net: systemport: do not crash freeing an unitialized TX ring

Callers of bcm_sysport_init_tx_ring() can currently fail, and will
always call bcm_sysport_fini_tx_ring() in a loop ending at the number of
TX queues (32) without checking if the TX ring was successfully
initialized or not.

Update bcm_sysport_fini_tx_ring() to return early and avoid a crash
de-referencing ring->cbs if the TX ring was not initialized, since
ring->cbs is the last part of the initialization done by
bcm_sysport_init_tx_ring() that could fail.

Fixes: 80105befdb4b ("net: systemport: add Broadcom SYSTEMPORT Ethernet MAC driver")
Reported-by: Maxime Bizon <mbizon@freebox.fr>
Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/drivers/net/ethernet/broadcom/bcmsysport.c b/drivers/net/ethernet/broadcom/bcmsysport.c
index c81bf74..531bb7c 100644 (file)
--- a/drivers/net/ethernet/broadcom/bcmsysport.c
+++ b/drivers/net/ethernet/broadcom/bcmsysport.c
@@ -1175,6 +1175,13 @@ static void bcm_sysport_fini_tx_ring(struct bcm_sysport_priv *priv,
        if (!(reg & TDMA_DISABLED))
                netdev_warn(priv->netdev, "TDMA not stopped!\n");
 
+       /* ring->cbs is the last part in bcm_sysport_init_tx_ring which could
+        * fail, so by checking this pointer we know whether the TX ring was
+        * fully initialized or not.
+        */
+       if (!ring->cbs)
+               return;
+
        napi_disable(&ring->napi);
        netif_napi_del(&ring->napi);