[patch 079/114] copy_process: fix CLONE_PARENT && parent_exec_id interaction

Greg KH
2009-03-14T01:49:23Z

[-- Attachment #1: copy_process-fix-clone_parent-parent_exec_id-interaction.patch --]
[-- Type: text/plain, Size: 1867 bytes --]

2.6.28-stable review patch. If anyone has any objections, please let us know.

------------------

From: Oleg Nesterov <oleg@redhat.com>

commit 2d5516cbb9daf7d0e342a2e3b0fc6f8c39a81205 upstream.

CLONE_PARENT can fool the ->self_exec_id/parent_exec_id logic. If we
re-use the old parent, we must also re-use ->parent_exec_id to make
sure exit_notify() sees the right ->xxx_exec_id's when the CLONE_PARENT'ed
task exits.

Also, move down the "p->parent_exec_id = p->self_exec_id" thing, to place
two different cases together.

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Cc: Roland McGrath <roland@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: David Howells <dhowells@redhat.com>
Cc: Serge E. Hallyn <serge@hallyn.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

---
kernel/fork.c | 11 +++++------
1 file changed, 5 insertions(+), 6 deletions(-)

--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -1176,10 +1176,6 @@ static struct task_struct *copy_process(
#endif
clear_all_latency_tracing(p);

- /* Our parent execution domain becomes current domain
- These must match for thread signalling to apply */
- p->parent_exec_id = p->self_exec_id;
-
/* ok, now we should be set up.. */
p->exit_signal = (clone_flags & CLONE_THREAD) ? -1 : (clone_flags & CSIGNAL);
p->pdeath_signal = 0;
@@ -1217,10 +1213,13 @@ static struct task_struct *copy_process(
set_task_cpu(p, smp_processor_id());

/* CLONE_PARENT re-uses the old parent */
- if (clone_flags & (CLONE_PARENT|CLONE_THREAD))
+ if (clone_flags & (CLONE_PARENT|CLONE_THREAD)) {
p->real_parent = current->real_parent;
- else
+ p->parent_exec_id = current->parent_exec_id;
+ } else {
p->real_parent = current;
+ p->parent_exec_id = current->self_exec_id;
+ }

spin_lock(&current->sighand->siglock);