[PATCH 4.19 09/32] net/tls: Protect from calling tls_dev_del for TLS RX twice

[Greg Kroah-Hartman]

From: Maxim Mikityanskiy <maximmi@xxxxxxxxxxxx>

[ Upstream commit 025cc2fb6a4e84e9a0552c0017dcd1c24b7ac7da ]

tls_device_offload_cleanup_rx doesn't clear tls_ctx->netdev after
calling tls_dev_del if TLX TX offload is also enabled. Clearing
tls_ctx->netdev gets postponed until tls_device_gc_task. It leaves a
time frame when tls_device_down may get called and call tls_dev_del for
RX one extra time, confusing the driver, which may lead to a crash.

This patch corrects this racy behavior by adding a flag to prevent
tls_device_down from calling tls_dev_del the second time.

Fixes: e8f69799810c ("net/tls: Add generic NIC offload infrastructure")
Signed-off-by: Maxim Mikityanskiy <maximmi@xxxxxxxxxxxx>
Signed-off-by: Saeed Mahameed <saeedm@xxxxxxxxxx>
Link: https://lore.kernel.org/r/20201125221810.69870-1-saeedm@xxxxxxxxxx
Signed-off-by: Jakub Kicinski <kuba@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
 include/net/tls.h    |    6 ++++++
 net/tls/tls_device.c |    5 ++++-
 2 files changed, 10 insertions(+), 1 deletion(-)

--- a/include/net/tls.h
+++ b/include/net/tls.h
@@ -163,6 +163,12 @@ enum {
 
 enum tls_context_flags {
 	TLS_RX_SYNC_RUNNING = 0,
+	/* tls_dev_del was called for the RX side, device state was released,
+	 * but tls_ctx->netdev might still be kept, because TX-side driver
+	 * resources might not be released yet. Used to prevent the second
+	 * tls_dev_del call in tls_device_down if it happens simultaneously.
+	 */
+	TLS_RX_DEV_CLOSED = 2,
 };
 
 struct cipher_context {
--- a/net/tls/tls_device.c
+++ b/net/tls/tls_device.c
@@ -955,6 +955,8 @@ void tls_device_offload_cleanup_rx(struc
 	if (tls_ctx->tx_conf != TLS_HW) {
 		dev_put(netdev);
 		tls_ctx->netdev = NULL;
+	} else {
+		set_bit(TLS_RX_DEV_CLOSED, &tls_ctx->flags);
 	}
 out:
 	up_read(&device_offload_lock);
@@ -984,7 +986,8 @@ static int tls_device_down(struct net_de
 		if (ctx->tx_conf == TLS_HW)
 			netdev->tlsdev_ops->tls_dev_del(netdev, ctx,
 							TLS_OFFLOAD_CTX_DIR_TX);
-		if (ctx->rx_conf == TLS_HW)
+		if (ctx->rx_conf == TLS_HW &&
+		    !test_bit(TLS_RX_DEV_CLOSED, &ctx->flags))
 			netdev->tlsdev_ops->tls_dev_del(netdev, ctx,
 							TLS_OFFLOAD_CTX_DIR_RX);
 		WRITE_ONCE(ctx->netdev, NULL);