From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-ee0-f49.google.com ([74.125.83.49]:38574 "EHLO mail-ee0-f49.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751276Ab3ASP17 (ORCPT ); Sat, 19 Jan 2013 10:27:59 -0500 From: Cong Ding To: Chris Mason , linux-btrfs@vger.kernel.org, linux-kernel@vger.kernel.org Cc: Cong Ding Subject: [PATCH] btrfs: fix potential null pointer dereference bug Date: Sat, 19 Jan 2013 16:27:45 +0100 Message-Id: <1358609265-347-1-git-send-email-dinggnu@gmail.com> Sender: linux-btrfs-owner@vger.kernel.org List-ID: The bug happens when rb_node == NULL. It causes variable node to be NULL and then the NULL pointer is dereferenced this line: BUG_ON((struct btrfs_root *)node->data != root); Based on my analysis, function tree_search should not return NULL to variable rb_node in this case (otherwise here has to be something unknown thing wrong), so I replace "if (rb_node)" with UG_ON(!rb_node). Signed-off-by: Cong Ding --- fs/btrfs/relocation.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) diff --git a/fs/btrfs/relocation.c b/fs/btrfs/relocation.c index 17c306b..d674671 100644 --- a/fs/btrfs/relocation.c +++ b/fs/btrfs/relocation.c @@ -1263,10 +1263,11 @@ static int __update_reloc_root(struct btrfs_root *root, int del) spin_lock(&rc->reloc_root_tree.lock); rb_node = tree_search(&rc->reloc_root_tree.rb_root, root->commit_root->start); - if (rb_node) { - node = rb_entry(rb_node, struct mapping_node, rb_node); - rb_erase(&node->rb_node, &rc->reloc_root_tree.rb_root); - } + BUG_ON(!rb_node); + + node = rb_entry(rb_node, struct mapping_node, rb_node); + rb_erase(&node->rb_node, &rc->reloc_root_tree.rb_root); + spin_unlock(&rc->reloc_root_tree.lock); BUG_ON((struct btrfs_root *)node->data != root); -- 1.7.10.4