From: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Date: Mon, 29 Dec 2014 13:00:19 +0000 (+0200)
Subject: 9p: do not crash on unknown lock status code
X-Git-Tag: v4.14-rc1~5545^2~5
X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=b642f7269bd40ae9abe9cff01581b2eb5e2c2287;p=platform%2Fkernel%2Flinux-rpi.git

9p: do not crash on unknown lock status code

Current 9p implementation will crash whole system if sees unknown lock
status code. It's trivial target for DOS: 9p server can produce such
code easily.

Let's fallback more gracefully: warning in dmesg + -ENOLCK.

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Signed-off-by: Dominique Martinet <dominique.martinet@cea.fr>
Signed-off-by: Eric Van Hensbergen <ericvh@gmail.com>
---

diff --git a/fs/9p/vfs_file.c b/fs/9p/vfs_file.c
index 8d29e1e..9612e5f 100644
--- a/fs/9p/vfs_file.c
+++ b/fs/9p/vfs_file.c
@@ -212,12 +212,13 @@ static int v9fs_file_do_lock(struct file *filp, int cmd, struct file_lock *fl)
 	case P9_LOCK_BLOCKED:
 		res = -EAGAIN;
 		break;
+	default:
+		WARN_ONCE(1, "unknown lock status code: %d\n", status);
+		/* fallthough */
 	case P9_LOCK_ERROR:
 	case P9_LOCK_GRACE:
 		res = -ENOLCK;
 		break;
-	default:
-		BUG();
 	}
 
 out_unlock: