From: Eric Sandeen Subject: [PATCH] ext2: skip pages past number of blocks in ext2_find_entry Date: Thu, 21 Dec 2006 12:58:28 -0600 Message-ID: <458AD954.7020904@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Return-path: Received: from mx1.redhat.com ([66.187.233.31]:58710 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1423031AbWLUS6f (ORCPT ); Thu, 21 Dec 2006 13:58:35 -0500 To: Linux Kernel Mailing List , ext4 development Sender: linux-ext4-owner@vger.kernel.org List-Id: linux-ext4.vger.kernel.org This one was pointed out on the MOKB site: http://kernelfun.blogspot.com/2006/11/mokb-09-11-2006-linux-26x-ext2checkpage.html If a directory's i_size is corrupted, ext2_find_entry() will keep processing pages until the i_size is reached, even if there are no more blocks associated with the directory inode. This patch puts in some minimal sanity-checking so that we don't keep checking pages (and issuing errors) if we know there can be no more data to read, based on the block count of the directory inode. This is somewhat similar in approach to the ext3 patch I sent earlier this year. Thanks, -Eric Signed-off-by: Eric Sandeen Index: linux-2.6.19/fs/ext2/dir.c =================================================================== --- linux-2.6.19.orig/fs/ext2/dir.c +++ linux-2.6.19/fs/ext2/dir.c @@ -368,6 +368,14 @@ struct ext2_dir_entry_2 * ext2_find_entr } if (++n >= npages) n = 0; + /* next page is past the blocks we've got */ + if (unlikely(n > (dir->i_blocks >> (PAGE_CACHE_SHIFT - 9)))) { + ext2_error(dir->i_sb, __FUNCTION__, + "dir %lu size %lld exceeds block count %llu", + dir->i_ino, dir->i_size, + (unsigned long long)dir->i_blocks); + goto out; + } } while (n != start); out: return NULL;