highbank: validate register offset before access

An 'offset' parameter sent to highbank register r/w functions
could be greater than number(NUM_REGS=0x200) of hb registers,
leading to an OOB access issue. Add check to avoid it.

Reported-by: Moguofang (Dennis mo) <moguofang@huawei.com>
Signed-off-by: Prasad J Pandit <pjp@fedoraproject.org>
Message-id: 20171113062658.9697-1-ppandit@redhat.com
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

diff --git a/hw/arm/highbank.c b/hw/arm/highbank.c
index 354c6b25a8a2e7993c259912ad5dab30d59206ad..287392bbdc975bc7eca34f09d82b3f6237564624 100644 (file)
--- a/hw/arm/highbank.c
+++ b/hw/arm/highbank.c
@@ -34,6 +34,7 @@
 #include "hw/ide/ahci.h"
 #include "hw/cpu/a9mpcore.h"
 #include "hw/cpu/a15mpcore.h"
+#include "qemu/log.h"
 
 #define SMP_BOOT_ADDR           0x100
 #define SMP_BOOT_REG            0x40
@@ -117,14 +118,26 @@ static void hb_regs_write(void *opaque, hwaddr offset,
         }
     }
 
-    regs[offset/4] = value;
+    if (offset / 4 >= NUM_REGS) {
+        qemu_log_mask(LOG_GUEST_ERROR,
+                  "highbank: bad write offset 0x%" HWADDR_PRIx "\n", offset);
+        return;
+    }
+    regs[offset / 4] = value;
 }
 
 static uint64_t hb_regs_read(void *opaque, hwaddr offset,
                              unsigned size)
 {
+    uint32_t value;
     uint32_t *regs = opaque;
-    uint32_t value = regs[offset/4];
+
+    if (offset / 4 >= NUM_REGS) {
+        qemu_log_mask(LOG_GUEST_ERROR,
+                  "highbank: bad read offset 0x%" HWADDR_PRIx "\n", offset);
+        return 0;
+    }
+    value = regs[offset / 4];
 
     if ((offset == 0x100) || (offset == 0x108) || (offset == 0x10C)) {
         value |= 0x30000000;