tls: fix race between tx work scheduling and socket close

Similarly to previous commit, the submitting thread (recvmsg/sendmsg)
may exit as soon as the async crypto handler calls complete().
Reorder scheduling the work before calling complete().
This seems more logical in the first place, as it's
the inverse order of what the submitting thread will do.

Reported-by: valis <sec@valis.email>
Fixes: a42055e ("net/tls: Add support for async encryption of records for performance")
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Reviewed-by: Simon Horman <horms@kernel.org>
Reviewed-by: Sabrina Dubroca <sd@queasysnail.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

Author: kuba-moo

net/tls/tls_sw.c

@@ -447,7 +447,6 @@ static void tls_encrypt_done(void *data, int err)
 	struct tls_rec *rec = data;
 	struct scatterlist *sge;
 	struct sk_msg *msg_en;
-	bool ready = false;
 	struct sock *sk;
 
 	msg_en = &rec->msg_encrypted;
@@ -483,19 +482,16 @@ static void tls_encrypt_done(void *data, int err)
 		/* If received record is at head of tx_list, schedule tx */
 		first_rec = list_first_entry(&ctx->tx_list,
 					     struct tls_rec, list);
-		if (rec == first_rec)
-			ready = true;
+		if (rec == first_rec) {
+			/* Schedule the transmission */
+			if (!test_and_set_bit(BIT_TX_SCHEDULED,
+					      &ctx->tx_bitmask))
+				schedule_delayed_work(&ctx->tx_work.work, 1);
+		}
 	}
 
 	if (atomic_dec_and_test(&ctx->encrypt_pending))
 		complete(&ctx->async_wait.completion);
-
-	if (!ready)
-		return;
-
-	/* Schedule the transmission */
-	if (!test_and_set_bit(BIT_TX_SCHEDULED, &ctx->tx_bitmask))
-		schedule_delayed_work(&ctx->tx_work.work, 1);
 }
 
 static int tls_encrypt_async_wait(struct tls_sw_context_tx *ctx)