lmc: Read outside array bounds

If dev_alloc_skb() fails on the first iteration of the allocation loop,
then we end up writing before the start of the array.
Signed-off-by: NRoel Kluin <roel.kluin@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

drivers/net/wan/lmc/lmc_main.c

@@ -1897,11 +1897,12 @@ static void lmc_softreset (lmc_softc_t * const sc) /*fold00*/
     /*
      * Sets end of ring
      */
-    sc->lmc_rxring[i - 1].length |= 0x02000000; /* Set end of buffers flag */
-    sc->lmc_rxring[i - 1].buffer2 = virt_to_bus (&sc->lmc_rxring[0]); /* Point back to the start */
+    if (i != 0) {
+        sc->lmc_rxring[i - 1].length |= 0x02000000; /* Set end of buffers flag */
+        sc->lmc_rxring[i - 1].buffer2 = virt_to_bus(&sc->lmc_rxring[0]); /* Point back to the start */
+    }
     LMC_CSR_WRITE (sc, csr_rxlist, virt_to_bus (sc->lmc_rxring)); /* write base address */
 
-
     /* Initialize the transmit rings and buffers */
     for (i = 0; i < LMC_TXDESCS; i++)
     {