[2.6.20.21 review 16/35] setpgid(child) fails if the child was forked by sub-thread

[Willy Tarreau <w@1wt.eu>]

[-- Attachment #1: 0058-setpgid-child-fails-if-the-child-was-forked-by-sub.patch --]
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commit b07e35f94a7b6a059f889b904529ee907dc0634d in mainline tree

Spotted by Marcin Kowalczyk <qrczak@knm.org.pl>.

sys_setpgid(child) fails if the child was forked by sub-thread.

Fix the "is it our child" check. The previous commit
ee0acf90d320c29916ba8c5c1b2e908d81f5057d was not complete.

(this patch asks for the new same_thread_group() helper, but mainline doesn't
 have it yet).

Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
Acked-by: Roland McGrath <roland@redhat.com>
Tested-by: "Marcin 'Qrczak' Kowalczyk" <qrczak@knm.org.pl>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
---
 kernel/sys.c |    3 +--
 1 files changed, 1 insertions(+), 2 deletions(-)

Index: 2.6/kernel/sys.c
===================================================================
--- 2.6.orig/kernel/sys.c
+++ 2.6/kernel/sys.c
@@ -1358,7 +1358,6 @@ asmlinkage long sys_times(struct tms __u
  * Auch. Had to add the 'did_exec' flag to conform completely to POSIX.
  * LBT 04.03.94
  */
-
 asmlinkage long sys_setpgid(pid_t pid, pid_t pgid)
 {
 	struct task_struct *p;
@@ -1386,7 +1385,7 @@ asmlinkage long sys_setpgid(pid_t pid, p
 	if (!thread_group_leader(p))
 		goto out;
 
-	if (p->real_parent == group_leader) {
+	if (p->real_parent->tgid == group_leader->tgid) {
 		err = -EPERM;
 		if (process_session(p) != process_session(group_leader))
 			goto out;

--