linux/fs/hfsplus/bfind.c
Eric Sandeen 9250f92597 hfsplus: handle more on-disk corruptions without oopsing
hfs seems prone to bad things when it encounters on disk corruption.  Many
values are read from disk, and used as lengths to memcpy, as an example.
This patch fixes up several of these problematic cases.

o sanity check the on-disk maximum key lengths on mount
  (these are set to a defined value at mkfs time and shouldn't differ)
o check on-disk node keylens against the maximum key length for each tree
o fix hfs_btree_open so that going out via free_tree: doesn't wind
  up in hfs_releasepage, which wants to follow the very pointer
  we were trying to set up:
	HFS_SB(sb)->cat_tree = hfs_btree_open()
    .
  failure gets to hfs_releasepage and tries to follow HFS_SB(sb)->cat_tree

Tested with the fsfuzzer; it survives more than it used to.

[hch: ported of commit cf05946250 from hfs]
[hch: added the fixes from 5581d018ed3493d226e7a4d645d9c8a5af6c36b]

Signed-off-by: Eric Sandeen <sandeen@redhat.com>
Signed-off-by: Christoph Hellwig <hch@tuxera.com>
2010-10-14 09:53:48 -04:00

223 lines
4.6 KiB
C

/*
* linux/fs/hfsplus/bfind.c
*
* Copyright (C) 2001
* Brad Boyer (flar@allandria.com)
* (C) 2003 Ardis Technologies <roman@ardistech.com>
*
* Search routines for btrees
*/
#include <linux/slab.h>
#include "hfsplus_fs.h"
int hfs_find_init(struct hfs_btree *tree, struct hfs_find_data *fd)
{
void *ptr;
fd->tree = tree;
fd->bnode = NULL;
ptr = kmalloc(tree->max_key_len * 2 + 4, GFP_KERNEL);
if (!ptr)
return -ENOMEM;
fd->search_key = ptr;
fd->key = ptr + tree->max_key_len + 2;
dprint(DBG_BNODE_REFS, "find_init: %d (%p)\n", tree->cnid, __builtin_return_address(0));
mutex_lock(&tree->tree_lock);
return 0;
}
void hfs_find_exit(struct hfs_find_data *fd)
{
hfs_bnode_put(fd->bnode);
kfree(fd->search_key);
dprint(DBG_BNODE_REFS, "find_exit: %d (%p)\n", fd->tree->cnid, __builtin_return_address(0));
mutex_unlock(&fd->tree->tree_lock);
fd->tree = NULL;
}
/* Find the record in bnode that best matches key (not greater than...)*/
int __hfs_brec_find(struct hfs_bnode *bnode, struct hfs_find_data *fd)
{
int cmpval;
u16 off, len, keylen;
int rec;
int b, e;
int res;
b = 0;
e = bnode->num_recs - 1;
res = -ENOENT;
do {
rec = (e + b) / 2;
len = hfs_brec_lenoff(bnode, rec, &off);
keylen = hfs_brec_keylen(bnode, rec);
if (keylen == 0) {
res = -EINVAL;
goto fail;
}
hfs_bnode_read(bnode, fd->key, off, keylen);
cmpval = bnode->tree->keycmp(fd->key, fd->search_key);
if (!cmpval) {
e = rec;
res = 0;
goto done;
}
if (cmpval < 0)
b = rec + 1;
else
e = rec - 1;
} while (b <= e);
if (rec != e && e >= 0) {
len = hfs_brec_lenoff(bnode, e, &off);
keylen = hfs_brec_keylen(bnode, e);
if (keylen == 0) {
res = -EINVAL;
goto fail;
}
hfs_bnode_read(bnode, fd->key, off, keylen);
}
done:
fd->record = e;
fd->keyoffset = off;
fd->keylength = keylen;
fd->entryoffset = off + keylen;
fd->entrylength = len - keylen;
fail:
return res;
}
/* Traverse a B*Tree from the root to a leaf finding best fit to key */
/* Return allocated copy of node found, set recnum to best record */
int hfs_brec_find(struct hfs_find_data *fd)
{
struct hfs_btree *tree;
struct hfs_bnode *bnode;
u32 nidx, parent;
__be32 data;
int height, res;
tree = fd->tree;
if (fd->bnode)
hfs_bnode_put(fd->bnode);
fd->bnode = NULL;
nidx = tree->root;
if (!nidx)
return -ENOENT;
height = tree->depth;
res = 0;
parent = 0;
for (;;) {
bnode = hfs_bnode_find(tree, nidx);
if (IS_ERR(bnode)) {
res = PTR_ERR(bnode);
bnode = NULL;
break;
}
if (bnode->height != height)
goto invalid;
if (bnode->type != (--height ? HFS_NODE_INDEX : HFS_NODE_LEAF))
goto invalid;
bnode->parent = parent;
res = __hfs_brec_find(bnode, fd);
if (!height)
break;
if (fd->record < 0)
goto release;
parent = nidx;
hfs_bnode_read(bnode, &data, fd->entryoffset, 4);
nidx = be32_to_cpu(data);
hfs_bnode_put(bnode);
}
fd->bnode = bnode;
return res;
invalid:
printk(KERN_ERR "hfs: inconsistency in B*Tree (%d,%d,%d,%u,%u)\n",
height, bnode->height, bnode->type, nidx, parent);
res = -EIO;
release:
hfs_bnode_put(bnode);
return res;
}
int hfs_brec_read(struct hfs_find_data *fd, void *rec, int rec_len)
{
int res;
res = hfs_brec_find(fd);
if (res)
return res;
if (fd->entrylength > rec_len)
return -EINVAL;
hfs_bnode_read(fd->bnode, rec, fd->entryoffset, fd->entrylength);
return 0;
}
int hfs_brec_goto(struct hfs_find_data *fd, int cnt)
{
struct hfs_btree *tree;
struct hfs_bnode *bnode;
int idx, res = 0;
u16 off, len, keylen;
bnode = fd->bnode;
tree = bnode->tree;
if (cnt < 0) {
cnt = -cnt;
while (cnt > fd->record) {
cnt -= fd->record + 1;
fd->record = bnode->num_recs - 1;
idx = bnode->prev;
if (!idx) {
res = -ENOENT;
goto out;
}
hfs_bnode_put(bnode);
bnode = hfs_bnode_find(tree, idx);
if (IS_ERR(bnode)) {
res = PTR_ERR(bnode);
bnode = NULL;
goto out;
}
}
fd->record -= cnt;
} else {
while (cnt >= bnode->num_recs - fd->record) {
cnt -= bnode->num_recs - fd->record;
fd->record = 0;
idx = bnode->next;
if (!idx) {
res = -ENOENT;
goto out;
}
hfs_bnode_put(bnode);
bnode = hfs_bnode_find(tree, idx);
if (IS_ERR(bnode)) {
res = PTR_ERR(bnode);
bnode = NULL;
goto out;
}
}
fd->record += cnt;
}
len = hfs_brec_lenoff(bnode, fd->record, &off);
keylen = hfs_brec_keylen(bnode, fd->record);
if (keylen == 0) {
res = -EINVAL;
goto out;
}
fd->keyoffset = off;
fd->keylength = keylen;
fd->entryoffset = off + keylen;
fd->entrylength = len - keylen;
hfs_bnode_read(bnode, fd->key, off, keylen);
out:
fd->bnode = bnode;
return res;
}