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Date: Wed, 19 Dec 2007 16:33:13 -0600
From: Eric Sandeen <sandeen@...hat.com>
To: Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
Andrew Morton <akpm@...ux-foundation.org>
CC: Roman Zippel <zippel@...ux-m68k.org>
Subject: [PATCH] hfs: 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.
Signed-off-by: Eric Sandeen <sandeen@...hat.com>
---
Index: linux-2.6.24-rc3/fs/hfs/brec.c
===================================================================
--- linux-2.6.24-rc3.orig/fs/hfs/brec.c
+++ linux-2.6.24-rc3/fs/hfs/brec.c
@@ -44,10 +44,21 @@ u16 hfs_brec_keylen(struct hfs_bnode *no
recoff = hfs_bnode_read_u16(node, node->tree->node_size - (rec + 1) * 2);
if (!recoff)
return 0;
- if (node->tree->attributes & HFS_TREE_BIGKEYS)
+ if (node->tree->attributes & HFS_TREE_BIGKEYS) {
retval = hfs_bnode_read_u16(node, recoff) + 2;
- else
+ if (retval > node->tree->max_key_len + 2) {
+ printk(KERN_ERR "hfs: keylen %d too large\n",
+ retval);
+ retval = HFS_BAD_KEYLEN;
+ }
+ } else {
retval = (hfs_bnode_read_u8(node, recoff) | 1) + 1;
+ if (retval > node->tree->max_key_len + 1) {
+ printk(KERN_ERR "hfs: keylen %d too large\n",
+ retval);
+ retval = HFS_BAD_KEYLEN;
+ }
+ }
}
return retval;
}
Index: linux-2.6.24-rc3/fs/hfs/bfind.c
===================================================================
--- linux-2.6.24-rc3.orig/fs/hfs/bfind.c
+++ linux-2.6.24-rc3/fs/hfs/bfind.c
@@ -52,6 +52,11 @@ int __hfs_brec_find(struct hfs_bnode *bn
rec = (e + b) / 2;
len = hfs_brec_lenoff(bnode, rec, &off);
keylen = hfs_brec_keylen(bnode, rec);
+ if (keylen == HFS_BAD_KEYLEN) {
+ printk(KERN_ERR "hfs: keylen %d too long\n", keylen);
+ res = -EINVAL;
+ goto done;
+ }
hfs_bnode_read(bnode, fd->key, off, keylen);
cmpval = bnode->tree->keycmp(fd->key, fd->search_key);
if (!cmpval) {
@@ -67,6 +72,11 @@ int __hfs_brec_find(struct hfs_bnode *bn
if (rec != e && e >= 0) {
len = hfs_brec_lenoff(bnode, e, &off);
keylen = hfs_brec_keylen(bnode, e);
+ if (keylen == HFS_BAD_KEYLEN) {
+ printk(KERN_ERR "hfs: keylen %d too long\n", keylen);
+ res = -EINVAL;
+ goto done;
+ }
hfs_bnode_read(bnode, fd->key, off, keylen);
}
done:
@@ -198,6 +208,11 @@ int hfs_brec_goto(struct hfs_find_data *
len = hfs_brec_lenoff(bnode, fd->record, &off);
keylen = hfs_brec_keylen(bnode, fd->record);
+ if (keylen == HFS_BAD_KEYLEN) {
+ printk(KERN_ERR "hfs: keylen %d too long\n", keylen);
+ res = -EINVAL;
+ goto out;
+ }
fd->keyoffset = off;
fd->keylength = keylen;
fd->entryoffset = off + keylen;
Index: linux-2.6.24-rc3/fs/hfs/hfs.h
===================================================================
--- linux-2.6.24-rc3.orig/fs/hfs/hfs.h
+++ linux-2.6.24-rc3/fs/hfs/hfs.h
@@ -28,6 +28,8 @@
#define HFS_MAX_NAMELEN 128
#define HFS_MAX_VALENCE 32767U
+#define HFS_BAD_KEYLEN 0xFF
+
/* Meanings of the drAtrb field of the MDB,
* Reference: _Inside Macintosh: Files_ p. 2-61
*/
@@ -167,6 +169,9 @@ typedef union hfs_btree_key {
struct hfs_ext_key ext;
} hfs_btree_key;
+#define HFS_MAX_CAT_KEYLEN (sizeof(struct hfs_cat_key) - sizeof(u8))
+#define HFS_MAX_EXT_KEYLEN (sizeof(struct hfs_ext_key) - sizeof(u8))
+
typedef union hfs_btree_key btree_key;
struct hfs_extent {
Index: linux-2.6.24-rc3/fs/hfs/btree.c
===================================================================
--- linux-2.6.24-rc3.orig/fs/hfs/btree.c
+++ linux-2.6.24-rc3/fs/hfs/btree.c
@@ -81,6 +81,17 @@ struct hfs_btree *hfs_btree_open(struct
goto fail_page;
if (!tree->node_count)
goto fail_page;
+ if ((id == HFS_EXT_CNID) && (tree->max_key_len != HFS_MAX_EXT_KEYLEN)) {
+ printk(KERN_ERR "hfs: invalid extent max_key_len %d\n",
+ tree->max_key_len);
+ goto fail_page;
+ }
+ if ((id == HFS_CAT_CNID) && (tree->max_key_len != HFS_MAX_CAT_KEYLEN)) {
+ printk(KERN_ERR "hfs: invalid catalog max_key_len %d\n",
+ tree->max_key_len);
+ goto fail_page;
+ }
+
tree->node_size_shift = ffs(size) - 1;
tree->pages_per_bnode = (tree->node_size + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
@@ -89,9 +100,9 @@ struct hfs_btree *hfs_btree_open(struct
return tree;
fail_page:
- tree->inode->i_mapping->a_ops = &hfs_aops;
page_cache_release(page);
free_tree:
+ tree->inode->i_mapping->a_ops = &hfs_aops;
iput(tree->inode);
kfree(tree);
return NULL;
--
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