tor/changes/bug40391
Nick Mathewson 4c06c619fa Use a more secure hash function for the circuitmux hashtable.
Fixes bug 40931; bugfix on 0.2.4.4-alpha. Also tracked as
TROVE-2021-005.

This issue was reported by Jann Horn from Google's Project Zero.
2021-05-18 08:40:09 -04:00

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o Major bugfixes (security):
- Resist a hashtable-based CPU denial-of-service attack against
relays. Previously we used a naive unkeyed hash function to look up
circuits in a circuitmux object. An attacker could exploit this to
construct circuits with chosen circuit IDs in order to try to create
collisions and make the hash table inefficient. Now we use a SipHash
construction for this hash table instead. Fixes bug 40391; bugfix on
0.2.4.4-alpha. This issue is also tracked as TROVE-2021-005.
Reported by Jann Horn from Google's Project Zero.