fix(crypto): mac_context_dtor should free MAC #9119
Conversation
This file contains 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
In the doc of EVP_MAC_fetch(), https://docs.openssl.org/3.0/man3/EVP_MAC "The returned value must eventually be freed with EVP_MAC_free(3)." This also ensures the same behaviour as in EVP_Q_mac which is used by NIF: crypto:mac/4. note, without this fix there is no memory leak as openssl3 returns the same addr of 'mac' (for the same MAC type), the side effect is the refcnt keeps bumping but I think it still good to have this fix also consider the case where the libcrypto is used by other NIF.
CT Test Results 2 files 14 suites 5m 55s ⏱️ Results for commit 5754f78. ♻️ This comment has been updated with latest results. To speed up review, make sure that you have read Contributing to Erlang/OTP and that all checks pass. See the TESTING and DEVELOPMENT HowTo guides for details about how to run test locally. Artifacts// Erlang/OTP Github Action Bot |
qzhuyan
added a commit
to qzhuyan/emqx
that referenced
this pull request
Nov 30, 2024
prefer to use crypto:pbkdf2_hmac to avoid refcnt overflow in OTP26: erlang/otp#9119
9 tasks
qzhuyan
commented
Dec 2, 2024
| @@ -498,6 +498,7 @@ struct mac_context | |||
| { | |||
| #if defined(HAS_3_0_API) | |||
| EVP_MAC_CTX *ctx; | |||
| EVP_MAC *mac; | |||
There was a problem hiding this comment.
I think we should better have a global var instead for different alg.
|
also have a drity but handy tool to reproduce the issue. |
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
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Outdated suggestions cannot be applied.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.
In the doc of EVP_MAC_fetch(), https://docs.openssl.org/3.0/man3/EVP_MAC
"The returned value must eventually be freed with EVP_MAC_free(3)."
This also ensures the same behaviour as in EVP_Q_mac which is used by NIF: crypto:mac/4.
note, without this fix there is no memory leak as openssl3 returns the same addr of 'mac' (for the same MAC type), the side effect is the refcnt keeps bumping but I think it still good to have this fix also consider the case where the libcrypto is used by other NIF.
update: 2nd thought, I think it may have the risk of refcnt overflow.
update: yes. it causes refcnt overflow and triggers double free.