With async crypto, we rely on tx_work to actually transmit records once encryption completes. But while send() is running, both the tx_lock and socket lock are held, so tx_work_handler cannot process the queue of encrypted records, and simply reschedules itself. During a large send(), this could last a long time, and use a lot of memory. Transmit any pending encrypted records before restarting the main loop of tls_sw_sendmsg_locked. Fixes: a42055e8d2c3 ("net/tls: Add support for async encryption of records for performance") Reported-by: Jann Horn Signed-off-by: Sabrina Dubroca --- Paolo suggests that we could also add memory accounting to sk_msg_alloc, and reclaim that memory just before pushing the data to tcp_sendmsg_locked. net/tls/tls_sw.c | 13 +++++++++++++ 1 file changed, 13 insertions(+) diff --git a/net/tls/tls_sw.c b/net/tls/tls_sw.c index e3d852091e7a..d17135369980 100644 --- a/net/tls/tls_sw.c +++ b/net/tls/tls_sw.c @@ -1152,6 +1152,13 @@ static int tls_sw_sendmsg_locked(struct sock *sk, struct msghdr *msg, } else if (ret != -EAGAIN) goto send_end; } + + /* Transmit if any encryptions have completed */ + if (test_and_clear_bit(BIT_TX_SCHEDULED, &ctx->tx_bitmask)) { + cancel_delayed_work(&ctx->tx_work.work); + tls_tx_records(sk, msg->msg_flags); + } + continue; rollback_iter: copied -= try_to_copy; @@ -1207,6 +1214,12 @@ static int tls_sw_sendmsg_locked(struct sock *sk, struct msghdr *msg, goto send_end; } } + + /* Transmit if any encryptions have completed */ + if (test_and_clear_bit(BIT_TX_SCHEDULED, &ctx->tx_bitmask)) { + cancel_delayed_work(&ctx->tx_work.work); + tls_tx_records(sk, msg->msg_flags); + } } continue; -- 2.51.0