hw/misc/arm_sysctl: Fix bad boundary check on mb clock accesses

Fix incorrect use of sizeof() rather than ARRAY_SIZE() to guard
accesses into the mb_clock[] array, which was allowing a malicious
guest to overwrite the end of the array.
Signed-off-by: NPeter Maydell <peter.maydell@linaro.org>
Reviewed-by: NPaolo Bonzini <pbonzini@redhat.com>
Reviewed-by: NAndreas Färber <afaerber@suse.de>
Message-id: 1392647854-8067-2-git-send-email-peter.maydell@linaro.org
Cc: qemu-stable@nongnu.org

hw/misc/arm_sysctl.c

@@ -276,7 +276,7 @@ static bool vexpress_cfgctrl_read(arm_sysctl_state *s, unsigned int dcc,
         }
         break;
     case SYS_CFG_OSC:
-        if (site == SYS_CFG_SITE_MB && device < sizeof(s->mb_clock)) {
+        if (site == SYS_CFG_SITE_MB && device < ARRAY_SIZE(s->mb_clock)) {
             /* motherboard clock */
             *val = s->mb_clock[device];
             return true;
@@ -324,7 +324,7 @@ static bool vexpress_cfgctrl_write(arm_sysctl_state *s, unsigned int dcc,
 
     switch (function) {
     case SYS_CFG_OSC:
-        if (site == SYS_CFG_SITE_MB && device < sizeof(s->mb_clock)) {
+        if (site == SYS_CFG_SITE_MB && device < ARRAY_SIZE(s->mb_clock)) {
             /* motherboard clock */
             s->mb_clock[device] = val;
             return true;