ProtoNode may be modified such that common method calls may panic in ipfs/go-merkledag

go-merkledag implements the 'DAGService' interface and adds two ipld node types, Protobuf and Raw for the ipfs project. A `ProtoNode` may be modified in such a way as to cause various encode errors which will trigger a panic on common method calls that don't allow for error returns. A `ProtoNode` should only be able to encode to valid DAG-PB, attempting to encode invalid DAG-PB forms will result in an error from the codec. Manipulation of an existing (newly created or decoded) `ProtoNode` using the modifier methods did not account for certain states that would place the `ProtoNode` into an unencodeable form. Due to conformance with the [`github.com/ipfs/go-block-format#Block`](https://pkg.go.dev/github.com/ipfs/go-block-format#Block) and [`github.com/ipfs/go-ipld-format#Node`](https://pkg.go.dev/github.com/ipfs/go-ipld-format#Node) interfaces, certain methods, which internally require a re-encode if state has changed, will panic due to the inability to return an error. This issue has been addressed across a number of pull requests. Users are advised to upgrade to version 0.8.1 for a complete set of fixes. Users unable to upgrade may attempt to mitigate this issue by sanitising inputs when allowing user-input to set a new `CidBuilder` on a `ProtoNode` and by sanitising `Tsize` (`Link#Size`) values such that they are a reasonable byte-size for sub-DAGs where derived from user-input.

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

对异常条件的处理不恰当

go-merkledag 安全漏洞

go-merkledag是IPFS开源的一个库。实现了 DAGService 接口。 go-merkledag存在安全漏洞，该漏洞源于其ProtoNode可能被修改为导致各种编码错误的方式，这些错误将在不允许错误返回的普通方法调用上触发恐慌。

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