[PATCH 6.18 426/752] tls: Fix race condition in tls_sw_cancel_work_tx()

Sasha Levin
2026-02-28T17:54:05Z

From: Hyunwoo Kim <imv4bel@gmail.com>

[ Upstream commit 7bb09315f93dce6acc54bf59e5a95ba7365c2be4 ]

This issue was discovered during a code audit.

After cancel_delayed_work_sync() is called from tls_sk_proto_close(),
tx_work_handler() can still be scheduled from paths such as the
Delayed ACK handler or ksoftirqd.
As a result, the tx_work_handler() worker may dereference a freed
TLS object.

The following is a simple race scenario:

cpu0 cpu1

tls_sk_proto_close()
tls_sw_cancel_work_tx()
tls_write_space()
tls_sw_write_space()
if (!test_and_set_bit(BIT_TX_SCHEDULED, &tx_ctx->tx_bitmask))
set_bit(BIT_TX_SCHEDULED, &ctx->tx_bitmask);
cancel_delayed_work_sync(&ctx->tx_work.work);
schedule_delayed_work(&tx_ctx->tx_work.work, 0);

To prevent this race condition, cancel_delayed_work_sync() is
replaced with disable_delayed_work_sync().

Fixes: f87e62d45e51 ("net/tls: remove close callback sock unlock/lock around TX work flush")
Signed-off-by: Hyunwoo Kim <imv4bel@gmail.com>
Reviewed-by: Simon Horman <horms@kernel.org>
Reviewed-by: Sabrina Dubroca <sd@queasysnail.net>
Link: https://patch.msgid.link/aZgsFO6nfylfvLE7@v4bel
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
net/tls/tls_sw.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/tls/tls_sw.c b/net/tls/tls_sw.c
index d171353699800..c6a708ee21dc8 100644
--- a/net/tls/tls_sw.c
+++ b/net/tls/tls_sw.c
@@ -2533,7 +2533,7 @@ void tls_sw_cancel_work_tx(struct tls_context *tls_ctx)

set_bit(BIT_TX_CLOSING, &ctx->tx_bitmask);
set_bit(BIT_TX_SCHEDULED, &ctx->tx_bitmask);
- cancel_delayed_work_sync(&ctx->tx_work.work);
+ disable_delayed_work_sync(&ctx->tx_work.work);
}

void tls_sw_release_resources_tx(struct sock *sk)
--
2.51.0