linux-stable/fs/hfs/bfind.c
Desmond Cheong Zhi Xi b3b2177a2d hfs: add lock nesting notation to hfs_find_init
Syzbot reports a possible recursive lock in [1].

This happens due to missing lock nesting information.  From the logs, we
see that a call to hfs_fill_super is made to mount the hfs filesystem.
While searching for the root inode, the lock on the catalog btree is
grabbed.  Then, when the parent of the root isn't found, a call to
__hfs_bnode_create is made to create the parent of the root.  This
eventually leads to a call to hfs_ext_read_extent which grabs a lock on
the extents btree.

Since the order of locking is catalog btree -> extents btree, this lock
hierarchy does not lead to a deadlock.

To tell lockdep that this locking is safe, we add nesting notation to
distinguish between catalog btrees, extents btrees, and attributes
btrees (for HFS+).  This has already been done in hfsplus.

Link: https://syzkaller.appspot.com/bug?id=f007ef1d7a31a469e3be7aeb0fde0769b18585db [1]
Link: https://lkml.kernel.org/r/20210701030756.58760-4-desmondcheongzx@gmail.com
Signed-off-by: Desmond Cheong Zhi Xi <desmondcheongzx@gmail.com>
Reported-by: syzbot+b718ec84a87b7e73ade4@syzkaller.appspotmail.com
Tested-by: syzbot+b718ec84a87b7e73ade4@syzkaller.appspotmail.com
Reviewed-by: Viacheslav Dubeyko <slava@dubeyko.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Gustavo A. R. Silva <gustavoars@kernel.org>
Cc: Shuah Khan <skhan@linuxfoundation.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-07-15 10:13:49 -07:00

237 lines
4.9 KiB
C

// SPDX-License-Identifier: GPL-2.0
/*
* linux/fs/hfs/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 "btree.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;
hfs_dbg(BNODE_REFS, "find_init: %d (%p)\n",
tree->cnid, __builtin_return_address(0));
switch (tree->cnid) {
case HFS_CAT_CNID:
mutex_lock_nested(&tree->tree_lock, CATALOG_BTREE_MUTEX);
break;
case HFS_EXT_CNID:
mutex_lock_nested(&tree->tree_lock, EXTENTS_BTREE_MUTEX);
break;
case HFS_ATTR_CNID:
mutex_lock_nested(&tree->tree_lock, ATTR_BTREE_MUTEX);
break;
default:
return -EINVAL;
}
return 0;
}
void hfs_find_exit(struct hfs_find_data *fd)
{
hfs_bnode_put(fd->bnode);
kfree(fd->search_key);
hfs_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:
pr_err("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;
}