Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755190AbbBUAWP (ORCPT ); Fri, 20 Feb 2015 19:22:15 -0500 Received: from mail-pa0-f41.google.com ([209.85.220.41]:45979 "EHLO mail-pa0-f41.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754990AbbBUAWO (ORCPT ); Fri, 20 Feb 2015 19:22:14 -0500 Date: Sat, 21 Feb 2015 09:22:08 +0900 (JST) Message-Id: <20150221.092208.1795135375638032743.konishi.ryusuke@lab.ntt.co.jp> To: Andrew Morton Cc: linux-kernel@vger.kernel.org, linux-nilfs@vger.kernel.org Subject: Re: [PATCH 1/1] nilfs2: fix potential memory overrun on inode From: Ryusuke Konishi In-Reply-To: <20150220135842.0cd5c9338316a8a20b6a604a@linux-foundation.org> References: <1424439995-613-1-git-send-email-konishi.ryusuke@lab.ntt.co.jp> <1424439995-613-2-git-send-email-konishi.ryusuke@lab.ntt.co.jp> <20150220135842.0cd5c9338316a8a20b6a604a@linux-foundation.org> X-Mailer: Mew version 6.6 on Emacs 24.3 / Mule 6.0 (HANACHIRUSATO) Mime-Version: 1.0 Content-Type: Text/Plain; charset=us-ascii Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1796 Lines: 43 On Fri, 20 Feb 2015 13:58:42 -0800, Andrew Morton wrote: > On Fri, 20 Feb 2015 22:46:35 +0900 Ryusuke Konishi wrote: > >> Each inode of nilfs2 stores a root node of a b-tree, and it turned out >> to have a memory overrun issue: >> >> Each b-tree node of nilfs2 stores a set of key-value pairs and the >> number of them (in "bn_nchildren" member of nilfs_btree_node struct), >> as well as a few other "bn_*" members. >> >> Since the value of "bn_nchildren" is used for operations on the >> key-values within the b-tree node, it can cause memory access overrun >> if a large number is incorrectly set to "bn_nchildren". >> >> For instance, nilfs_btree_node_lookup() function determines the range >> of binary search with it, and too large "bn_nchildren" leads >> nilfs_btree_node_get_key() in that function to overrun. >> >> As for intermediate b-tree nodes, this is prevented by a sanity check >> performed when each node is read from a drive, however, no sanity >> check has been done for root nodes stored in inodes. >> >> This patch fixes the issue by adding missing sanity check against >> b-tree root nodes so that it's called when on-memory inodes are read >> from ifile, inode metadata file. > > How would one trigger this overrun? Mount an fs with a deliberately > corrupted/inconsistent fs image? Yes, this can be triggered by mounting an fs with a corrupted image deliberately or by chance. > Memory overrun sounds nasty so I'm thinking we add cc:stable to this > one. OK? Agreed. Ryusuke Konishi -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/