[4/4] ext4: fix rec_len overflow - prevent rec_len from overflow with 64KB blocksize Signed-off-by: Takashi Sato Signed-off-by: Mingming Cao --- fs/ext4/dir.c | 11 ++++-- fs/ext4/namei.c | 88 +++++++++++++++++++++++++++++++++++++++-------- include/linux/ext4_fs.h | 9 +++++ 3 files changed, 90 insertions(+), 18 deletions(-) diff --git a/fs/ext4/dir.c b/fs/ext4/dir.c index 93dd56c..8817cf4 100644 --- a/fs/ext4/dir.c +++ b/fs/ext4/dir.c @@ -100,10 +100,11 @@ static int ext4_readdir(struct file * filp, unsigned long offset; int i, stored; struct ext4_dir_entry_2 *de; - struct super_block *sb; int err; struct inode *inode = filp->f_path.dentry->d_inode; + struct super_block *sb = inode->i_sb; int ret = 0; + 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 (tail > EXT4_DIR_MAX_REC_LEN) { + tail = EXT4_DIR_MAX_REC_LEN; + } if (filp->f_version != inode->i_version) { - for (i = 0; i < sb->s_blocksize && i < offset; ) { + for (i = 0; i < tail && i < offset; ) { de = (struct ext4_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 ext4_dir_entry_2 *) (bh->b_data + offset); if (!ext4_check_dir_entry ("ext4_readdir", inode, de, bh, offset)) { @@ -226,6 +230,7 @@ revalidate: } filp->f_pos += le16_to_cpu(de->rec_len); } + filp->f_pos = EXT4_DIR_ADJUST_TAIL_OFFS(filp->f_pos, sb->s_blocksize); offset = 0; brelse (bh); } diff --git a/fs/ext4/namei.c b/fs/ext4/namei.c index da22497..e494b1b 100644 --- a/fs/ext4/namei.c +++ b/fs/ext4/namei.c @@ -262,9 +262,13 @@ static struct stats dx_show_leaf(struct dx_hash_info *hinfo, struct ext4_dir_ent 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 > EXT4_DIR_MAX_REC_LEN) { + tail = EXT4_DIR_MAX_REC_LEN; + } + while ((char *) de < base + tail) { if (de->inode) { @@ -677,8 +681,12 @@ static int dx_make_map (struct ext4_dir_entry_2 *de, int size, int count = 0; char *base = (char *) de; struct dx_hash_info h = *hinfo; + unsigned tail = size; - while ((char *) de < base + size) + if (tail > EXT4_DIR_MAX_REC_LEN) { + tail = EXT4_DIR_MAX_REC_LEN; + } + while ((char *) de < base + tail) { if (de->name_len && de->inode) { ext4fs_dirhash(de->name, de->name_len, &h); @@ -773,9 +781,13 @@ static inline int search_dirblock(struct buffer_head * bh, 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 ext4_dir_entry_2 *) bh->b_data; - dlimit = bh->b_data + dir->i_sb->s_blocksize; + if (tail > EXT4_DIR_MAX_REC_LEN) { + tail = EXT4_DIR_MAX_REC_LEN; + } + dlimit = bh->b_data + tail; while ((char *) de < dlimit) { /* this code is executed quadratically often */ /* do minimal checking `by hand' */ @@ -1113,6 +1125,9 @@ static struct ext4_dir_entry_2* dx_pack_dirents(char *base, int size) unsigned rec_len = 0; prev = to = de; + if (size > EXT4_DIR_MAX_REC_LEN) { + size = EXT4_DIR_MAX_REC_LEN; + } while ((char*)de < base + size) { next = (struct ext4_dir_entry_2 *) ((char *) de + le16_to_cpu(de->rec_len)); @@ -1178,8 +1193,15 @@ static struct ext4_dir_entry_2 *do_split(handle_t *handle, struct inode *dir, /* 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 < EXT4_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 + EXT4_DIR_MAX_REC_LEN - + (char *) de); + de2->rec_len = cpu_to_le16(data2 + EXT4_DIR_MAX_REC_LEN - + (char *) de2); + } dxtrace(dx_show_leaf (hinfo, (struct ext4_dir_entry_2 *) data1, blocksize, 1)); dxtrace(dx_show_leaf (hinfo, (struct ext4_dir_entry_2 *) data2, blocksize, 1)); @@ -1234,11 +1256,15 @@ static int add_dirent_to_buf(handle_t *handle, struct dentry *dentry, unsigned short reclen; int nlen, rlen, err; char *top; + unsigned tail = dir->i_sb->s_blocksize; + if (tail > EXT4_DIR_MAX_REC_LEN) { + tail = EXT4_DIR_MAX_REC_LEN; + } reclen = EXT4_DIR_REC_LEN(namelen); if (!de) { de = (struct ext4_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 (!ext4_check_dir_entry("ext4_add_entry", dir, de, bh, offset)) { @@ -1352,13 +1378,21 @@ static int make_indexed_dir(handle_t *handle, struct dentry *dentry, /* The 0th block becomes the root, move the dirents out */ fde = &root->dotdot; de = (struct ext4_dir_entry_2 *)((char *)fde + le16_to_cpu(fde->rec_len)); - len = ((char *) root) + blocksize - (char *) de; + if (blocksize < EXT4_DIR_MAX_REC_LEN) { + len = ((char *) root) + blocksize - (char *) de; + } else { + len = ((char *) root) + EXT4_DIR_MAX_REC_LEN - (char *) de; + } memcpy (data1, de, len); de = (struct ext4_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 < EXT4_DIR_MAX_REC_LEN) { + de->rec_len = cpu_to_le16(data1 + blocksize - (char *) de); + } else { + de->rec_len = cpu_to_le16(data1 + EXT4_DIR_MAX_REC_LEN - (char *) de); + } /* Initialize the root; the dot dirents already exist */ de = (struct ext4_dir_entry_2 *) (&root->dotdot); de->rec_len = cpu_to_le16(blocksize - EXT4_DIR_REC_LEN(2)); @@ -1448,7 +1482,11 @@ static int ext4_add_entry (handle_t *handle, struct dentry *dentry, return retval; de = (struct ext4_dir_entry_2 *) bh->b_data; de->inode = 0; - de->rec_len = cpu_to_le16(blocksize); + if (blocksize < EXT4_DIR_MAX_REC_LEN) { + de->rec_len = cpu_to_le16(blocksize); + } else { + de->rec_len = cpu_to_le16(EXT4_DIR_MAX_REC_LEN); + } return add_dirent_to_buf(handle, dentry, inode, de, bh); } @@ -1512,7 +1550,12 @@ static int ext4_dx_add_entry(handle_t *handle, struct dentry *dentry, 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 < EXT4_DIR_MAX_REC_LEN) { + node2->fake.rec_len = cpu_to_le16(sb->s_blocksize); + } else { + node2->fake.rec_len = + cpu_to_le16(EXT4_DIR_MAX_REC_LEN); + } node2->fake.inode = 0; BUFFER_TRACE(frame->bh, "get_write_access"); err = ext4_journal_get_write_access(handle, frame->bh); @@ -1600,11 +1643,15 @@ static int ext4_delete_entry (handle_t *handle, { struct ext4_dir_entry_2 * de, * pde; int i; + unsigned tail = bh->b_size; i = 0; pde = NULL; de = (struct ext4_dir_entry_2 *) bh->b_data; - while (i < bh->b_size) { + if (tail > EXT4_DIR_MAX_REC_LEN) { + tail = EXT4_DIR_MAX_REC_LEN; + } + while (i < tail) { if (!ext4_check_dir_entry("ext4_delete_entry", dir, de, bh, i)) return -EIO; if (de == de_del) { @@ -1793,7 +1840,11 @@ retry: de = (struct ext4_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-EXT4_DIR_REC_LEN(1)); + if (inode->i_sb->s_blocksize < EXT4_DIR_MAX_REC_LEN) { + de->rec_len = cpu_to_le16(inode->i_sb->s_blocksize-EXT4_DIR_REC_LEN(1)); + } else { + de->rec_len = cpu_to_le16(EXT4_DIR_MAX_REC_LEN-EXT4_DIR_REC_LEN(1)); + } de->name_len = 2; strcpy (de->name, ".."); ext4_set_de_type(dir->i_sb, de, S_IFDIR); @@ -1828,10 +1879,10 @@ static int empty_dir (struct inode * inode) unsigned long offset; struct buffer_head * bh; struct ext4_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 < EXT4_DIR_REC_LEN(1) + EXT4_DIR_REC_LEN(2) || !(bh = ext4_bread (NULL, inode, 0, 0, &err))) { if (err) @@ -1858,11 +1909,17 @@ static int empty_dir (struct inode * inode) return 1; } offset = le16_to_cpu(de->rec_len) + le16_to_cpu(de1->rec_len); + if (offset == EXT4_DIR_MAX_REC_LEN) { + offset += sb->s_blocksize - EXT4_DIR_MAX_REC_LEN; + } de = (struct ext4_dir_entry_2 *) ((char *) de1 + le16_to_cpu(de1->rec_len)); + if (tail > EXT4_DIR_MAX_REC_LEN) { + tail = EXT4_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 = ext4_bread (NULL, inode, @@ -1889,6 +1946,7 @@ static int empty_dir (struct inode * inode) return 0; } offset += le16_to_cpu(de->rec_len); + offset = EXT4_DIR_ADJUST_TAIL_OFFS(offset, sb->s_blocksize); de = (struct ext4_dir_entry_2 *) ((char *) de + le16_to_cpu(de->rec_len)); } diff --git a/include/linux/ext4_fs.h b/include/linux/ext4_fs.h index 9e4518b..52d7554 100644 --- a/include/linux/ext4_fs.h +++ b/include/linux/ext4_fs.h @@ -784,6 +784,15 @@ struct ext4_dir_entry_2 { #define EXT4_DIR_ROUND (EXT4_DIR_PAD - 1) #define EXT4_DIR_REC_LEN(name_len) (((name_len) + 8 + EXT4_DIR_ROUND) & \ ~EXT4_DIR_ROUND) +#define EXT4_DIR_MAX_REC_LEN 65532 + +/* + * Align a tail offset to the end of a directory block + */ +#define EXT4_DIR_ADJUST_TAIL_OFFS(offs, bsize) \ + ((((offs) & ((bsize) -1)) == EXT4_DIR_MAX_REC_LEN) ? \ + ((offs) + (bsize) - EXT4_DIR_MAX_REC_LEN):(offs)) + /* * Hash Tree Directory indexing * (c) Daniel Phillips, 2001 -- 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/