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Commit a98fdcef941e107eeabae622d85a1f476f25a160

Authored by Oleg Nesterov
Committed by Linus Torvalds
1 parent 4fd3670eb1
Exists in master and in 7 other branches imx_3.0.35_4.1.0, imx_3.10.17_1.0.1_ga, imx_3.10.53_1.1.0_ga, imx_3.14.28_1.0.0_ga, smarc-imx_3.10.53_1.1.0_ga, smarc-imx_3.14.28_1.0.0_ga, smarc-l5.0.0_1.0.0-ga

fix the "remove task_ppid_nr_ns" commit 

Commit 84427eaef1fb91704c7112bdb598c810003b99f3 (remove task_ppid_nr_ns)
moved the task_tgid_nr_ns(task->real_parent) outside of lock_task_sighand().
This is wrong, ->real_parent could be freed/reused.

Both ->parent/real_parent point to nothing after __exit_signal() because
we remove the child from ->children list, and thus the child can't be
reparented when its parent exits.

rcu_read_lock() protects ->parent/real_parent, but _only_ if we know it was
valid before we take rcu lock.

Revert this part of the patch.

Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Showing 1 changed file with 1 additions and 1 deletions Side-by-side Diff

... ... @@ -426,7 +426,6 @@
426 426 cgtime = gtime = cputime_zero;
427 427  
428 428 rcu_read_lock();
429   - ppid = task_tgid_nr_ns(task->real_parent, ns);
430 429 if (lock_task_sighand(task, &flags)) {
431 430 struct signal_struct *sig = task->signal;
432 431  
... ... @@ -465,6 +464,7 @@
465 464 }
466 465  
467 466 sid = task_session_nr_ns(task, ns);
  467 + ppid = task_tgid_nr_ns(task->real_parent, ns);
468 468 pgid = task_pgrp_nr_ns(task, ns);
469 469  
470 470 unlock_task_sighand(task, &flags);