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Subject[PATCH] fork.c: fix NULL pointer dereference when nr_threads == threads-max
Date
From: Li Zefan <lizf@cn.fujitsu.com>

I happened to forked lots of processes, and hit NULL pointer dereference.
It is because in copy_process() after checking max_threads, 0 is returned
but not -EAGAIN.

The bug is introduced by this patch:

| commit f1752eec6145c97163dbce62d17cf5d928e28a27
| Author: David Howells <dhowells@redhat.com>
| Date: Fri Nov 14 10:39:17 2008 +1100
|
| CRED: Detach the credentials from task_struct

Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
Signed-off-by: David Howells <dhowells@redhat.com>
---

kernel/fork.c | 1 +
1 files changed, 1 insertions(+), 0 deletions(-)


diff --git a/kernel/fork.c b/kernel/fork.c
index bf0cef8..586874d 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -1007,6 +1007,7 @@ static struct task_struct *copy_process(unsigned long clone_flags,
* triggers too late. This doesn't hurt, the check is only there
* to stop root fork bombs.
*/
+ retval = -EAGAIN;
if (nr_threads >= max_threads)
goto bad_fork_cleanup_count;



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