[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 Signed-off-by: Christoph Lameter --- fs/ext2/dir.c | 46 ++++++++++++++++++++++++++++++++++++---------- include/linux/ext2_fs.h | 13 +++++++++++++ 2 files changed, 49 insertions(+), 10 deletions(-) diff --git a/fs/ext2/dir.c b/fs/ext2/dir.c index d72926f..4934860 100644 --- a/fs/ext2/dir.c +++ b/fs/ext2/dir.c @@ -97,9 +97,9 @@ static void ext2_check_page(struct page *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) @@ -111,6 +111,7 @@ static void ext2_check_page(struct page *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: @@ -287,6 +288,7 @@ ext2_readdir (struct file * filp, void * dirent, filldir_t filldir) 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"); @@ -309,8 +311,10 @@ ext2_readdir (struct file * filp, void * dirent, filldir_t filldir) 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; @@ -348,13 +352,14 @@ struct ext2_dir_entry_2 * ext2_find_entry (struct inode * dir, 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"); @@ -421,6 +426,7 @@ void ext2_set_link(struct inode *dir, struct ext2_dir_entry_2 *de, 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); @@ -452,6 +458,7 @@ int ext2_add_link (struct dentry *dentry, struct inode *inode) char *kaddr; unsigned from, to; int err; + char *page_start = NULL; /* * We take care of directory expansion in the same loop. @@ -466,16 +473,28 @@ int ext2_add_link (struct dentry *dentry, struct inode *inode) 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(mapping) - reclen; + if (chunk_size < EXT2_DIR_MAX_REC_LEN) { + kaddr += page_cache_size(mapping) - reclen; + } else { + kaddr += page_cache_size(mapping) - + (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; } @@ -505,6 +524,7 @@ int ext2_add_link (struct dentry *dentry, struct inode *inode) 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; @@ -547,6 +567,7 @@ int ext2_delete_entry (struct ext2_dir_entry_2 * dir, struct page * page ) 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__, @@ -604,7 +625,11 @@ int ext2_make_empty(struct inode *inode, struct inode *parent) 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); @@ -624,18 +649,19 @@ 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"); diff --git a/include/linux/ext2_fs.h b/include/linux/ext2_fs.h index 910a705..e8dd546 100644 --- a/include/linux/ext2_fs.h +++ b/include/linux/ext2_fs.h @@ -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 */ + -- 1.5.2.5 -- - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/