[PATCH 6.6 049/105] tls: dont rely on tx_work during send()

Greg Kroah-Hartman
2025-10-21T19:54:53Z

From: Sabrina Dubroca <sd@queasysnail.net>

[ Upstream commit 7f846c65ca11e63d2409868ff039081f80e42ae4 ]

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 <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>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
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 6ea557ebab171..410e39e4b79fd 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