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    Subject[PATCH 4.19 09/32] net/tls: Protect from calling tls_dev_del for TLS RX twice
    Date
    From: Maxim Mikityanskiy <maximmi@mellanox.com>

    [ 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@mellanox.com>
    Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>
    Link: https://lore.kernel.org/r/20201125221810.69870-1-saeedm@nvidia.com
    Signed-off-by: Jakub Kicinski <kuba@kernel.org>
    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
    ---
    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);

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