3.2-stable review patch. If anyone has any objections, please let me know.
------------------ From: Oleg Nesterov <[email protected]> commit e636825346b36a07ccfc8e30946d52855e21f681 upstream. exit_notify() checks "tsk->self_exec_id != tsk->parent_exec_id" to handle the "we have changed execution domain" case. We can change do_thread() to always set ->exit_signal = SIGCHLD and remove this check to simplify the code. We could change setup_new_exec() instead, this looks more logical because it increments ->self_exec_id. But note that de_thread() already resets ->exit_signal if it changes the leader, let's keep both changes close to each other. Note that we change ->exit_signal lockless, this changes the rules. Thereafter ->exit_signal is not stable under tasklist but this is fine, the only possible change is OLDSIG -> SIGCHLD. This can race with eligible_child() but the race is harmless. We can race with reparent_leader() which changes our ->exit_signal in parallel, but it does the same change to SIGCHLD. The noticeable user-visible change is that the execing task is not "visible" to do_wait()->eligible_child(__WCLONE) right after exec. To me this looks more logical, and this is consistent with mt case. Signed-off-by: Oleg Nesterov <[email protected]> Signed-off-by: Linus Torvalds <[email protected]> Signed-off-by: Ben Hutchings <[email protected]> --- fs/exec.c | 3 +++ kernel/exit.c | 7 +------ 2 files changed, 4 insertions(+), 6 deletions(-) diff --git a/fs/exec.c b/fs/exec.c index b0695a9..1e94d22 100644 --- a/fs/exec.c +++ b/fs/exec.c @@ -977,6 +977,9 @@ static int de_thread(struct task_struct *tsk) sig->notify_count = 0; no_thread_group: + /* we have changed execution domain */ + tsk->exit_signal = SIGCHLD; + if (current->mm) setmax_mm_hiwater_rss(&sig->maxrss, current->mm); diff --git a/kernel/exit.c b/kernel/exit.c index 752d2c0..51ac4ce 100644 --- a/kernel/exit.c +++ b/kernel/exit.c @@ -827,14 +827,9 @@ static void exit_notify(struct task_struct *tsk, int group_dead) * If the parent exec id doesn't match the exec id we saved * when we started then we know the parent has changed security * domain. - * - * If our self_exec id doesn't match our parent_exec_id then - * we have changed execution domain as these two values started - * the same after a fork. */ if (thread_group_leader(tsk) && tsk->exit_signal != SIGCHLD && - (tsk->parent_exec_id != tsk->real_parent->self_exec_id || - tsk->self_exec_id != tsk->parent_exec_id)) + tsk->parent_exec_id != tsk->real_parent->self_exec_id) tsk->exit_signal = SIGCHLD; if (unlikely(tsk->ptrace)) { -- 1.7.10 -- To unsubscribe from this list: send the line "unsubscribe stable" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
