From d49f0b14867f0a6527de4d7a553e4b26150ff297 Mon Sep 17 00:00:00 2001
From: David Howells <dhowells@redhat.com>
Date: Fri, 8 May 2009 13:55:27 +0100
Subject: [PATCH] --- yaml --- r: 146423 b: refs/heads/master c:
 107db7c7dd137aeb7361b8c2606ac936c0be58ff h: refs/heads/master i:   146421:
 d107fcf20faec76fe885b318d7cb513024128a5a   146419:
 0b0b81357537035e82c3dbe2cecaa886f1ecb1d8   146415:
 7c5f48eca7fc423c1194aef4fcfef66d8a3f8f30 v: v3

---
 [refs]               | 2 +-
 trunk/fs/proc/base.c | 6 ++++++
 2 files changed, 7 insertions(+), 1 deletion(-)

diff --git a/[refs] b/[refs]
index 604f2900c14b..b65dc1afe787 100644
--- a/[refs]
+++ b/[refs]
@@ -1,2 +1,2 @@
 ---
-refs/heads/master: 5e751e992f3fb08ba35e1ca8095ec8fbf9eda523
+refs/heads/master: 107db7c7dd137aeb7361b8c2606ac936c0be58ff
diff --git a/trunk/fs/proc/base.c b/trunk/fs/proc/base.c
index fb45615943c2..23342e188a66 100644
--- a/trunk/fs/proc/base.c
+++ b/trunk/fs/proc/base.c
@@ -2128,9 +2128,15 @@ static ssize_t proc_pid_attr_write(struct file * file, const char __user * buf,
 	if (copy_from_user(page, buf, count))
 		goto out_free;
 
+	/* Guard against adverse ptrace interaction */
+	length = mutex_lock_interruptible(&task->cred_guard_mutex);
+	if (length < 0)
+		goto out_free;
+
 	length = security_setprocattr(task,
 				      (char*)file->f_path.dentry->d_name.name,
 				      (void*)page, count);
+	mutex_unlock(&task->cred_guard_mutex);
 out_free:
 	free_page((unsigned long) page);
 out: