diff options
author | Oleg Nesterov <oleg@tv-sign.ru> | 2008-02-04 22:27:23 -0800 |
---|---|---|
committer | Linus Torvalds <torvalds@woody.linux-foundation.org> | 2008-02-05 09:44:07 -0800 |
commit | 198466b41d11dd062fb26ee0376080458d7bfcaf (patch) | |
tree | ccf725c9a05e13b983e4480fd218280d5e58b47e /kernel/signal.c | |
parent | bdff746a3915f109bd13730b6847e33e17e91ed3 (diff) | |
download | op-kernel-dev-198466b41d11dd062fb26ee0376080458d7bfcaf.zip op-kernel-dev-198466b41d11dd062fb26ee0376080458d7bfcaf.tar.gz |
__group_complete_signal(): fix coredump with group stop race
When __group_complete_signal() sees sig_kernel_coredump() signal, it starts
the group stop, but sets ->group_exit_task = t in a hope that "t" will
actually dequeue this signal and invoke do_coredump(). However, by the
time "t" enters get_signal_to_deliver() it is possible that the signal was
blocked/ignored or we have another pending !SIG_KERNEL_COREDUMP_MASK signal
which will be dequeued first. This means the task could be stopped but not
killed.
Remove this code from __group_complete_signal(). Note also this patch
removes the bogus signal_wake_up(t, 1). This thread can't be
STOPPED/TRACED, note the corresponding check in wants_signal().
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/signal.c')
-rw-r--r-- | kernel/signal.c | 30 |
1 files changed, 0 insertions, 30 deletions
diff --git a/kernel/signal.c b/kernel/signal.c index 4333b6d..ea90c34 100644 --- a/kernel/signal.c +++ b/kernel/signal.c @@ -911,27 +911,6 @@ __group_complete_signal(int sig, struct task_struct *p) } while_each_thread(p, t); return; } - - /* - * There will be a core dump. We make all threads other - * than the chosen one go into a group stop so that nothing - * happens until it gets scheduled, takes the signal off - * the shared queue, and does the core dump. This is a - * little more complicated than strictly necessary, but it - * keeps the signal state that winds up in the core dump - * unchanged from the death state, e.g. which thread had - * the core-dump signal unblocked. - */ - rm_from_queue(SIG_KERNEL_STOP_MASK, &t->pending); - rm_from_queue(SIG_KERNEL_STOP_MASK, &p->signal->shared_pending); - p->signal->group_stop_count = 0; - p->signal->group_exit_task = t; - p = t; - do { - p->signal->group_stop_count++; - signal_wake_up(t, t == p); - } while_each_thread(p, t); - return; } /* @@ -1762,15 +1741,6 @@ static int handle_group_stop(void) { int stop_count; - if (current->signal->group_exit_task == current) { - /* - * Group stop is so we can do a core dump, - * We are the initiating thread, so get on with it. - */ - current->signal->group_exit_task = NULL; - return 0; - } - if (current->signal->flags & SIGNAL_GROUP_EXIT) /* * Group stop is so another thread can do a core dump, |