Skip to content

src: fix TLSWrap lifetime bug in ALPN callback #49635

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.

Sign up for GitHub

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

Merged
nodejs-github-bot merged 1 commit into from
Oct 4, 2023
Merged

src: fix TLSWrap lifetime bug in ALPN callback #49635

Changes from all commits
Commits
Show all changes
1 commit
Select commit
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
src: fix TLSWrap lifetime bug in ALPN callback 
Retrieve the TLSWrap from the SSL object, not SSL_CTX.

A SSL_CTX object is the parent of zero or more SSL objects. TLSWrap is a
wrapper around SSL, SecureContext around SSL_CTX.

Node.js normally uses a SecureContext per TLSWrap but it is possible to
use a SecureContext object more than once.

It was therefore possible for an ALPN callback to use the wrong
(possibly already freed) TLSWrap object.

Having said that, while the bug is clear once you see it, I'm not able
to trigger it (and hence no test, not for lack of trying.)

None of the bug reporters were able to reliably reproduce it either so
the stars probably need to align just right in order to hit it.

Fixes: #47207
  • Loading branch information
@bnoordhuis
bnoordhuis committed Sep 13, 2023
commit 27c941f2bbcf5b4a45b918fc8a7b6275abf4fc47
8 changes: 5 additions & 3 deletions src/crypto/crypto_tls.cc
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -223,7 +223,7 @@ int SelectALPNCallback(
const unsigned char* in,
unsigned int inlen,
void* arg) {
TLSWrap* w = static_cast<TLSWrap*>(arg);
TLSWrap* w = static_cast<TLSWrap*>(SSL_get_app_data(s));
if (w->alpn_callback_enabled_) {
Environment* env = w->env();
HandleScope handle_scope(env->isolate());
Expand Down Expand Up @@ -1293,7 +1293,8 @@ void TLSWrap::EnableALPNCb(const FunctionCallbackInfo<Value>& args) {
wrap->alpn_callback_enabled_ = true;

SSL* ssl = wrap->ssl_.get();
SSL_CTX_set_alpn_select_cb(SSL_get_SSL_CTX(ssl), SelectALPNCallback, wrap);
SSL_CTX* ssl_ctx = SSL_get_SSL_CTX(ssl);
SSL_CTX_set_alpn_select_cb(ssl_ctx, SelectALPNCallback, nullptr);
}

void TLSWrap::GetServername(const FunctionCallbackInfo<Value>& args) {
Expand Down Expand Up @@ -1589,7 +1590,8 @@ void TLSWrap::SetALPNProtocols(const FunctionCallbackInfo<Value>& args) {
} else {
w->alpn_protos_ = std::vector<unsigned char>(
protos.data(), protos.data() + protos.length());
SSL_CTX_set_alpn_select_cb(SSL_get_SSL_CTX(ssl), SelectALPNCallback, w);
SSL_CTX* ssl_ctx = SSL_get_SSL_CTX(ssl);
SSL_CTX_set_alpn_select_cb(ssl_ctx, SelectALPNCallback, nullptr);
}
}

Expand Down