Skip to content
New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Add advisory for openssl ssl::select_next_proto UAF #2217

Merged
merged 2 commits into from
Feb 2, 2025
Merged
Changes from all commits
Commits
File filter

Filter by extension

Filter by extension

Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
48 changes: 48 additions & 0 deletions crates/openssl/RUSTSEC-0000-0000.md
Original file line number Diff line number Diff line change
@@ -0,0 +1,48 @@
```toml
[advisory]
id = "RUSTSEC-0000-0000"
package = "openssl"
date = "2025-02-02"
url = "https://github.com/sfackler/rust-openssl/security/advisories/GHSA-rpmj-rpgj-qmpm"
references = ["https://github.com/sfackler/rust-openssl/pull/2360"]
categories = ["memory-exposure"]
keywords = ["ssl", "tls", "alpn"]
aliases = ["GHSA-rpmj-rpgj-qmpm"]

[affected.functions]
"openssl::ssl::select_next_proto" = [">= 0.10.0, < 0.10.70"]

[versions]
patched = [">= 0.10.70"]
```

# ssl::select_next_proto use after free

In `openssl` versions before `0.10.70`, `ssl::select_next_proto` can return a slice pointing into the `server` argument's buffer but with a lifetime bound to the `client` argument. In situations where the `server` buffer's lifetime is shorter than the `client` buffer's, this can cause a use after free. This could cause the server to crash or to return arbitrary memory contents to the client.

`openssl` 0.10.70 fixes the signature of `ssl::select_next_proto` to properly constrain the output buffer's lifetime to that of both input buffers.

In standard usage of `ssl::select_next_proto` in the callback passed to `SslContextBuilder::set_alpn_select_callback`, code is only affected if the `server` buffer is constructed *within* the callback. For example:

Not vulnerable - the server buffer has a `'static` lifetime:
```rust
builder.set_alpn_select_callback(|_, client_protos| {
ssl::select_next_proto(b"\x02h2", client_protos).ok_or_else(AlpnError::NOACK)
});
```

Not vulnerable - the server buffer outlives the handshake:
```rust
let server_protos = b"\x02h2".to_vec();
builder.set_alpn_select_callback(|_, client_protos| {
ssl::select_next_proto(&server_protos, client_protos).ok_or_else(AlpnError::NOACK)
});
```

Vulnerable - the server buffer is freed when the callback returns:
```rust
builder.set_alpn_select_callback(|_, client_protos| {
let server_protos = b"\x02h2".to_vec();
ssl::select_next_proto(&server_protos, client_protos).ok_or_else(AlpnError::NOACK)
});
```