[IA64] mca_drv: Add minstate validation

MCA driver can cause panic if kernel gets a state info with no minstate.
This patch adds minstate validation before handling it.

Signed-off-by: Hidetoshi Seto <[e-mail]>
Signed-off-by: Tony Luck <[e-mail]>

arch/ia64/kernel/mca_drv.c

···
 	 *    the process not have any locks of kernel.
 	 */
 
+	/* Is minstate valid? */
+	if (!peidx_bottom(peidx) || !(peidx_bottom(peidx)->valid.minstate))
+		return 0;
 	psr1 =(struct ia64_psr *)&(peidx_minstate_area(peidx)->pmsa_ipsr);
 
 	/*