Commit 7f846c65 authored Oct 14, 2025 by Sabrina Dubroca Committed by Jakub Kicinski Oct 15, 2025

tls: don't rely on tx_work during send()

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: a42055e8 ("net/tls: Add support for async encryption of records for performance")
Reported-by: Jann Horn <jannh@google.com>
Signed-off-by: Sabrina Dubroca <sd@queasysnail.net>
Link: https://patch.msgid.link/8396631478f70454b44afb98352237d33f48d34d.1760432043.git.sd@queasysnail.net

Signed-off-by: Jakub Kicinski <kuba@kernel.org>

parent b8a6ff84

net/tls/tls_sw.c

+13 −0

Original line number	Diff line number	Diff line
		@@ -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;