ext2: fix rec_len overflow From: Takashi Sato prevent rec_len from overflow with 64KB blocksize Signed-off-by: Takashi Sato --- fs/ext2/dir.c | 56 +++++++++++++++++++++++++++++++++++++++--------- include/linux/ext2_fs.h | 13 +++++++++++ 2 files changed, 59 insertions(+), 10 deletions(-) Index: linux-2.6.23-rc5/fs/ext2/dir.c =================================================================== --- linux-2.6.23-rc5.orig/fs/ext2/dir.c 2007-09-12 16:16:57.000000000 -0700 +++ linux-2.6.23-rc5/fs/ext2/dir.c 2007-09-12 16:33:10.000000000 -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 +284,8 @@ 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 +308,12 @@ 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 +350,16 @@ 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); + page_start = page_address(page); + kaddr = page_start; 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 +426,7 @@ 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 +457,7 @@ 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 +472,30 @@ int ext2_add_link (struct dentry *dentry if (IS_ERR(page)) goto out; lock_page(page); - kaddr = page_address(page); + page_start = page_address(page); + kaddr = page_start; 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 +525,7 @@ 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 +568,7 @@ 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 +626,12 @@ 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 +651,21 @@ 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); + page_start = page_address(page); + kaddr = page_start; 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-rc5/include/linux/ext2_fs.h =================================================================== --- linux-2.6.23-rc5.orig/include/linux/ext2_fs.h 2007-09-12 16:25:40.000000000 -0700 +++ linux-2.6.23-rc5/include/linux/ext2_fs.h 2007-09-12 16:34:07.000000000 -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 */ +