CVE-2022-23495

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.

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.

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. Additionally, use of the ProtoNode.SetCidBuilder() method to set non-functioning CidBuilder (such as one that refers to a multihash where an implementation of that hash function is not available) may cause the same methods to panic as a new CID is required but cannot be created.

### Impact 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. Additionally, use of the `ProtoNode#SetCidBuilder()` method to set a non-functioning `CidBuilder` (such as one that refers to a multihash where an implementation of that hash function is not available) may cause the same methods to panic as a new CID is required but cannot be created. ### Patches Releases involving fixes for this issue are [v0.8.0](https://github.com/ipfs/go-merkledag/releases/tag/v0.8.0) and [v0.8.1](https://github.com/ipfs/go-merkledag/releases/tag/v0.8.1). The recommended minimum version is **v0.8.1**. * Additional checks are performed on `ProtoNode` state changes to avoid the possibility of creating unencodeable forms, errors are returned where this is the case. * The builder passed in to `SetCidBuilder()` is inspected to attempt to determine if it is usable to generate CIDs, otherwise an error is returned. * The panics have been removed and replaced with default values (empty byte slice for `RawData()` and a default zero-bytes DAG-PB CID for methods involving CIDs). ### Workarounds These workarounds are available when using impacted versions to avoid panic conditions, and may be generally appropriate in order to provide meaningful feedback to users and avoid generating bad, or unexpected encoded data: * Sanitise inputs when allowing user-input to set a new `CidBuilder` on a `ProtoNode`. * Sanitise `Tsize` (`Link#Size`) values such that they are a reasonable byte-size for sub-DAGs where derived from user-input. ### References * https://github.com/ipfs/kubo/issues/9297 * https://github.com/ipfs/go-merkledag/issues/90 * https://github.com/ipfs/go-merkledag/releases/tag/v0.8.0 * https://github.com/ipfs/go-merkledag/pull/91 * https://github.com/ipfs/go-merkledag/pull/92 * https://github.com/ipfs/go-merkledag/pull/93 * https://github.com/ipfs/go-merkledag/releases/tag/v0.8.1 ### Credit Thanks to [@mrd0ll4r](https://github.com/mrd0ll4r) for reporting the original error to Kubo!

go-merkledag implementa la interfaz 'DAGService' y agrega dos tipos de nodos ipld, Protobuf y Raw para el proyecto ipfs. Un `ProtoNode` puede modificarse de tal manera que cause varios errores de codificación que provocarán pánico en llamadas a métodos comunes que no permiten devoluciones de errores. Un `ProtoNode` solo debería poder codificar en DAG-PB válido; intentar codificar formularios DAG-PB no válidos generará un error en el códec. La manipulación de un "ProtoNodo" existente (recién creado o decodificado) utilizando los métodos modificadores no tuvo en cuenta ciertos estados que colocarían el "ProtoNodo" en una forma no codificable. Debido a la conformidad con [`github.com/ipfs/go-block-format#Block`](https://pkg.go.dev/github.com/ipfs/go-block-format#Block) y [` github.com/ipfs/go-ipld-format#Node`](https://pkg.go.dev/github.com/ipfs/go-ipld-format#Node) interfaces, ciertos métodos, que internamente requieren una re-encode si el estado ha cambiado, entrará en pánico debido a la imposibilidad de devolver un error. Este problema se ha solucionado en varias solicitudes de extracción. Se recomienda a los usuarios que actualicen a la versión 0.8.1 para obtener un conjunto completo de correcciones. Los usuarios que no puedan actualizar pueden intentar mitigar este problema desinfectando las entradas cuando permiten que las entradas del usuario establezcan un nuevo `CidBuilder` en un `ProtoNode` y sanitizando los valores de `Tsize` (`Link#Size`) de modo que sean razonables. El tamaño de bytes para sub-DAG se deriva de la entrada del usuario.