In the Linux kernel, the following vulnerability has been resolved:

tls: Fix race condition in tls_sw_cancel_work_tx()

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().