From: Mingming Cao Subject: [RFC 2/4]ext2: fix rec_len overflow with 64KB block size Date: Wed, 29 Aug 2007 17:47:53 -0700 Message-ID: <1188434873.3799.78.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, linux-fsdevel@vger.kernel.org Return-path: In-Reply-To: <1188432669.3799.35.camel@localhost.localdomain> Sender: linux-fsdevel-owner@vger.kernel.org List-Id: linux-ext4.vger.kernel.org [2/4] ext2: fix rec_len overflow - prevent rec_len from overflow with 64KB blocksize Signed-off-by: Takashi Sato Signed-off-by: Mingming Cao --- fs/ext2/dir.c | 46 ++++++++++++++++++++++++++++++++++++---------- include/linux/ext2_fs.h | 13 +++++++++++++ 2 files changed, 49 insertions(+), 10 deletions(-) Index: linux-2.6.23-rc3/fs/ext2/dir.c =================================================================== --- linux-2.6.23-rc3.orig/fs/ext2/dir.c 2007-08-12 21:25:24.000000000 -0700 +++ linux-2.6.23-rc3/fs/ext2/dir.c 2007-08-29 15:29:51.000000000 -0700 @@ -94,9 +94,9 @@ static void ext2_check_page(struct page goto out; } for (offs = 0; offs <= limit - EXT2_DIR_REC_LEN(1); offs += rec_len) { + offs = EXT2_DIR_ADJUST_TAIL_OFFS(offs, chunk_size); p = (ext2_dirent *)(kaddr + offs); rec_len = le16_to_cpu(p->rec_len); - if (rec_len < EXT2_DIR_REC_LEN(1)) goto Eshort; if (rec_len & 3) @@ -108,6 +108,7 @@ static void ext2_check_page(struct page if (le32_to_cpu(p->inode) > max_inumber) goto Einumber; } + offs = EXT2_DIR_ADJUST_TAIL_OFFS(offs, chunk_size); if (offs != limit) goto Eend; out: @@ -283,6 +284,7 @@ ext2_readdir (struct file * filp, void * de = (ext2_dirent *)(kaddr+offset); limit = kaddr + ext2_last_byte(inode, n) - EXT2_DIR_REC_LEN(1); for ( ;(char*)de <= limit; de = ext2_next_entry(de)) { + de = EXT2_DIR_ADJUST_TAIL_ADDR(kaddr, de, sb->s_blocksize); if (de->rec_len == 0) { ext2_error(sb, __FUNCTION__, "zero-length directory entry"); @@ -305,8 +307,10 @@ ext2_readdir (struct file * filp, void * return 0; } } + filp->f_pos = EXT2_DIR_ADJUST_TAIL_OFFS(filp->f_pos, sb->s_blocksize); filp->f_pos += le16_to_cpu(de->rec_len); } + filp->f_pos = EXT2_DIR_ADJUST_TAIL_OFFS(filp->f_pos, sb->s_blocksize); ext2_put_page(page); } return 0; @@ -343,13 +347,14 @@ struct ext2_dir_entry_2 * ext2_find_entr start = 0; n = start; do { - char *kaddr; + char *kaddr, *page_start; page = ext2_get_page(dir, n); if (!IS_ERR(page)) { - kaddr = page_address(page); + kaddr = page_start = page_address(page); de = (ext2_dirent *) kaddr; kaddr += ext2_last_byte(dir, n) - reclen; while ((char *) de <= kaddr) { + de = EXT2_DIR_ADJUST_TAIL_ADDR(page_start, de, dir->i_sb->s_blocksize); if (de->rec_len == 0) { ext2_error(dir->i_sb, __FUNCTION__, "zero-length directory entry"); @@ -416,6 +421,7 @@ void ext2_set_link(struct inode *dir, st unsigned to = from + le16_to_cpu(de->rec_len); int err; + to = EXT2_DIR_ADJUST_TAIL_OFFS(to, inode->i_sb->s_blocksize); lock_page(page); err = page->mapping->a_ops->prepare_write(NULL, page, from, to); BUG_ON(err); @@ -446,6 +452,7 @@ int ext2_add_link (struct dentry *dentry char *kaddr; unsigned from, to; int err; + char *page_start = NULL; /* * We take care of directory expansion in the same loop. @@ -460,16 +467,28 @@ int ext2_add_link (struct dentry *dentry if (IS_ERR(page)) goto out; lock_page(page); - kaddr = page_address(page); + kaddr = page_start = page_address(page); dir_end = kaddr + ext2_last_byte(dir, n); de = (ext2_dirent *)kaddr; - kaddr += PAGE_CACHE_SIZE - reclen; + if (chunk_size < EXT2_DIR_MAX_REC_LEN) { + kaddr += PAGE_CACHE_SIZE - reclen; + } else { + kaddr += PAGE_CACHE_SIZE - + (chunk_size - EXT2_DIR_MAX_REC_LEN) - reclen; + } while ((char *)de <= kaddr) { + de = EXT2_DIR_ADJUST_TAIL_ADDR(page_start, de, chunk_size); if ((char *)de == dir_end) { /* We hit i_size */ name_len = 0; - rec_len = chunk_size; - de->rec_len = cpu_to_le16(chunk_size); + if (chunk_size < EXT2_DIR_MAX_REC_LEN) { + rec_len = chunk_size; + de->rec_len = cpu_to_le16(chunk_size); + } else { + rec_len = EXT2_DIR_MAX_REC_LEN; + de->rec_len = + cpu_to_le16(EXT2_DIR_MAX_REC_LEN); + } de->inode = 0; goto got_it; } @@ -499,6 +518,7 @@ int ext2_add_link (struct dentry *dentry got_it: from = (char*)de - (char*)page_address(page); to = from + rec_len; + to = EXT2_DIR_ADJUST_TAIL_OFFS(to, chunk_size); err = page->mapping->a_ops->prepare_write(NULL, page, from, to); if (err) goto out_unlock; @@ -541,6 +561,7 @@ int ext2_delete_entry (struct ext2_dir_e ext2_dirent * de = (ext2_dirent *) (kaddr + from); int err; + to = EXT2_DIR_ADJUST_TAIL_OFFS(to, inode->i_sb->s_blocksize); while ((char*)de < (char*)dir) { if (de->rec_len == 0) { ext2_error(inode->i_sb, __FUNCTION__, @@ -598,7 +619,11 @@ int ext2_make_empty(struct inode *inode, de = (struct ext2_dir_entry_2 *)(kaddr + EXT2_DIR_REC_LEN(1)); de->name_len = 2; - de->rec_len = cpu_to_le16(chunk_size - EXT2_DIR_REC_LEN(1)); + if (chunk_size < EXT2_DIR_MAX_REC_LEN) { + de->rec_len = cpu_to_le16(chunk_size - EXT2_DIR_REC_LEN(1)); + } else { + de->rec_len = cpu_to_le16(EXT2_DIR_MAX_REC_LEN - EXT2_DIR_REC_LEN(1)); + } de->inode = cpu_to_le32(parent->i_ino); memcpy (de->name, "..\0", 4); ext2_set_de_type (de, inode); @@ -618,18 +643,19 @@ int ext2_empty_dir (struct inode * inode unsigned long i, npages = dir_pages(inode); for (i = 0; i < npages; i++) { - char *kaddr; + char *kaddr, *page_start; ext2_dirent * de; page = ext2_get_page(inode, i); if (IS_ERR(page)) continue; - kaddr = page_address(page); + kaddr = page_start = page_address(page); de = (ext2_dirent *)kaddr; kaddr += ext2_last_byte(inode, i) - EXT2_DIR_REC_LEN(1); while ((char *)de <= kaddr) { + de = EXT2_DIR_ADJUST_TAIL_ADDR(page_start, de, inode->i_sb->s_blocksize); if (de->rec_len == 0) { ext2_error(inode->i_sb, __FUNCTION__, "zero-length directory entry"); Index: linux-2.6.23-rc3/include/linux/ext2_fs.h =================================================================== --- linux-2.6.23-rc3.orig/include/linux/ext2_fs.h 2007-08-29 15:22:29.000000000 -0700 +++ linux-2.6.23-rc3/include/linux/ext2_fs.h 2007-08-29 15:29:51.000000000 -0700 @@ -557,5 +557,18 @@ enum { #define EXT2_DIR_ROUND (EXT2_DIR_PAD - 1) #define EXT2_DIR_REC_LEN(name_len) (((name_len) + 8 + EXT2_DIR_ROUND) & \ ~EXT2_DIR_ROUND) +#define EXT2_DIR_MAX_REC_LEN 65532 + +/* + * Align a tail offset(address) to the end of a directory block + */ +#define EXT2_DIR_ADJUST_TAIL_OFFS(offs, bsize) \ + ((((offs) & ((bsize) -1)) == EXT2_DIR_MAX_REC_LEN) ? \ + ((offs) + (bsize) - EXT2_DIR_MAX_REC_LEN):(offs)) + +#define EXT2_DIR_ADJUST_TAIL_ADDR(page, de, bsize) \ + (((((char*)(de) - (page)) & ((bsize) - 1)) == EXT2_DIR_MAX_REC_LEN) ? \ + ((ext2_dirent*)((char*)(de) + (bsize) - EXT2_DIR_MAX_REC_LEN)):(de)) #endif /* _LINUX_EXT2_FS_H */ +