Cap DERReencode recursion depth (GH #1353) - #1354
Open
Coralesoft wants to merge 1 commit into
Open
Conversation
DERReencode had no depth limit when walking nested constructed indefinite BER. A crafted chain of 0x30 0x80 sequences could recurse until the thread stack ran out. Add DERReencodeLimited and keep DERReencode as a depth-0 wrapper. The limit is 32 levels, matching OpenSSL ASN1_MAX_CONSTRUCTED_NEST. Deeper inputs now throw BERDecodeError.
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
1 participant
Add this suggestion to a batch that can be applied as a single commit.This suggestion is invalid because no changes were made to the code.Suggestions cannot be applied while the pull request is closed.Suggestions cannot be applied while viewing a subset of changes.Only one suggestion per line can be applied in a batch.Add this suggestion to a batch that can be applied as a single commit.Applying suggestions on deleted lines is not supported.You must change the existing code in this line in order to create a valid suggestion.Outdated suggestions cannot be applied.This suggestion has been applied or marked resolved.Suggestions cannot be applied from pending reviews.Suggestions cannot be applied on multi-line comments.Suggestions cannot be applied while the pull request is queued to merge.Suggestion cannot be applied right now. Please check back later.
Summary
Fixes #1353.
DERReencodewalks nested constructed indefinite BER without a depth limit, so a crafted chain of0x30 0x80sequences can exhaust the thread stack.PKCS8PrivateKeyimport reaches this path viaBERDecodeOptionalAttributes.The cap is 32 levels, matching OpenSSL
ASN1_MAX_CONSTRUCTED_NEST. Deeper inputs throwBERDecodeErrorinstead of recursing further.What changed
DERReencodeLimited(source, dest, depth)with the cap check at entry.DERReencodeas a depth-0 wrapper.