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btrfs: Introduce btrfs_is_name_len_valid to avoid reading beyond boundary 

Introduce function btrfs_is_name_len_valid.

The function compares parameter @name_len with item boundary then
returns true if name_len is valid.

Signed-off-by: Su Yue <suy.fnst@cn.fujitsu.com>
Reviewed-by: David Sterba <dsterba@suse.com>
[ s/btrfs_leaf_data/BTRFS_LEAF_DATA_OFFSET/ ]
Signed-off-by: David Sterba <dsterba@suse.com>
This commit is contained in:
Su Yue 2017-06-06 17:57:00 +08:00 committed by David Sterba
parent 66b4993e95
commit 19c6dcbfa7
2 changed files with 74 additions and 0 deletions
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2
fs/btrfs/ctree.h
View File

@ -3042,6 +3042,8 @@ struct btrfs_dir_item *btrfs_match_dir_item_name(struct btrfs_fs_info *fs_info,
struct btrfs_path *path,
const char *name,
int name_len);
bool btrfs_is_name_len_valid(struct extent_buffer *leaf, int slot,
unsigned long start, u16 name_len);
/* orphan.c */
int btrfs_insert_orphan_item(struct btrfs_trans_handle *trans,

72
fs/btrfs/dir-item.c
View File

@ -484,3 +484,75 @@ int verify_dir_item(struct btrfs_fs_info *fs_info,
return 0;
}
bool btrfs_is_name_len_valid(struct extent_buffer *leaf, int slot,
unsigned long start, u16 name_len)
{
struct btrfs_fs_info *fs_info = leaf->fs_info;
struct btrfs_key key;
u32 read_start;
u32 read_end;
u32 item_start;
u32 item_end;
u32 size;
bool ret = true;
ASSERT(start > BTRFS_LEAF_DATA_OFFSET);
read_start = start - BTRFS_LEAF_DATA_OFFSET;
read_end = read_start + name_len;
item_start = btrfs_item_offset_nr(leaf, slot);
item_end = btrfs_item_end_nr(leaf, slot);
btrfs_item_key_to_cpu(leaf, &key, slot);
switch (key.type) {
case BTRFS_DIR_ITEM_KEY:
case BTRFS_XATTR_ITEM_KEY:
case BTRFS_DIR_INDEX_KEY:
size = sizeof(struct btrfs_dir_item);
break;
case BTRFS_INODE_REF_KEY:
size = sizeof(struct btrfs_inode_ref);
break;
case BTRFS_INODE_EXTREF_KEY:
size = sizeof(struct btrfs_inode_extref);
break;
case BTRFS_ROOT_REF_KEY:
case BTRFS_ROOT_BACKREF_KEY:
size = sizeof(struct btrfs_root_ref);
break;
default:
ret = false;
goto out;
}
if (read_start < item_start) {
ret = false;
goto out;
}
if (read_end > item_end) {
ret = false;
goto out;
}
/* there shall be item(s) before name */
if (read_start - item_start < size) {
ret = false;
goto out;
}
/*
* This may be the last item in the slot
* Or same type item(s) is left between read_end and item_end
*/
if (item_end != read_end && item_end - read_end < size) {
ret = false;
goto out;
}
out:
if (!ret)
btrfs_crit(fs_info, "invalid dir item name len: %u",
(unsigned int)name_len);
return ret;
}