On Sat, Feb 02, 2019 at 09:49:38PM -1000, Jack Andersen wrote: > The patch titled > `signal: Never allocate siginfo for SIGKILL or SIGSTOP` > created a regression for users of PTRACE_GETSIGINFO needing to > discern signals that were raised via the tgkill syscall. > > A notable user of this tgkill+ptrace combination is lldb while > debugging a multithreaded program. Without the ability to detect a > SIGSTOP originating from tgkill, lldb does not have a way to > synchronize on a per-thread basis and falls back to SIGSTOP-ing the > entire process. > > This patch allocates the siginfo as it did previously whenever the > SI_TKILL code is present. > > Signed-off-by: Jack Andersen <[email protected]>
The commit you're trying to fix has been discussed before wrt to seccomp tests: commit 2bd61abead58c82714a1f6fa6beb0fd0df6a6d13 Author: Kees Cook <[email protected]> Date: Thu Dec 6 15:50:38 2018 -0800 selftests/seccomp: Remove SIGSTOP si_pid check Commit f149b3155744 ("signal: Never allocate siginfo for SIGKILL or SIGSTOP") means that the seccomp selftest cannot check si_pid under SIGSTOP anymore. Since it's believed[1] there are no other userspace things depending on the old behavior, this removes the behavioral check in the selftest, since it's more a "extra" sanity check (which turns out, maybe, not to have been useful to test). [1] https://lkml.kernel.org/r/cagxu5jjazaozp1qfz66tyrtbuywqb+un2soa1vlhpccoiyv...@mail.gmail.com Reported-by: Tycho Andersen <[email protected]> Suggested-by: Eric W. Biederman <[email protected]> Signed-off-by: Kees Cook <[email protected]> Signed-off-by: Shuah Khan <[email protected]> Ccing Kees on this. Seems that this commit might be worth given that there's some parts of userspace relying on it and not just internal kernel tests. Christian
