From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756350Ab2HUTEO (ORCPT ); Tue, 21 Aug 2012 15:04:14 -0400 Received: from mail-wi0-f172.google.com ([209.85.212.172]:49832 "EHLO mail-wi0-f172.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755822Ab2HUTEI (ORCPT ); Tue, 21 Aug 2012 15:04:08 -0400 From: Miklos Szeredi To: torvalds@linux-foundation.org Cc: eparis@redhat.com, viro@ZenIV.linux.org.uk, linux-kernel@vger.kernel.org, mszeredi@suse.cz, stable@vger.kernel.org Subject: [PATCH 2/3] audit: fix refcounting in audit-tree Date: Tue, 21 Aug 2012 21:03:58 +0200 Message-Id: <1345575839-9389-3-git-send-email-miklos@szeredi.hu> X-Mailer: git-send-email 1.7.7 In-Reply-To: <1345575839-9389-1-git-send-email-miklos@szeredi.hu> References: <1345575839-9389-1-git-send-email-miklos@szeredi.hu> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Miklos Szeredi Refcounting of fsnotify_mark in audit tree is broken. E.g: refcount create_chunk alloc_chunk 1 fsnotify_add_mark 2 untag_chunk fsnotify_get_mark 3 fsnotify_destroy_mark audit_tree_freeing_mark 2 fsnotify_put_mark 1 fsnotify_put_mark 0 via destroy_list fsnotify_mark_destroy -1 This was reported by various people as triggering Oops when stopping auditd. We could just remove the put_mark from audit_tree_freeing_mark() but that would break freeing via inode destruction. So this patch simply omits a put_mark after calling destroy_mark or adds a get_mark before. The additional get_mark is necessary where there's no other put_mark after fsnotify_destroy_mark() since it assumes that the caller is holding a reference (or the inode is keeping the mark pinned, not the case here AFAICS). Signed-off-by: Miklos Szeredi Reported-by: Valentin Avram Reported-by: Peter Moody Acked-by: Eric Paris CC: stable@vger.kernel.org --- kernel/audit_tree.c | 5 ++--- 1 files changed, 2 insertions(+), 3 deletions(-) diff --git a/kernel/audit_tree.c b/kernel/audit_tree.c index 69a5851..2b2ffff 100644 --- a/kernel/audit_tree.c +++ b/kernel/audit_tree.c @@ -250,7 +250,6 @@ static void untag_chunk(struct node *p) spin_unlock(&hash_lock); spin_unlock(&entry->lock); fsnotify_destroy_mark(entry); - fsnotify_put_mark(entry); goto out; } @@ -293,7 +292,6 @@ static void untag_chunk(struct node *p) spin_unlock(&hash_lock); spin_unlock(&entry->lock); fsnotify_destroy_mark(entry); - fsnotify_put_mark(entry); goto out; Fallback: @@ -332,6 +330,7 @@ static int create_chunk(struct inode *inode, struct audit_tree *tree) spin_unlock(&hash_lock); chunk->dead = 1; spin_unlock(&entry->lock); + fsnotify_get_mark(entry); fsnotify_destroy_mark(entry); fsnotify_put_mark(entry); return 0; @@ -412,6 +411,7 @@ static int tag_chunk(struct inode *inode, struct audit_tree *tree) spin_unlock(&chunk_entry->lock); spin_unlock(&old_entry->lock); + fsnotify_get_mark(chunk_entry); fsnotify_destroy_mark(chunk_entry); fsnotify_put_mark(chunk_entry); @@ -445,7 +445,6 @@ static int tag_chunk(struct inode *inode, struct audit_tree *tree) spin_unlock(&old_entry->lock); fsnotify_destroy_mark(old_entry); fsnotify_put_mark(old_entry); /* pair to fsnotify_find mark_entry */ - fsnotify_put_mark(old_entry); /* and kill it */ return 0; } -- 1.7.7