From: Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>
Date: Fri, 4 Feb 2011 18:13:24 +0000 (+0000)
Subject: CRED: Fix kernel panic upon security_file_alloc() failure.
X-Git-Tag: v2.6.32.30~56
X-Git-Url: http://xenbits.xensource.com/gitweb?a=commitdiff_plain;h=1c0cd1eb0fff83be95a3fcec991ba4f1b09ff18b;p=linux-pvops.git

CRED: Fix kernel panic upon security_file_alloc() failure.

commit 78d2978874e4e10e97dfd4fd79db45bdc0748550 upstream.

In get_empty_filp() since 2.6.29, file_free(f) is called with f->f_cred == NULL
when security_file_alloc() returned an error.  As a result, kernel will panic()
due to put_cred(NULL) call within RCU callback.

Fix this bug by assigning f->f_cred before calling security_file_alloc().

Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
---

diff --git a/fs/file_table.c b/fs/file_table.c
index 666c7ce1fc41..464248f25f4b 100644
--- a/fs/file_table.c
+++ b/fs/file_table.c
@@ -121,13 +121,13 @@ struct file *get_empty_filp(void)
 		goto fail;
 
 	percpu_counter_inc(&nr_files);
+	f->f_cred = get_cred(cred);
 	if (security_file_alloc(f))
 		goto fail_sec;
 
 	INIT_LIST_HEAD(&f->f_u.fu_list);
 	atomic_long_set(&f->f_count, 1);
 	rwlock_init(&f->f_owner.lock);
-	f->f_cred = get_cred(cred);
 	spin_lock_init(&f->f_lock);
 	eventpoll_init_file(f);
 	/* f->f_version: 0 */