From: Greg KH Subject: [patch 02/16] ext: Avoid printk floods in the face of directory corruption (CVE-2008-3528) Date: Fri, 7 Nov 2008 15:26:01 -0800 Message-ID: <20081107232601.GC4282@kroah.com> References: <20081107231848.995297975@mini.kroah.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Justin Forbes , Zwane Mwaikambo , Theodore Ts'o , Randy Dunlap , Dave Jones , Chuck Wolber , Chris Wedgwood , Michael Krufky , Chuck Ebbert , Domenico Andreoli , Willy Tarreau , Rodrigo Rubira Branco , Jake Edge , Eugene Teo , torvalds@linux-foundation.org, akpm@linux-foundation.org, alan@lxorguk.ukuu.org.uk, ext4 development , Eric Sandeen , Eugene Teo To: linux-kernel@vger.kernel.org, stable@kernel.org Return-path: Received: from kroah.org ([198.145.64.141]:47487 "EHLO coco.kroah.org" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1754430AbYKGX0n (ORCPT ); Fri, 7 Nov 2008 18:26:43 -0500 Content-Disposition: inline; filename="ext-avoid-printk-floods-in-the-face-of-directory-corruption.patch" In-Reply-To: <20081107232544.GA4282@kroah.com> Sender: linux-ext4-owner@vger.kernel.org List-ID: 2.6.25-stable review patch. If anyone has any objections, please let us know. ------------------ From: Eric Sandeen This is a trivial backport of the following upstream commits: - bd39597cbd42a784105a04010100e27267481c67 (ext2) - cdbf6dba28e8e6268c8420857696309470009fd9 (ext3) - 9d9f177572d9e4eba0f2e18523b44f90dd51fe74 (ext4) This addresses CVE-2008-3528 ext[234]: Avoid printk floods in the face of directory corruption Note: some people thinks this represents a security bug, since it might make the system go away while it is printing a large number of console messages, especially if a serial console is involved. Hence, it has been assigned CVE-2008-3528, but it requires that the attacker either has physical access to your machine to insert a USB disk with a corrupted filesystem image (at which point why not just hit the power button), or is otherwise able to convince the system administrator to mount an arbitrary filesystem image (at which point why not just include a setuid shell or world-writable hard disk device file or some such). Me, I think they're just being silly. --tytso Signed-off-by: Eric Sandeen Signed-off-by: "Theodore Ts'o" Cc: linux-ext4@vger.kernel.org Cc: Eugene Teo Signed-off-by: Greg Kroah-Hartman --- fs/ext2/dir.c | 60 +++++++++++++++++++++++++++++++++------------------------- fs/ext3/dir.c | 10 ++++++--- fs/ext4/dir.c | 11 +++++++--- 3 files changed, 50 insertions(+), 31 deletions(-) --- a/fs/ext2/dir.c +++ b/fs/ext2/dir.c @@ -103,7 +103,7 @@ static int ext2_commit_chunk(struct page return err; } -static void ext2_check_page(struct page *page) +static void ext2_check_page(struct page *page, int quiet) { struct inode *dir = page->mapping->host; struct super_block *sb = dir->i_sb; @@ -146,10 +146,10 @@ out: /* Too bad, we had an error */ Ebadsize: - ext2_error(sb, "ext2_check_page", - "size of directory #%lu is not a multiple of chunk size", - dir->i_ino - ); + if (!quiet) + ext2_error(sb, __func__, + "size of directory #%lu is not a multiple " + "of chunk size", dir->i_ino); goto fail; Eshort: error = "rec_len is smaller than minimal"; @@ -166,32 +166,36 @@ Espan: Einumber: error = "inode out of bounds"; bad_entry: - ext2_error (sb, "ext2_check_page", "bad entry in directory #%lu: %s - " - "offset=%lu, inode=%lu, rec_len=%d, name_len=%d", - dir->i_ino, error, (page->index<inode), - rec_len, p->name_len); + if (!quiet) + ext2_error(sb, __func__, "bad entry in directory #%lu: : %s - " + "offset=%lu, inode=%lu, rec_len=%d, name_len=%d", + dir->i_ino, error, (page->index<inode), + rec_len, p->name_len); goto fail; Eend: - p = (ext2_dirent *)(kaddr + offs); - ext2_error (sb, "ext2_check_page", - "entry in directory #%lu spans the page boundary" - "offset=%lu, inode=%lu", - dir->i_ino, (page->index<inode)); + if (!quiet) { + p = (ext2_dirent *)(kaddr + offs); + ext2_error(sb, "ext2_check_page", + "entry in directory #%lu spans the page boundary" + "offset=%lu, inode=%lu", + dir->i_ino, (page->index<inode)); + } fail: SetPageChecked(page); SetPageError(page); } -static struct page * ext2_get_page(struct inode *dir, unsigned long n) +static struct page * ext2_get_page(struct inode *dir, unsigned long n, + int quiet) { struct address_space *mapping = dir->i_mapping; struct page *page = read_mapping_page(mapping, n, NULL); if (!IS_ERR(page)) { kmap(page); if (!PageChecked(page)) - ext2_check_page(page); + ext2_check_page(page, quiet); if (PageError(page)) goto fail; } @@ -292,7 +296,7 @@ ext2_readdir (struct file * filp, void * for ( ; n < npages; n++, offset = 0) { char *kaddr, *limit; ext2_dirent *de; - struct page *page = ext2_get_page(inode, n); + struct page *page = ext2_get_page(inode, n, 0); if (IS_ERR(page)) { ext2_error(sb, __FUNCTION__, @@ -361,6 +365,7 @@ struct ext2_dir_entry_2 * ext2_find_entr struct page *page = NULL; struct ext2_inode_info *ei = EXT2_I(dir); ext2_dirent * de; + int dir_has_error = 0; if (npages == 0) goto out; @@ -374,7 +379,7 @@ struct ext2_dir_entry_2 * ext2_find_entr n = start; do { char *kaddr; - page = ext2_get_page(dir, n); + page = ext2_get_page(dir, n, dir_has_error); if (!IS_ERR(page)) { kaddr = page_address(page); de = (ext2_dirent *) kaddr; @@ -391,7 +396,9 @@ struct ext2_dir_entry_2 * ext2_find_entr de = ext2_next_entry(de); } ext2_put_page(page); - } + } else + dir_has_error = 1; + if (++n >= npages) n = 0; /* next page is past the blocks we've got */ @@ -414,7 +421,7 @@ found: struct ext2_dir_entry_2 * ext2_dotdot (struct inode *dir, struct page **p) { - struct page *page = ext2_get_page(dir, 0); + struct page *page = ext2_get_page(dir, 0, 0); ext2_dirent *de = NULL; if (!IS_ERR(page)) { @@ -487,7 +494,7 @@ int ext2_add_link (struct dentry *dentry for (n = 0; n <= npages; n++) { char *dir_end; - page = ext2_get_page(dir, n); + page = ext2_get_page(dir, n, 0); err = PTR_ERR(page); if (IS_ERR(page)) goto out; @@ -655,14 +662,17 @@ int ext2_empty_dir (struct inode * inode { struct page *page = NULL; unsigned long i, npages = dir_pages(inode); + int dir_has_error = 0; for (i = 0; i < npages; i++) { char *kaddr; ext2_dirent * de; - page = ext2_get_page(inode, i); + page = ext2_get_page(inode, i, dir_has_error); - if (IS_ERR(page)) + if (IS_ERR(page)) { + dir_has_error = 1; continue; + } kaddr = page_address(page); de = (ext2_dirent *)kaddr; --- a/fs/ext3/dir.c +++ b/fs/ext3/dir.c @@ -102,6 +102,7 @@ static int ext3_readdir(struct file * fi int err; struct inode *inode = filp->f_path.dentry->d_inode; int ret = 0; + int dir_has_error = 0; sb = inode->i_sb; @@ -148,9 +149,12 @@ static int ext3_readdir(struct file * fi * of recovering data when there's a bad sector */ if (!bh) { - ext3_error (sb, "ext3_readdir", - "directory #%lu contains a hole at offset %lu", - inode->i_ino, (unsigned long)filp->f_pos); + if (!dir_has_error) { + ext3_error(sb, __func__, "directory #%lu " + "contains a hole at offset %lld", + inode->i_ino, filp->f_pos); + dir_has_error = 1; + } /* corrupt size? Maybe no more blocks to read */ if (filp->f_pos > inode->i_blocks << 9) break; --- a/fs/ext4/dir.c +++ b/fs/ext4/dir.c @@ -102,6 +102,7 @@ static int ext4_readdir(struct file * fi int err; struct inode *inode = filp->f_path.dentry->d_inode; int ret = 0; + int dir_has_error = 0; sb = inode->i_sb; @@ -147,9 +148,13 @@ static int ext4_readdir(struct file * fi * of recovering data when there's a bad sector */ if (!bh) { - ext4_error (sb, "ext4_readdir", - "directory #%lu contains a hole at offset %lu", - inode->i_ino, (unsigned long)filp->f_pos); + if (!dir_has_error) { + ext4_error(sb, __func__, "directory #%lu " + "contains a hole at offset %Lu", + inode->i_ino, + (unsigned long long) filp->f_pos); + dir_has_error = 1; + } /* corrupt size? Maybe no more blocks to read */ if (filp->f_pos > inode->i_blocks << 9) break; --