ssh: reject certificate signature keys before recursing

parseCert parsed a certificate's SignatureKey by calling ParsePublicKey
again, and only afterwards rejected a certificate used as a signing key.
For a chain of nested certificates this recursed once per level, so a key
with enough nesting exhausted the goroutine stack and crashed with a fatal
stack overflow that recover cannot catch.

Reject the signature key by its declared algorithm before parsing it, which
bounds parsing.

Fixes golang/go#80414

Change-Id: Id51401aae15bfbec006c03ab97635a3b68bd6058
Reviewed-on: https://go-review.googlesource.com/c/crypto/+/802145
Auto-Submit: Nicola Murino <nicola.murino@gmail.com>
Reviewed-by: Carlos Amedee <carlos@golang.org>
LUCI-TryBot-Result: golang-scoped@luci-project-accounts.iam.gserviceaccount.com <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Cherry Mui <cherryyz@google.com>
Reviewed-by: Filippo Valsorda <filippo@golang.org>
2 files changed
tree: 90c9d5974f4a63e764bf3eccf89dfd98cc08526b
  1. acme/
  2. argon2/
  3. bcrypt/
  4. blake2b/
  5. blake2s/
  6. blowfish/
  7. bn256/
  8. cast5/
  9. chacha20/
  10. chacha20poly1305/
  11. cryptobyte/
  12. curve25519/
  13. ed25519/
  14. hkdf/
  15. internal/
  16. md4/
  17. nacl/
  18. ocsp/
  19. openpgp/
  20. otr/
  21. pbkdf2/
  22. pkcs12/
  23. poly1305/
  24. ripemd160/
  25. salsa20/
  26. scrypt/
  27. sha3/
  28. ssh/
  29. tea/
  30. twofish/
  31. x509roots/
  32. xtea/
  33. xts/
  34. .gitattributes
  35. .gitignore
  36. codereview.cfg
  37. CONTRIBUTING.md
  38. go.mod
  39. go.sum
  40. LICENSE
  41. PATENTS
  42. README.md
README.md

Go Cryptography

Go Reference

This repository holds supplementary Go cryptography packages.

Report Issues / Send Patches

This repository uses Gerrit for code changes. To learn how to submit changes to this repository, see https://go.dev/doc/contribute.

The git repository is https://go.googlesource.com/crypto.

The main issue tracker for the crypto repository is located at https://go.dev/issues. Prefix your issue with “x/crypto:” in the subject line, so it is easy to find.

Note that contributions to the cryptography package receive additional scrutiny due to their sensitive nature. Patches may take longer than normal to receive feedback.