From: Mingming Cao Subject: [RFC 3/4] ext3: fix rec_len overflow with 64KB block size Date: Wed, 29 Aug 2007 17:48:10 -0700 Message-ID: <1188434890.3799.79.camel@localhost.localdomain> References: <20070828190551.415127746@sgi.com> <20070828190735.292638294@sgi.com> <1188432669.3799.35.camel@localhost.localdomain> Reply-To: cmm@us.ibm.com Mime-Version: 1.0 Content-Type: text/plain Content-Transfer-Encoding: 7bit Cc: linux-kernel@vger.kernel.org, adilger@clusterfs.com, sho@tnes.nec.co.jp, ext4 development To: clameter@sgi.com Return-path: Received: from e3.ny.us.ibm.com ([32.97.182.143]:55508 "EHLO e3.ny.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1761938AbXH3Ar4 (ORCPT ); Wed, 29 Aug 2007 20:47:56 -0400 In-Reply-To: <1188432669.3799.35.camel@localhost.localdomain> Sender: linux-ext4-owner@vger.kernel.org List-Id: linux-ext4.vger.kernel.org [3/4] ext3: fix rec_len overflow - prevent rec_len from overflow with 64KB blocksize Signed-off-by: Takashi Sato Signed-off-by: Mingming Cao --- fs/ext3/dir.c | 13 ++++--- fs/ext3/namei.c | 88 +++++++++++++++++++++++++++++++++++++++--------- include/linux/ext3_fs.h | 9 ++++ 3 files changed, 91 insertions(+), 19 deletions(-) Index: linux-2.6.23-rc3/fs/ext3/dir.c =================================================================== --- linux-2.6.23-rc3.orig/fs/ext3/dir.c 2007-08-12 21:25:24.000000000 -0700 +++ linux-2.6.23-rc3/fs/ext3/dir.c 2007-08-29 15:40:06.000000000 -0700 @@ -100,10 +100,11 @@ static int ext3_readdir(struct file * fi unsigned long offset; int i, stored; struct ext3_dir_entry_2 *de; - struct super_block *sb; int err; struct inode *inode = filp->f_path.dentry->d_inode; int ret = 0; + struct super_block *sb = inode->i_sb; + unsigned tail = sb->s_blocksize; sb = inode->i_sb; @@ -167,8 +168,11 @@ revalidate: * readdir(2), then we might be pointing to an invalid * dirent right now. Scan from the start of the block * to make sure. */ - if (filp->f_version != inode->i_version) { - for (i = 0; i < sb->s_blocksize && i < offset; ) { + if (tail > EXT3_DIR_MAX_REC_LEN) { + tail = EXT3_DIR_MAX_REC_LEN; + } + if (filp->f_version != inode->i_version) { + for (i = 0; i < tail && i < offset; ) { de = (struct ext3_dir_entry_2 *) (bh->b_data + i); /* It's too expensive to do a full @@ -189,7 +193,7 @@ revalidate: } while (!error && filp->f_pos < inode->i_size - && offset < sb->s_blocksize) { + && offset < tail) { de = (struct ext3_dir_entry_2 *) (bh->b_data + offset); if (!ext3_check_dir_entry ("ext3_readdir", inode, de, bh, offset)) { @@ -225,6 +229,7 @@ revalidate: } filp->f_pos += le16_to_cpu(de->rec_len); } + filp->f_pos = EXT3_DIR_ADJUST_TAIL_OFFS(filp->f_pos, sb->s_blocksize); offset = 0; brelse (bh); } Index: linux-2.6.23-rc3/fs/ext3/namei.c =================================================================== --- linux-2.6.23-rc3.orig/fs/ext3/namei.c 2007-08-12 21:25:24.000000000 -0700 +++ linux-2.6.23-rc3/fs/ext3/namei.c 2007-08-29 15:30:10.000000000 -0700 @@ -262,9 +262,13 @@ static struct stats dx_show_leaf(struct unsigned names = 0, space = 0; char *base = (char *) de; struct dx_hash_info h = *hinfo; + unsigned tail = size; printk("names: "); - while ((char *) de < base + size) + if (tail > EXT3_DIR_MAX_REC_LEN) { + tail = EXT3_DIR_MAX_REC_LEN; + } + while ((char *) de < base + tail) { if (de->inode) { @@ -677,8 +681,12 @@ static int dx_make_map (struct ext3_dir_ int count = 0; char *base = (char *) de; struct dx_hash_info h = *hinfo; + unsigned tail = size; - while ((char *) de < base + size) + if (tail > EXT3_DIR_MAX_REC_LEN) { + tail = EXT3_DIR_MAX_REC_LEN; + } + while ((char *) de < base + tail) { if (de->name_len && de->inode) { ext3fs_dirhash(de->name, de->name_len, &h); @@ -775,9 +783,13 @@ static inline int search_dirblock(struct int de_len; const char *name = dentry->d_name.name; int namelen = dentry->d_name.len; + unsigned tail = dir->i_sb->s_blocksize; de = (struct ext3_dir_entry_2 *) bh->b_data; - dlimit = bh->b_data + dir->i_sb->s_blocksize; + if (tail > EXT3_DIR_MAX_REC_LEN) { + tail = EXT3_DIR_MAX_REC_LEN; + } + dlimit = bh->b_data + tail; while ((char *) de < dlimit) { /* this code is executed quadratically often */ /* do minimal checking `by hand' */ @@ -1115,6 +1127,9 @@ static struct ext3_dir_entry_2* dx_pack_ unsigned rec_len = 0; prev = to = de; + if (size > EXT3_DIR_MAX_REC_LEN) { + size = EXT3_DIR_MAX_REC_LEN; + } while ((char*)de < base + size) { next = (struct ext3_dir_entry_2 *) ((char *) de + le16_to_cpu(de->rec_len)); @@ -1180,8 +1195,15 @@ static struct ext3_dir_entry_2 *do_split /* Fancy dance to stay within two buffers */ de2 = dx_move_dirents(data1, data2, map + split, count - split); de = dx_pack_dirents(data1,blocksize); - de->rec_len = cpu_to_le16(data1 + blocksize - (char *) de); - de2->rec_len = cpu_to_le16(data2 + blocksize - (char *) de2); + if (blocksize < EXT3_DIR_MAX_REC_LEN) { + de->rec_len = cpu_to_le16(data1 + blocksize - (char *) de); + de2->rec_len = cpu_to_le16(data2 + blocksize - (char *) de2); + } else { + de->rec_len = cpu_to_le16(data1 + EXT3_DIR_MAX_REC_LEN - + (char *) de); + de2->rec_len = cpu_to_le16(data2 + EXT3_DIR_MAX_REC_LEN - + (char *) de2); + } dxtrace(dx_show_leaf (hinfo, (struct ext3_dir_entry_2 *) data1, blocksize, 1)); dxtrace(dx_show_leaf (hinfo, (struct ext3_dir_entry_2 *) data2, blocksize, 1)); @@ -1236,11 +1258,15 @@ static int add_dirent_to_buf(handle_t *h unsigned short reclen; int nlen, rlen, err; char *top; + unsigned tail = dir->i_sb->s_blocksize; + if (tail > EXT3_DIR_MAX_REC_LEN) { + tail = EXT3_DIR_MAX_REC_LEN; + } reclen = EXT3_DIR_REC_LEN(namelen); if (!de) { de = (struct ext3_dir_entry_2 *)bh->b_data; - top = bh->b_data + dir->i_sb->s_blocksize - reclen; + top = bh->b_data + tail - reclen; while ((char *) de <= top) { if (!ext3_check_dir_entry("ext3_add_entry", dir, de, bh, offset)) { @@ -1354,13 +1380,21 @@ static int make_indexed_dir(handle_t *ha /* The 0th block becomes the root, move the dirents out */ fde = &root->dotdot; de = (struct ext3_dir_entry_2 *)((char *)fde + le16_to_cpu(fde->rec_len)); - len = ((char *) root) + blocksize - (char *) de; + if (blocksize < EXT3_DIR_MAX_REC_LEN) { + len = ((char *) root) + blocksize - (char *) de; + } else { + len = ((char *) root) + EXT3_DIR_MAX_REC_LEN - (char *) de; + } memcpy (data1, de, len); de = (struct ext3_dir_entry_2 *) data1; top = data1 + len; while ((char *)(de2=(void*)de+le16_to_cpu(de->rec_len)) < top) de = de2; - de->rec_len = cpu_to_le16(data1 + blocksize - (char *) de); + if (blocksize < EXT3_DIR_MAX_REC_LEN) { + de->rec_len = cpu_to_le16(data1 + blocksize - (char *) de); + } else { + de->rec_len = cpu_to_le16(data1 + EXT3_DIR_MAX_REC_LEN - (char *) de); + } /* Initialize the root; the dot dirents already exist */ de = (struct ext3_dir_entry_2 *) (&root->dotdot); de->rec_len = cpu_to_le16(blocksize - EXT3_DIR_REC_LEN(2)); @@ -1450,7 +1484,11 @@ static int ext3_add_entry (handle_t *han return retval; de = (struct ext3_dir_entry_2 *) bh->b_data; de->inode = 0; - de->rec_len = cpu_to_le16(blocksize); + if (blocksize < EXT3_DIR_MAX_REC_LEN) { + de->rec_len = cpu_to_le16(blocksize); + } else { + de->rec_len = cpu_to_le16(EXT3_DIR_MAX_REC_LEN); + } return add_dirent_to_buf(handle, dentry, inode, de, bh); } @@ -1514,7 +1552,12 @@ static int ext3_dx_add_entry(handle_t *h goto cleanup; node2 = (struct dx_node *)(bh2->b_data); entries2 = node2->entries; - node2->fake.rec_len = cpu_to_le16(sb->s_blocksize); + if (sb->s_blocksize < EXT3_DIR_MAX_REC_LEN) { + node2->fake.rec_len = cpu_to_le16(sb->s_blocksize); + } else { + node2->fake.rec_len = + cpu_to_le16(EXT3_DIR_MAX_REC_LEN); + } node2->fake.inode = 0; BUFFER_TRACE(frame->bh, "get_write_access"); err = ext3_journal_get_write_access(handle, frame->bh); @@ -1602,11 +1645,15 @@ static int ext3_delete_entry (handle_t * { struct ext3_dir_entry_2 * de, * pde; int i; + unsigned tail = bh->b_size; i = 0; pde = NULL; de = (struct ext3_dir_entry_2 *) bh->b_data; - while (i < bh->b_size) { + if (tail > EXT3_DIR_MAX_REC_LEN) { + tail = EXT3_DIR_MAX_REC_LEN; + } + while (i < tail) { if (!ext3_check_dir_entry("ext3_delete_entry", dir, de, bh, i)) return -EIO; if (de == de_del) { @@ -1766,7 +1813,11 @@ retry: de = (struct ext3_dir_entry_2 *) ((char *) de + le16_to_cpu(de->rec_len)); de->inode = cpu_to_le32(dir->i_ino); - de->rec_len = cpu_to_le16(inode->i_sb->s_blocksize-EXT3_DIR_REC_LEN(1)); + if (inode->i_sb->s_blocksize < EXT3_DIR_MAX_REC_LEN) { + de->rec_len = cpu_to_le16(inode->i_sb->s_blocksize-EXT3_DIR_REC_LEN(1)); + } else { + de->rec_len = cpu_to_le16(EXT3_DIR_MAX_REC_LEN-EXT3_DIR_REC_LEN(1)); + } de->name_len = 2; strcpy (de->name, ".."); ext3_set_de_type(dir->i_sb, de, S_IFDIR); @@ -1801,10 +1852,10 @@ static int empty_dir (struct inode * ino unsigned long offset; struct buffer_head * bh; struct ext3_dir_entry_2 * de, * de1; - struct super_block * sb; + struct super_block * sb = inode->i_sb; int err = 0; + unsigned tail = sb->s_blocksize; - sb = inode->i_sb; if (inode->i_size < EXT3_DIR_REC_LEN(1) + EXT3_DIR_REC_LEN(2) || !(bh = ext3_bread (NULL, inode, 0, 0, &err))) { if (err) @@ -1831,11 +1882,17 @@ static int empty_dir (struct inode * ino return 1; } offset = le16_to_cpu(de->rec_len) + le16_to_cpu(de1->rec_len); + if (offset == EXT3_DIR_MAX_REC_LEN) { + offset += sb->s_blocksize - EXT3_DIR_MAX_REC_LEN; + } de = (struct ext3_dir_entry_2 *) ((char *) de1 + le16_to_cpu(de1->rec_len)); + if (tail > EXT3_DIR_MAX_REC_LEN) { + tail = EXT3_DIR_MAX_REC_LEN; + } while (offset < inode->i_size ) { if (!bh || - (void *) de >= (void *) (bh->b_data+sb->s_blocksize)) { + (void *) de >= (void *) (bh->b_data + tail)) { err = 0; brelse (bh); bh = ext3_bread (NULL, inode, @@ -1862,6 +1919,7 @@ static int empty_dir (struct inode * ino return 0; } offset += le16_to_cpu(de->rec_len); + offset = EXT3_DIR_ADJUST_TAIL_OFFS(offset, sb->s_blocksize); de = (struct ext3_dir_entry_2 *) ((char *) de + le16_to_cpu(de->rec_len)); } Index: linux-2.6.23-rc3/include/linux/ext3_fs.h =================================================================== --- linux-2.6.23-rc3.orig/include/linux/ext3_fs.h 2007-08-29 15:22:29.000000000 -0700 +++ linux-2.6.23-rc3/include/linux/ext3_fs.h 2007-08-29 15:30:10.000000000 -0700 @@ -660,6 +660,15 @@ struct ext3_dir_entry_2 { #define EXT3_DIR_ROUND (EXT3_DIR_PAD - 1) #define EXT3_DIR_REC_LEN(name_len) (((name_len) + 8 + EXT3_DIR_ROUND) & \ ~EXT3_DIR_ROUND) +#define EXT3_DIR_MAX_REC_LEN 65532 + +/* + * Align a tail offset to the end of a directory block + */ +#define EXT3_DIR_ADJUST_TAIL_OFFS(offs, bsize) \ + ((((offs) & ((bsize) -1)) == EXT3_DIR_MAX_REC_LEN) ? \ + ((offs) + (bsize) - EXT3_DIR_MAX_REC_LEN):(offs)) + /* * Hash Tree Directory indexing * (c) Daniel Phillips, 2001