From: Randy Dunlap Subject: Re: [PATCH] ext2: skip pages past number of blocks in ext2_find_entry Date: Thu, 21 Dec 2006 11:05:49 -0800 Message-ID: <20061221110549.bf336c02.randy.dunlap@oracle.com> References: <458AD954.7020904@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Cc: Linux Kernel Mailing List , ext4 development Return-path: To: Eric Sandeen In-Reply-To: <458AD954.7020904@redhat.com> Sender: linux-kernel-owner@vger.kernel.org List-Id: linux-ext4.vger.kernel.org On Thu, 21 Dec 2006 12:58:28 -0600 Eric Sandeen wrote: > 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; Please don't hide the goto; un-indent 1 tab stop. > + } > } while (n != start); > out: > return NULL; --- ~Randy