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>
diff --git a/fs/btrfs/dir-item.c b/fs/btrfs/dir-item.c
index c24d615..5b6c6fb 100644
--- a/fs/btrfs/dir-item.c
+++ b/fs/btrfs/dir-item.c
@@ -484,3 +484,75 @@
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;
+}