The patch titled
__group_complete_signal(): fix coredump with group stop race
has been added to the -mm tree. Its filename is
__group_complete_signal-fix-coredump-with-group-stop-race.patch
*** Remember to use Documentation/SubmitChecklist when testing your code ***
See http://www.zip.com.au/~akpm/linux/patches/stuff/added-to-mm.txt to find
out what to do about this
------------------------------------------------------
Subject: __group_complete_signal(): fix coredump with group stop race
From: Oleg Nesterov <oleg@xxxxxxxxxx>
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@xxxxxxxxxx>
Cc: Davide Libenzi <davidel@xxxxxxxxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: Robin Holt <holt@xxxxxxx>
Cc: Roland McGrath <roland@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
kernel/signal.c | 30 ------------------------------
1 file changed, 30 deletions(-)
diff -puN kernel/signal.c~__group_complete_signal-fix-coredump-with-group-stop-race kernel/signal.c
--- a/kernel/signal.c~__group_complete_signal-fix-coredump-with-group-stop-race
+++ a/kernel/signal.c
@@ -911,27 +911,6 @@ __group_complete_signal(int sig, struct
} 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;
}
/*
@@ -1756,15 +1735,6 @@ 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,
_
Patches currently in -mm which might be from oleg@xxxxxxxxxx are
origin.patch
fix-cloneclone_newpid.patch
__group_complete_signal-fix-coredump-with-group-stop-race.patch
git-x86.patch
use-__set_task_state-for-traced-stopped-tasks.patch
add-task_wakekill.patch
do_wait-remove-one-else-if-branch.patch
proc-implement-proc_single_file_operations.patch
proc-rewrite-do_task_stat-to-correctly-handle-pid-namespaces.patch
proc-seqfile-convert-proc_pid_statm.patch
proc-proper-pidns-handling-for-proc-self.patch
proc-fix-the-threaded-proc-self.patch
kill-pt_attached.patch
kill-my_ptrace_child.patch
ptrace_check_attach-remove-unneeded-signal-=-null-check.patch
ptrace_stop-fix-the-race-with-ptrace-detachattach.patch
wait_task_stopped-simplify-and-fix-races-with-sigcont-sigkill-untrace.patch
do_wait-factor-out-retval-=-0-checks.patch
ptrace_stop-fix-racy-nonstop_code-setting.patch
wait_task_stopped-remove-unneeded-delay_group_leader-check.patch
do_wait-cleanup-delay_group_leader-usage.patch
do_wait-fix-security-checks.patch
do_wait-fix-security-checks-fix.patch
wait_task_continued-zombie-dont-use-task_pid_nr_ns-lockless.patch
wait_task_zombie-remove-exit_state-exit_signal-checks-for-wnowait.patch
sys_setpgid-simplify-pid-ns-interaction.patch
fix-setsid-for-sub-namespace-sbin-init.patch
teach-set_special_pids-to-use-struct-pid.patch
move-daemonized-kernel-threads-into-the-swappers-session.patch
start-the-global-sbin-init-with-00-special-pids.patch
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