in ptrace_check_attach I don't think there are any >> races or issues to be concerned about from the ptrace side. >> >> More work is needed to support PREEMPT_RT, but these changes get things >> closer. >> >> This set of changes continues to look like it will provide a firm >> foundation for solving the PREEMPT_RT and freezer challenges. > > One of the more sensitive projects to changes around ptrace is rr > (Robert and Kyle added to CC). I ran rr's selftests before/after this > series and saw no changes. My failures remained the same; I assume > they're due to missing CPU features (pkeys) or build configs (bpf), etc: > > 99% tests passed, 19 tests failed out of 2777 > > Total Test time (real) = 773.40 sec > > The following tests FAILED: > 42 - bpf_map (Failed) > 43 - bpf_map-no-syscallbuf (Failed) > 414 - netfilter (Failed) > 415 - netfilter-no-syscallbuf (Failed) > 454 - x86/pkeys (Failed) > 455 - x86/pkeys-no-syscallbuf (Failed) > 1152 - ttyname (Failed) > 1153 - ttyname-no-syscallbuf (Failed) > 1430 - bpf_map-32 (Failed) > 1431 - bpf_map-32-no-syscallbuf (Failed) > 1502 - detach_sigkill-32 (Failed) > 1802 - netfilter-32 (Failed) > 1803 - netfilter-32-no-syscallbuf (Failed) > 1842 - x86/pkeys-32 (Failed) > 1843 - x86/pkeys-32-no-syscallbuf (Failed) > 2316 - crash_in_function-32 (Failed) > 2317 - crash_in_function-32-no-syscallbuf (Failed) > 2540 - ttyname-32 (Failed) > 2541 - ttyname-32-no-syscallbuf (Failed) > > So, I guess: > > Tested-by: Kees Cook <keescook@xxxxxxxxxxxx> > > :) Thank you. I was thinking it would be good to add the rr folks to the discussion. Eric
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