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: v2.6.34.10~152
X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=d9ea040985cf6fe106e183e38487f7d42badc4d5;p=karo-tx-linux.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: Paul Gortmaker <paul.gortmaker@windriver.com>
---

diff --git a/fs/file_table.c b/fs/file_table.c
index 32d12b78bac8..d4be17f188b4 100644
--- a/fs/file_table.c
+++ b/fs/file_table.c
@@ -123,13 +123,13 @@ 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 */