net/http: limit canonical header cache by bytes, not entries (CVE-2022-41717)

[neild]

This is a PRIVATE issue for CVE-2022-41717 tracked in http://b/253471637.

net/http: limit canonical header cache by bytes, not entries

An attacker can cause excessive memory growth in a Go server accepting HTTP/2 requests.

HTTP/2 server connections contain a cache of HTTP header keys sent by the client. While the total number of entries in this cache is capped, an attacker sending very large keys can cause the server to allocate approximately 64 MiB per open connection.

This issue is also fixed in golang.org/x/net/http2 v0.4.0, for users manually configuring HTTP/2.

Thanks to Josselin Costanzi for reporting this issue.

[neild]

@gopherbot please open backport issues

[gopherbot]

Backport issue(s) opened: #57008 (for 1.18), #57009 (for 1.19).

Remember to create the cherry-pick CL(s) as soon as the patch is submitted to master, according to https://go.dev/wiki/MinorReleases.

[gopherbot]

Change https://go.dev/cl/455361 mentions this issue: [release-branch.go1.18] net/http: update bundled golang.org/x/net/http2

[gopherbot]

Change https://go.dev/cl/455363 mentions this issue: [release-branch.go1.19] net/http: update bundled golang.org/x/net/http2

[damz]

@neild @toothrot It seems like this has not made it yet to golang.org/x/net/http2.

[gopherbot]

Change https://go.dev/cl/455635 mentions this issue: http2: limit canonical header cache by bytes, not entries

[toothrot]

@damz correct, we always release Go first for private track issues.