From 87acb4ef9b2991e1c453b78d71bce2ef994ef1ff Mon Sep 17 00:00:00 2001
From: David Woodhouse <David.Woodhouse@intel.com>
Date: Mon, 18 Aug 2008 22:50:22 +0100
Subject: Simplify btrfs_get_parent(), fix use-after-free bug
Date: Mon, 18 Aug 2008 22:50:22 +0100
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>
Signed-off-by: Chris Mason <chris.mason@oracle.com>
---
fs/btrfs/export.c | 26 +++++++++++---------------
1 file changed, 11 insertions(+), 15 deletions(-)
(limited to 'fs/btrfs/export.c')
diff --git a/fs/btrfs/export.c b/fs/btrfs/export.c
index 797b4cbc3786..a913b9befe68 100644
--- a/fs/btrfs/export.c
+++ b/fs/btrfs/export.c
@@ -147,7 +147,6 @@ static struct dentry *btrfs_get_parent(struct dentry *child)
struct btrfs_key key;
struct btrfs_path *path;
struct extent_buffer *leaf;
- u32 nritems;
int slot;
u64 objectid;
int ret;
@@ -156,27 +155,24 @@ static struct dentry *btrfs_get_parent(struct dentry *child)
key.objectid = dir->i_ino;
btrfs_set_key_type(&key, BTRFS_INODE_REF_KEY);
- key.offset = 0;
- ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
- BUG_ON(ret == 0);
- ret = 0;
+ key.offset = (u64)-1;
+ ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
leaf = path->nodes[0];
slot = path->slots[0];
- nritems = btrfs_header_nritems(leaf);
- if (slot >= nritems) {
- ret = btrfs_next_leaf(root, path);
- if (ret) {
- btrfs_free_path(path);
- goto out;
- }
- leaf = path->nodes[0];
- slot = path->slots[0];
+ if (ret < 0 || slot == 0) {
+ btrfs_free_path(path);
+ goto out;
}
+ /* btrfs_search_slot() returns the slot where we'd want to insert
+ an INODE_REF_KEY for parent inode #0xFFFFFFFFFFFFFFFF. The _real_
+ one, telling us what the parent inode _actually_ is, will be in
+ the slot _before_ the one that btrfs_search_slot() returns. */
+ slot--;
+ btrfs_item_key_to_cpu(leaf, &key, slot);
btrfs_free_path(path);
- btrfs_item_key_to_cpu(leaf, &key, slot);
if (key.objectid != dir->i_ino || key.type != BTRFS_INODE_REF_KEY)
goto out;
--
cgit