github-mirror/linux
1
0
Fork 0
mirror of https://github.com/torvalds/linux.git synced 2026-06-08 14:42:37 +02:00
Code Issues Actions Packages Projects Releases Wiki Activity Graph

ptrace: don't clear GROUP_STOP_SIGMASK on double-stop

Browse Source 
[This does not correspond to any specific patch in the upstream tree as it was
fixed accidentally by rewriting the code in the 3.1 release]

https://bugzilla.redhat.com/show_bug.cgi?id=740121

1. Luke Macken triggered WARN_ON(!(group_stop & GROUP_STOP_SIGMASK))
   in do_signal_stop().

   This is because do_signal_stop() clears GROUP_STOP_SIGMASK part
   unconditionally but doesn't update it if task_is_stopped().

2. Looking at this problem I noticed that WARN_ON_ONCE(!ptrace) is
   not right, a stopped-but-resumed tracee can clone the untraced
   thread in the SIGNAL_STOP_STOPPED group, the new thread can start
   another group-stop.

   Remove this warning, we need more fixes to make it true.

Reported-by: Luke Macken <lmacken@redhat.com>
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
This commit is contained in:
Oleg Nesterov 2011-09-26 19:06:32 +02:00 committed by Greg Kroah-Hartman
parent eb4b2df8f2
commit 43742b14ff
1 changed files with 1 additions and 3 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

4
kernel/signal.c
View File

@ -1894,21 +1894,19 @@ static int do_signal_stop(int signr)
*/
if (!(sig->flags & SIGNAL_STOP_STOPPED))
sig->group_exit_code = signr;
else
WARN_ON_ONCE(!task_ptrace(current));
current->group_stop &= ~GROUP_STOP_SIGMASK;
current->group_stop |= signr | gstop;
sig->group_stop_count = 1;
for (t = next_thread(current); t != current;
t = next_thread(t)) {
t->group_stop &= ~GROUP_STOP_SIGMASK;
/*
* Setting state to TASK_STOPPED for a group
* stop is always done with the siglock held,
* so this check has no races.
*/
if (!(t->flags & PF_EXITING) && !task_is_stopped(t)) {
t->group_stop &= ~GROUP_STOP_SIGMASK;
t->group_stop |= signr | gstop;
sig->group_stop_count++;
signal_wake_up(t, 0);