From mboxrd@z Thu Jan 1 00:00:00 1970 From: tytso@mit.edu Subject: Re: [PATCH] resize2fs: fix uninit group test accessing invalid memory Date: Fri, 5 Feb 2010 22:35:39 -0500 Message-ID: <20100206033539.GA321@thunk.org> References: <4B5E0966.3040704@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: ext4 development To: Eric Sandeen Return-path: Received: from THUNK.ORG ([69.25.196.29]:38716 "EHLO thunker.thunk.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751914Ab0BFDfp (ORCPT ); Fri, 5 Feb 2010 22:35:45 -0500 Content-Disposition: inline In-Reply-To: <4B5E0966.3040704@redhat.com> Sender: linux-ext4-owner@vger.kernel.org List-ID: On Mon, Jan 25, 2010 at 03:13:10PM -0600, Eric Sandeen wrote: > Commit 74128f8d7e93fe633aa87951319a4afd252a4494 added tests > for uninit groups, but did it after the group counter > increment in 2 loops, so we were testing past the end > of the ->group_desc[] array: This patch is not correct; the test for uninit and the calculation for old_desc_blk needs to be for the next group, not the previous block. I believe this patch is the correct one instead. - Ted commit 40b09fbe01fac8722b699b29f796e18550d68c84 Author: Theodore Ts'o Date: Fri Feb 5 22:25:03 2010 -0500 resize2fs: Fix fix uninit group test accessing invalid memory Commit 74128f8 added tests for uninit groups, but it could access past the end of the group_desc[] array after processing the last group: ==19668== Invalid read of size 2 ==19668== at 0x40518C: resize_fs (resize2fs.c:1824) ==19668== by 0x405A46: main (main.c:451) ==19668== Address 0x5a0d002 is not stack'd, malloc'd or (recently) free'd ==19668== ==19668== Invalid read of size 2 ==19668== at 0x405391: resize_fs (resize2fs.c:1864) ==19668== by 0x405A46: main (main.c:451) ==19668== Address 0x5a0d002 is not stack'd, malloc'd or (recently) free'd ==19668== It was found by Eric Sandeen running the regression suite through valgrind. Signed-off-by: "Theodore Ts'o" diff --git a/resize/resize2fs.c b/resize/resize2fs.c index 75c4721..346fd53 100644 --- a/resize/resize2fs.c +++ b/resize/resize2fs.c @@ -1819,6 +1819,8 @@ static errcode_t ext2fs_calculate_summary_stats(ext2_filsys fs) group_free; ext2fs_group_desc_csum_set(fs, group); group++; + if (group >= fs->group_desc_count) + break; count = 0; group_free = 0; uninit = (fs->group_desc[group].bg_flags & @@ -1859,6 +1861,8 @@ static errcode_t ext2fs_calculate_summary_stats(ext2_filsys fs) group_free; ext2fs_group_desc_csum_set(fs, group); group++; + if (group >= fs->group_desc_count) + break; count = 0; group_free = 0; uninit = (fs->group_desc[group].bg_flags &