linux-kernel - [PATCH] audit: fix mark refcounting

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Message-ID: <87obwof06x.fsf@tucsk.pomaz.szeredi.hu>
Date:	Mon, 07 Nov 2011 15:59:18 +0100
From:	Miklos Szeredi <miklos@...redi.hu>
To:	Eric Paris <eparis@...hat.com>, Al Viro <viro@...iv.linux.org.uk>
CC:	linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH] audit: fix mark refcounting

From: Miklos Szeredi <mszeredi@...e.cz>

Removing the parent of a watched file results in "kernel BUG at
fs/notify/mark.c:139".

To reproduce

  add "-w /tmp/audit/dir/watched_file" to audit.rules
  rm -rf /tmp/audit/dir

This is caused by fsnotify_destroy_mark() being called without an
extra reference taken by the caller.

Reported by Francesco Cosoleto here:

  https://bugzilla.novell.com/show_bug.cgi?id=689860

Signed-off-by: Miklos Szeredi <mszeredi@...e.cz>
CC: Al Viro <viro@...iv.linux.org.uk>
CC: Eric Paris <eparis@...hat.com>
CC: stable@...r.kernel.org
---
 kernel/audit_watch.c |    2 ++
 1 file changed, 2 insertions(+)

Index: linux.git/kernel/audit_watch.c
===================================================================
--- linux.git.orig/kernel/audit_watch.c	2011-09-13 16:08:20.000000000 +0200
+++ linux.git/kernel/audit_watch.c	2011-11-07 15:19:07.000000000 +0100
@@ -349,7 +349,9 @@ static void audit_remove_parent_watches(
 	}
 	mutex_unlock(&audit_filter_mutex);
 
+	audit_get_parent(parent);
 	fsnotify_destroy_mark(&parent->mark);
+	audit_put_parent(parent);
 }
 
 /* Get path information necessary for adding watches. */
--
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