diff options
| author |   Oleg Nesterov <oleg@tv-sign.ru> | 2008-02-04 22:27:24 -0800 |
|---|---|---|
| committer |   Linus Torvalds <torvalds@woody.linux-foundation.org> | 2008-02-05 09:44:07 -0800 |
| commit | ed5d2cac114202fe2978a9cbcab8f5032796d538 (patch) | |
| tree | aa9aaea1aa0945bd9159685d1b04897d105a90c9 /kernel | |
| parent | remove handle_group_stop() in favor of do_signal_stop() (diff) | |
| download | linux-dev-ed5d2cac114202fe2978a9cbcab8f5032796d538.tar.xz linux-dev-ed5d2cac114202fe2978a9cbcab8f5032796d538.zip | |
exec: rework the group exit and fix the race with kill
As Roland pointed out, we have the very old problem with exec. de_thread()
sets SIGNAL_GROUP_EXIT, kills other threads, changes ->group_leader and then
clears signal->flags. All signals (even fatal ones) sent in this window
(which is not too small) will be lost.
With this patch exec doesn't abuse SIGNAL_GROUP_EXIT. signal_group_exit(),
the new helper, should be used to detect exit_group() or exec() in progress.
It can have more users, but this patch does only strictly necessary changes.
Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
Cc: Davide Libenzi <davidel@xmailserver.org>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Robin Holt <holt@sgi.com>
Cc: Roland McGrath <roland@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'kernel')
| -rw-r--r-- | kernel/exit.c | 3 | ||||
| -rw-r--r-- | kernel/signal.c | 4 |
2 files changed, 4 insertions, 3 deletions
diff --git a/kernel/exit.c b/kernel/exit.c index 9e459fefda77..9d3d0f0b27d9 100644 --- a/kernel/exit.c +++ b/kernel/exit.c @@ -1083,11 +1083,12 @@ do_group_exit(int exit_code) struct signal_struct *const sig = current->signal; struct sighand_struct *const sighand = current->sighand; spin_lock_irq(&sighand->siglock); - if (sig->flags & SIGNAL_GROUP_EXIT) + if (signal_group_exit(sig)) /* Another thread got here before we took the lock. */ exit_code = sig->group_exit_code; else { sig->group_exit_code = exit_code; + sig->flags = SIGNAL_GROUP_EXIT; zap_other_threads(current); } spin_unlock_irq(&sighand->siglock); diff --git a/kernel/signal.c b/kernel/signal.c index 1117b28488c2..6a5f97cd337a 100644 --- a/kernel/signal.c +++ b/kernel/signal.c @@ -957,7 +957,6 @@ void zap_other_threads(struct task_struct *p) { struct task_struct *t; - p->signal->flags = SIGNAL_GROUP_EXIT; p->signal->group_stop_count = 0; for (t = next_thread(p); t != p; t = next_thread(t)) { @@ -1697,7 +1696,8 @@ static int do_signal_stop(int signr) } else { struct task_struct *t; - if (!likely(sig->flags & SIGNAL_STOP_DEQUEUED)) + if (!likely(sig->flags & SIGNAL_STOP_DEQUEUED) || + unlikely(sig->group_exit_task)) return 0; /* * There is no group stop already in progress. |