| Message ID | 87v9ne5y4y.fsf_-_@x220.int.ebiederm.org (mailing list archive) |
|---|---|
| Headers | show |
| Series | Infrastructure to allow fixing exec deadlocks | expand |
On 3/8/20 10:34 PM, Eric W. Biederman wrote: > > Bernd, everyone > > This is how I think the infrastructure change should look that makes way > for fixing this issue. > > - Cleanup and reorder the code so code that can potentially wait > indefinitely for userspace comes at the beginning for flush_old_exec. > - Add a new mutex and take it after we have passed any potential > indefinite waits for userspace. > > Then I think it is just going through the existing users of > cred_guard_mutex and fixing them to use the new one. > > There really aren't that many users of cred_guard_mutex so we should be > able to get through the easy ones fairly quickly. And anything that > isn't easy we can wait until we have a good fix. > > The users of cred_guard_mutex that I saw were: > fs/proc/base.c: > proc_pid_attr_write > do_io_accounting > proc_pid_stack > proc_pid_syscall > proc_pid_personality > > perf_event_open > mm_access > kcmp > pidfd_fget > seccomp_set_mode_filter > > Bernd I think I have addressed the issues you pointed out in v1. > Please let me know if you see anything else. > Yes, looks good, except some nits. Thanks Bernd.
Bernd, everyone This is how I think the infrastructure change should look that makes way for fixing this issue. - Cleanup and reorder the code so code that can potentially wait indefinitely for userspace comes at the beginning for flush_old_exec. - Add a new mutex and take it after we have passed any potential indefinite waits for userspace. Then I think it is just going through the existing users of cred_guard_mutex and fixing them to use the new one. There really aren't that many users of cred_guard_mutex so we should be able to get through the easy ones fairly quickly. And anything that isn't easy we can wait until we have a good fix. The users of cred_guard_mutex that I saw were: fs/proc/base.c: proc_pid_attr_write do_io_accounting proc_pid_stack proc_pid_syscall proc_pid_personality perf_event_open mm_access kcmp pidfd_fget seccomp_set_mode_filter Bernd I think I have addressed the issues you pointed out in v1. Please let me know if you see anything else. Eric W. Biederman (5): exec: Only compute current once in flush_old_exec exec: Factor unshare_sighand out of de_thread and call it separately exec: Move cleanup of posix timers on exec out of de_thread exec: Move exec_mmap right after de_thread in flush_old_exec exec: Add a exec_update_mutex to replace cred_guard_mutex fs/exec.c | 65 ++++++++++++++++++++++++++++++-------------- include/linux/sched/signal.h | 9 +++++- init/init_task.c | 1 + kernel/fork.c | 1 + 4 files changed, 54 insertions(+), 22 deletions(-)