When KTLS is enabled, multiple client's handshake will lead to unexpected eof while reading and data corrupt(possible memory leak).
Tested OpenSSL version: master, 3.0.0-alpha1 Kernel version: 5.4.43-1-MANJARO Reproduce step(using docker): sudo modprobe tls git clone https://github.com/openssl/openssl.git sudo docker run -it -v $(pwd)/openssl:/openssl archlinux # [In docker] pacman -Sy make gcc vim cd openssl ./config enable-ktls make build_sw -j4 pacman -Rdd openssl make install_sw cd / vim server.cpp # https://paste.ubuntu.com/p/fyhr6dDR7G/ vim client.cpp # https://paste.ubuntu.com/p/P2DjwWhTkf/ vim server.pem # https://paste.ubuntu.com/p/QttnVGsVSm/ vim serverkey.pem # https://paste.ubuntu.com/p/g6QR84wSfw/ g++ -c -o client.o client.cpp g++ -o client client.o -lssl -lcrypto g++ -c -o server.o server.cpp g++ -o server server.o -lssl -lcrypto export LD_LIBRARY_PATH=/usr/local/lib ./server & ./client You will see like this FP Vtest test test test Mljtest test test test test test test test Error creating SSL connection. err=ffffffff error:14000126:SSL routines::unexpected eof while reading When OpenSSL is compiled without ktls, the client will print test infinitely, but when enable ktls, some data are corrupted and sometimes result in unexpected eof while reading. Even when you remove SSL_write(ssl, reply, strlen(reply)); in server and RecvPacket(); in client, it will also result in unexpected eof while reading so I think there is something wrong with handshake procedure when ktls is enabled, maybe memory leak or UAF.
