ibmtr: possible Read buffer overflow?

Prevent read outside array bounds.

Signed-off-by: Roel Kluin <[e-mail]>
Signed-off-by: David S. Miller <[e-mail]>

drivers/net/tokenring/ibmtr.c

···
                 } else {
 			char **prphase = printphase;
 			char **prerror = printerror;
+			int pnr = err / 16 - 1;
+			int enr = err % 16 - 1;
 			DPRINTK("TR Adapter misc open failure, error code = ");
-			printk("0x%x, Phase: %s, Error: %s\n",
-				err, prphase[err/16 -1], prerror[err%16 -1]);
+			if (pnr < 0 || pnr >= ARRAY_SIZE(printphase) ||
+					enr < 0 ||
+					enr >= ARRAY_SIZE(printerror))
+				printk("0x%x, invalid Phase/Error.", err);
+			else
+				printk("0x%x, Phase: %s, Error: %s\n", err,
+						prphase[pnr], prerror[enr]);
 			printk(" retrying after %ds delay...\n",
 					TR_RETRY_INTERVAL/HZ);
                 }