CVE-2021-41173: Github.com/ethereum/go ethereum Denial of Service Vulnerability

{
  "schema_version" : "1.4.0",
  "id" : "GHSA-59hh-656j-3p7v",
  "modified" : "2023-08-29T18:55:39Z",
  "published" : "2021-10-25T19:42:57Z",
  "aliases" : [ "CVE-2021-41173" ],
  "summary" : "Geth Node Vulnerable to DoS via maliciously crafted p2p message ",
  "details" : "### Impact\n\nA vulnerable node is susceptible to crash when processing a maliciously crafted message from a peer, via the `snap/1` protocol. The crash can be triggered by sending a malicious `snap/1` `GetTrieNodes` package. \n\n### Details\n\nOn September 21, 2021, geth-team member Gary Rong (@rjl493456442) found a way to crash the snap request handler . \nBy using this vulnerability, a peer connected on the `snap/1` protocol could cause a vulnerable node to crash with a `panic`.\n\nIn the `trie.TryGetNode` implementation, if the requested path is reached, the associated node will be returned. However the nilness is\nnot checked there.\n\n```golang\nfunc (t *Trie) tryGetNode(origNode node, path []byte, pos int) (item []byte, newnode node, resolved int, err error) {\n\t// If we reached the requested path, return the current node\n\tif pos >= len(path) {\n\t\t// Although we most probably have the original node expanded, encoding\n\t\t// that into consensus form can be nasty (needs to cascade down) and\n\t\t// time consuming. Instead, just pull the hash up from disk directly.\n\t\tvar hash hashNode\n\t\tif node, ok := origNode.(hashNode); ok {\n\t\t\thash = node\n\t\t} else {\n\t\t\thash, _ = origNode.cache()\n\t\t}\n```\nMore specifically the `origNode` can be nil(e.g. the child of fullnode) and system can panic at line `hash, _ = origNode.cache()`. \n\nWhen investigating this, @holiman tried to find it via fuzzing, which uncovered a second crasher, also related to the snap `GetTrieNodes` package. If the caller requests a storage trie:\n```golang\n\t\t\t\t// Storage slots requested, open the storage trie and retrieve from there\n\t\t\t\taccount, err := snap.Account(common.BytesToHash(pathset[0]))\n\t\t\t\tloads++ // always account database reads, even for failures\n\t\t\t\tif account == nil {\n\t\t\t\t\tbreak\n\t\t\t\t}\n\t\t\t\tstTrie, err := trie.NewSecure(common.BytesToHash(account.Root), triedb)\n```\nThe code assumes that `snap.Account` returns _either_ a non-nil response unless `error` is also provided. This is however not the case, since `snap.Account` can return `nil, nil`. \n\n### Patches\n\n```diff\n--- a/eth/protocols/snap/handler.go\n+++ b/eth/protocols/snap/handler.go\n@@ -469,7 +469,7 @@ func handleMessage(backend Backend, peer *Peer) error {\n \t\t\t\t// Storage slots requested, open the storage trie and retrieve from there\n \t\t\t\taccount, err := snap.Account(common.BytesToHash(pathset[0]))\n \t\t\t\tloads++ // always account database reads, even for failures\n-\t\t\t\tif err != nil {\n+\t\t\t\tif err != nil || account == nil {\n \t\t\t\t\tbreak\n \t\t\t\t}\n \t\t\t\tstTrie, err := trie.NewSecure(common.BytesToHash(account.Root), triedb)\ndiff --git a/trie/trie.go b/trie/trie.go\nindex 7ea7efa835..d0f0d4e2bc 100644\n--- a/trie/trie.go\n+++ b/trie/trie.go\n@@ -174,6 +174,10 @@ func (t *Trie) TryGetNode(path []byte) ([]byte, int, error) {\n }\n \n func (t *Trie) tryGetNode(origNode node, path []byte, pos int) (item []byte, newnode node, resolved int, err error) {\n+\t// If non-existent path requested, abort\n+\tif origNode == nil {\n+\t\treturn nil, nil, 0, nil\n+\t}\n \t// If we reached the requested path, return the current node\n \tif pos >= len(path) {\n \t\t// Although we most probably have the original node expanded, encoding\n@@ -193,10 +197,6 @@ func (t *Trie) tryGetNode(origNode node, path []byte, pos int) (item []byte, new\n \t}\n \t// Path still needs to be traversed, descend into children\n \tswitch n := (origNode).(type) {\n-\tcase nil:\n-\t\t// Non-existent path requested, abort\n-\t\treturn nil, nil, 0, nil\n-\n \tcase valueNode:\n \t\t// Path prematurely ended, abort\n \t\treturn nil, nil, 0, nil\n\n``` \nThe fixes were merged into [#23657](https://github.com/ethereum/go-ethereum/pull/23657), with commit [f1fd963](https://github.com/ethereum/go-ethereum/pull/23657/commits/f1fd963a5a965e643e52fcf805a2a02a323c32b8), and released as part of Geth [v1.10.9](https://github.com/ethereum/go-ethereum/tree/v1.10.9) on Sept 29, 2021. \n\n### Workarounds\n\nApply the patch above or upgrade to a version which is not vulnerable.\n\n### For more information\nIf you have any questions or comments about this advisory:\n* Open an issue in [go-ethereum](https://github.com/ethereum/go-ethereum/)\n* Email us at [security@ethereum.org](mailto:security@ethereum.org)\n",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:N/I:N/A:H"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "Go",
      "name" : "github.com/ethereum/go-ethereum"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "1.10.9"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/ethereum/go-ethereum/security/advisories/GHSA-59hh-656j-3p7v"
  }, {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2021-41173"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/ethereum/go-ethereum/pull/23657/commits/f1fd963a5a965e643e52fcf805a2a02a323c32b8"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/ethereum/go-ethereum/pull/23801"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/ethereum/go-ethereum/commit/e40b37718326b8b4873b3b00a0db2e6c6d9ea738"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/ethereum/go-ethereum"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/ethereum/go-ethereum/releases/tag/v1.10.9"
  }, {
    "type" : "WEB",
    "url" : "https://pkg.go.dev/vuln/GO-2022-0256"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-20" ],
    "severity" : "MODERATE",
    "github_reviewed" : true,
    "github_reviewed_at" : "2021-10-25T18:23:10Z",
    "nvd_published_at" : "2021-10-26T14:15:00Z"
  }
}